http://www.cawses.org/wiki/index.php?title=Special:Contributions&feed=atom&target=MarshCAWSES - User contributions [en]2024-03-29T07:43:34ZFrom CAWSESMediaWiki 1.15.5http://www.cawses.org/wiki/index.php/Project_1.3_Changes_in_MLTI_dynamics_and_compositionProject 1.3 Changes in MLTI dynamics and composition2012-10-16T19:59:51Z<p>Marsh: Undo revision 767 by Marsh (Talk)</p>
<hr />
<div>* Project leaders: G. Beig (India), C. Jacobi (Germany) <br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
<br />
== Introduction ==<br />
<br />
Only, recently, a consistent picture of middle and upper atmosphere trends has been established (Lastovicka, 2009). However, the MLTI region responds to changes in solar/extraterrestrial forcing, changes of atmospheric composition, and to changes of the lower atmosphere dynamics. To estimate the relative roles of each of these forcing mechanisms, detailed knowledge on MLTI changes and trends not only in temperature, but also in dynamics and composition is required. The focus of the project is thus to analyze and quantify changes in wind and composition, and investigate the sources of MLTI changes in connection with forcing from above and especially below. <br />
<br />
This raises the following questions: How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT? Are there related trends observed in the MLTI?<br />
<br />
== Studies of Dynamics and Composition ==<br />
<br />
'''Dynamics''' <br />
<br />
Studies of the long-term variability of the mesosphere and lower thermosphere dynamics have been carried out for more than 40 years now, essentially by radar measurements, but also by OH emission (Höppner and Bittner, 2007). Already Greisiger et al. (1987) concluded that there is a possible quasi-decadal internal atmospheric variability of the prevailing circulation instead of a direct solar control. Additionally wind oscillations with periods from 2 to 5 years have frequently been reported (for instance, Namboothiri et al., 1994; Portnyagin, 1986). The year-to-year wind variability in the MLT region is observed on the background of secular changes in the circulation (for instance, Bremer, 1997; Jacobi et al., 2005; Merzlyakov et al., 2009). These studies investigated different time intervals of wind measurements, and they sometimes revealed opposite trends in the prevailing wind and in tidal parameters. <br />
<br />
A mechanism linking the summer polar MLTI to the winter lower atmosphere has been proposed (Koernich and Becker 2010 ) to explain observations and modeling studies (e.g. Karlsson et al. 2009). This mechanism relates a modulation of the gravity-wave flux in the winter hemisphere to changes in the strength of the meridional circulation responsible for forcing the summer mesosphere away from radiative equilibrium. Further comparisons with observations will test this mechanism and provide insight into the effect changes in the lower atmosphere will have on the MLTI.<br />
<br />
'''Composition'''<br />
<br />
Long-term trends of lower ionospheric parameters like foE, are owing to the decrease of ionospheric layers through middle atmosphere cooling, changes in transport of ionized species, and changes of ionization through temperature dependence of reaction rates. Trend analyses are essentially based on ionosonde data. More detailed knowledge on ion composition trends is required.<br />
<br />
== Methods and Analysis ==<br />
<br />
[[File:Collm_winter_wind.jpg|400px|thumb|right|Fig. 1: Winter zonal prevailing winds over Collm (52N, 15E), and results of a piecewise linear trend analysis indicating possible structural changes of MLTI trends. ]]<br />
<br />
It should be noted that usually a simple linear regression model has been used for trend assessments. However, recent analysis have indicated that long-term trends show structural changes - often called breakpoints -, which partly have been analyzed using piecewise linear fitting (Merzlyakov et al., 2009; Jacobi et al., 2009). The results reveal changes of trends (see an example in Figure 1) which, through their coincidence with breakpoints in lower atmospheric dynamics or composition, frequently can be attributed to tropospheric or stratospheric changes (e.g., Offermann et al., 2006). The change in mesopause region seasonal variations observed since 2001 by Reisin and Scheer ( 2009) may be a related phenomenon. In particular, MLTI trend change breakpoints have been identified in connection with tropospheric temperature changes in the late 1970s, changes of oscillation patterns like NAO in the 1990s, global ozone tendencies. Use of advanced techniques for trend estimation thus allows drawing more conclusions on the origin of MLTI trends and changes, and on coupling processes throughout the atmosphere.<br />
<br />
A model to analyse piecewise trends has been developed (Liu et al., 2010). The source code is available on request to jacobi (at) uni-leipzig.de.<br />
<br />
Long-term trend analyses of various parameters in the past have sometimes revealed different or even contradicting results for geographically relatively close sites and similar longitudes. This indicates the presence of stationary planetary waves and their changes. Satellite data analyses will provide more insight into planetary waves in the MLTI (Pancheva et al., 2010), and, together with local time series, explain differences in long-term time series analysis results.<br />
<br />
== Questions and Tasks ==<br />
<br />
=== Questions ===<br />
<br />
#Analysis of variability of MLTI parameters at time scales of years to decades. Is it possible to derive a consistent picture of MLTI trends and changes of different parameters?<br />
#Which is the possible coupling of MLTI changes, breakpoints in trends, or shifts with lower atmosphere changes?<br />
#Are there regional features connected with planetary waves, which may lead to different trends and signatures of lower atmospheric dynamics in different MLTI time series. Satellite data analysis will be helpful in this context.<br />
#Is there an influence of regional gravity wave signatures on MLTI trends?<br />
#Results from existing networks like the NDMC should be used.<br />
<br />
<br />
=== Activities ===<br />
<br />
''' TREND2010 workshop '''<br />
<br />
Several papers related to the project have been presented at the "6th IAGA/ICMA/CAWSES workshop on Long-Term Changes and Trends in the Atmosphere" [http://www.hao.ucar.edu/TREND2010/index.php], which was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June 15-18, 2010.<br />
<br />
<br />
[[File:NDMC_stations.jpg|300px|thumb|right|NDMC: currently 49 NDMC airglow stations. ]]<br />
<br />
''' NDMC '''<br />
<br />
Recently, the Network for the Detection of Mesopause Change <br />
(NDMC,http://wdc.dlr.de/ndmc) has been established as a global <br />
program with the mission to promote international cooperation <br />
among research groups investigating the mesopause region (80-100 km) with the goal of early<br />
identification of changing climate signals. This program involves the<br />
coordinated study of atmospheric variability at all time scales, the<br />
exchange of existing know-how, and the coordinated development of improved<br />
observation, analysis techniques and modeling. The initial emphasis is on<br />
mesopause region airglow techniques utilizing the existing ground-based<br />
and satellite measurement capabilities. Participation or association of<br />
researchers using other techniques in the same altitude region will be<br />
actively developed. NDMC is concerned with coupling processes and will<br />
interface with related activities throughout the atmosphere. It is<br />
affiliated with the Global Atmosphere Watch program of the World<br />
Meteorological Organization and with the Network for the Detection of<br />
Atmospheric Composition Change.<br />
<br />
<br />
<br />
''' TREND2012 workshop '''<br />
<br />
Several papers related to the project have been presented at the "7th IAGA/ICMA/CAWSES workshop on Long-Term Changes and Trends in the Atmosphere" [http://www1.herrera.unt.edu.ar/faceyt/trends2012/], which was held at the University of CEMA, UCEMA, Buenos Aires September 11-14, 2012.<br />
<br />
== Projects ==<br />
<br />
<br />
[[File:Obninsk-Collm.jpg|400px|thumb|right|Fig. 2: Obninsk (55°N, 37°E) and Collm (52°N, 15°E) winter MLT zonal prevailing winds as well as their differences (blue line). The zonal wind differences at this relatively short distance is correlated with stationary planetary waves (SPW) in the stratosphere (pink line). ]]<br />
<br />
=== Non-zonal stuctures seen in trends and interannual variability ===<br />
<br />
<br />
Recent analyses have shown that long-term trends and interanual variability of MLTI parameter measurements distributed in longitude may be different, <br />
and tendencies are partly contradicting. This is the case also at relatively short zonal distances of 1000-2000 km and indicates quasi-stationary structures. Part of these non-zonal structures are connected with <br />
stationary planetary waves (SPW), as shown in Fig.1.<br />
The project aims at determining the spatial scales of these structures, and their origin. Work within the project includes:<br />
#Analysis of trends and variability from MLT radar winds at different stations, and correlation with stratospheric SPW,<br />
#Use of NDMC to analyse MLT temperature structures,<br />
#Analysis of in situ SPW from satellite measurements,<br />
#Gravity wave analysis, <br />
#Numerical modelling of wave propagation and effects on the MLTI,<br />
#Investigation of lower ionospheric non-zonal structures that may affect MLT dynamics.<br />
<br />
<br />
<br />
== References ==<br />
<br />
Greisiger,K.M.,Schminder,R.,Kürschner,D.,1987.Long-period variations of wind parameters in the mesopause region and the solar cycle dependence. Journal of Atmospheric and Terrestrial Physics 49, 281–285.<br />
<br />
Höppner, K., Bittner, M., 2007: Evidence for solar signals in the mesopause temperature variability?, Journal of Atmospheric and Solar-Terrestrial Physics 69, 431-448.<br />
<br />
Jacobi, Ch., Portnyagin, Yu.I., Merzlyakov, E.G., Solovjova, T.V., Makarov, N.A., Kürschner, D., 2005. A long-term comparison of mesopause region wind measurements over Eastern and Central Europe. Journal of Atmospheric and Solar-Terrestrial Physics 67, 229–240.<br />
<br />
Jacobi, Ch., P. Hoffmann, R.Q. Liu, P. Križan, J. Laštovička, E.G. Merzlyakov, T.V. Solovjova, and Yu.I. Portnyagin, 2009: Midlatitude mesopause region winds and waves and comparison with stratospheric variability. Journal of Atmospheric and Solar-Terrestrial Physics 71, 1540-1546. <br />
<br />
Lastovicka, J., 2009: Global pattern of trends in the upper atmosphere and ionosphere: Recent progress, Journal of Atmospheric and Solar-Terrestrial Physics, 71, 14-15.<br />
<br />
Karlsson, B, McLandress, M., and Shepherd, T. G. , 2009: Inter-hemispheric mesospheric coupling in a comprehensive middle atmosphere model, J. Atmos, Sol-Terr Phys., 71, 518-530.<br />
<br />
Koernich, H. and Becker, E., 2010: A simple model for the interhemispheric coupling of the middle atmosphere circulation, Adv. Spac. Res. , 45, 5, 661-668.<br />
<br />
Liu, R.Q., Ch. Jacobi, P. Hoffmann, G. Stober, and E. G. Merzlyakov, 2010: A piecewise linear model for detecting climatic trends and their structural changes with application to mesosphere/lower thermosphere winds over Collm, Germany. J. Geophys. Res., 115, D22105, doi:10.1029/2010JD014080.<br />
<br />
Merzlyakov, E.G., Ch. Jacobi, Yu.I. Portnyagin, and T.V. Solovjova, 2009: Structural changes in trend parameters of the MLT winds based on wind measurements at Obninsk (55°N, 37°E) and Collm (52°N, 15°E). Journal of Atmospheric and Solar-Terrestrial Physics 71, 1547-1557.<br />
<br />
Namboothiri, S.P., Meek, C.E., Manson, A.H., 1994. Variations of mean winds and solar tides in the mesosphere and lower thermosphere over time scales ranging from 6 months to 11 yr: Saskatoon, 52°N, 107°W. Journal of Atmospheric and Terrestrial Physics 56, 1313–1325.<br />
<br />
Offermann, D., Jarisch, M., Donner, M., Steinbrecht, W., Semenov, A.I., 2006. OH temperature re-analysis forced by recent variance increases. Journal of Atmospheric and Solar-Terrestrial Physics, 68, 1924–1933.<br />
<br />
Pancheva, D., Mukhtarov, P. , Andonov, B., Forbes, J.M., 2010: Global distribution and climatological features of the 5-6-day planetary waves seen in the SABER/TIMED temperatures (2002-2007), Journal of Atmospheric and Solar-Terrestrial Physics, 72, Pages 26-37.<br />
<br />
Portnyagin, Yu.I., 1986. The climatic wind regime in the lower thermosphere from meteor radar observations. Journal of Atmospheric and Terrestrial Physics 48, 1099–1109.<br />
<br />
Reisin, E.R., Scheer, J, 2009: Evidence of change after 2001 in the seasonal behaviour of the mesopause region from airglow data at El Leoncito, Advances in Space Research, 44, 401-412.</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.3_Changes_in_MLTI_dynamics_and_compositionProject 1.3 Changes in MLTI dynamics and composition2012-10-16T19:58:37Z<p>Marsh: /* Activities */</p>
<hr />
<div>* Project leaders: G. Beig (India), C. Jacobi (Germany) <br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
<br />
== Introduction ==<br />
<br />
Only, recently, a consistent picture of middle and upper atmosphere trends has been established (Lastovicka, 2009). However, the MLTI region responds to changes in solar/extraterrestrial forcing, changes of atmospheric composition, and to changes of the lower atmosphere dynamics. To estimate the relative roles of each of these forcing mechanisms, detailed knowledge on MLTI changes and trends not only in temperature, but also in dynamics and composition is required. The focus of the project is thus to analyze and quantify changes in wind and composition, and investigate the sources of MLTI changes in connection with forcing from above and especially below. <br />
<br />
This raises the following questions: How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT? Are there related trends observed in the MLTI?<br />
<br />
== Studies of Dynamics and Composition ==<br />
<br />
'''Dynamics''' <br />
<br />
Studies of the long-term variability of the mesosphere and lower thermosphere dynamics have been carried out for more than 40 years now, essentially by radar measurements, but also by OH emission (Höppner and Bittner, 2007). Already Greisiger et al. (1987) concluded that there is a possible quasi-decadal internal atmospheric variability of the prevailing circulation instead of a direct solar control. Additionally wind oscillations with periods from 2 to 5 years have frequently been reported (for instance, Namboothiri et al., 1994; Portnyagin, 1986). The year-to-year wind variability in the MLT region is observed on the background of secular changes in the circulation (for instance, Bremer, 1997; Jacobi et al., 2005; Merzlyakov et al., 2009). These studies investigated different time intervals of wind measurements, and they sometimes revealed opposite trends in the prevailing wind and in tidal parameters. <br />
<br />
A mechanism linking the summer polar MLTI to the winter lower atmosphere has been proposed (Koernich and Becker 2010 ) to explain observations and modeling studies (e.g. Karlsson et al. 2009). This mechanism relates a modulation of the gravity-wave flux in the winter hemisphere to changes in the strength of the meridional circulation responsible for forcing the summer mesosphere away from radiative equilibrium. Further comparisons with observations will test this mechanism and provide insight into the effect changes in the lower atmosphere will have on the MLTI.<br />
<br />
'''Composition'''<br />
<br />
Long-term trends of lower ionospheric parameters like foE, are owing to the decrease of ionospheric layers through middle atmosphere cooling, changes in transport of ionized species, and changes of ionization through temperature dependence of reaction rates. Trend analyses are essentially based on ionosonde data. More detailed knowledge on ion composition trends is required.<br />
<br />
== Methods and Analysis ==<br />
<br />
[[File:Collm_winter_wind.jpg|400px|thumb|right|Fig. 1: Winter zonal prevailing winds over Collm (52N, 15E), and results of a piecewise linear trend analysis indicating possible structural changes of MLTI trends. ]]<br />
<br />
It should be noted that usually a simple linear regression model has been used for trend assessments. However, recent analysis have indicated that long-term trends show structural changes - often called breakpoints -, which partly have been analyzed using piecewise linear fitting (Merzlyakov et al., 2009; Jacobi et al., 2009). The results reveal changes of trends (see an example in Figure 1) which, through their coincidence with breakpoints in lower atmospheric dynamics or composition, frequently can be attributed to tropospheric or stratospheric changes (e.g., Offermann et al., 2006). The change in mesopause region seasonal variations observed since 2001 by Reisin and Scheer ( 2009) may be a related phenomenon. In particular, MLTI trend change breakpoints have been identified in connection with tropospheric temperature changes in the late 1970s, changes of oscillation patterns like NAO in the 1990s, global ozone tendencies. Use of advanced techniques for trend estimation thus allows drawing more conclusions on the origin of MLTI trends and changes, and on coupling processes throughout the atmosphere.<br />
<br />
A model to analyse piecewise trends has been developed (Liu et al., 2010). The source code is available on request to jacobi (at) uni-leipzig.de.<br />
<br />
Long-term trend analyses of various parameters in the past have sometimes revealed different or even contradicting results for geographically relatively close sites and similar longitudes. This indicates the presence of stationary planetary waves and their changes. Satellite data analyses will provide more insight into planetary waves in the MLTI (Pancheva et al., 2010), and, together with local time series, explain differences in long-term time series analysis results.<br />
<br />
== Questions and Tasks ==<br />
<br />
=== Questions ===<br />
<br />
#Analysis of variability of MLTI parameters at time scales of years to decades. Is it possible to derive a consistent picture of MLTI trends and changes of different parameters?<br />
#Which is the possible coupling of MLTI changes, breakpoints in trends, or shifts with lower atmosphere changes?<br />
#Are there regional features connected with planetary waves, which may lead to different trends and signatures of lower atmospheric dynamics in different MLTI time series. Satellite data analysis will be helpful in this context.<br />
#Is there an influence of regional gravity wave signatures on MLTI trends?<br />
#Results from existing networks like the NDMC should be used.<br />
<br />
<br />
=== Activities ===<br />
<br />
''' TREND2012 workshop '''<br />
<br />
Oral presentations have already been uploaded to the Workshop website for open access). You can download the pdf version of each presentation from the “Scientific Program” at http://www1.herrera.unt.edu.ar/faceyt/trends2012/scientific-program/<br />
<br />
''' TREND2010 workshop '''<br />
<br />
Several papers related to the project have been presented at the "6th IAGA/ICMA/CAWSES workshop on Long-Term Changes and Trends in the Atmosphere" [http://www.hao.ucar.edu/TREND2010/index.php], which was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June 15-18, 2010.<br />
<br />
<br />
[[File:NDMC_stations.jpg|300px|thumb|right|NDMC: currently 49 NDMC airglow stations. ]]<br />
<br />
''' NDMC '''<br />
<br />
Recently, the Network for the Detection of Mesopause Change <br />
(NDMC,http://wdc.dlr.de/ndmc) has been established as a global <br />
program with the mission to promote international cooperation <br />
among research groups investigating the mesopause region (80-100 km) with the goal of early<br />
identification of changing climate signals. This program involves the<br />
coordinated study of atmospheric variability at all time scales, the<br />
exchange of existing know-how, and the coordinated development of improved<br />
observation, analysis techniques and modeling. The initial emphasis is on<br />
mesopause region airglow techniques utilizing the existing ground-based<br />
and satellite measurement capabilities. Participation or association of<br />
researchers using other techniques in the same altitude region will be<br />
actively developed. NDMC is concerned with coupling processes and will<br />
interface with related activities throughout the atmosphere. It is<br />
affiliated with the Global Atmosphere Watch program of the World<br />
Meteorological Organization and with the Network for the Detection of<br />
Atmospheric Composition Change.<br />
<br />
<br />
<br />
''' TREND2012 workshop '''<br />
<br />
Several papers related to the project have been presented at the "7th IAGA/ICMA/CAWSES workshop on Long-Term Changes and Trends in the Atmosphere" [http://www1.herrera.unt.edu.ar/faceyt/trends2012/], which was held at the University of CEMA, UCEMA, Buenos Aires September 11-14, 2012.<br />
<br />
== Projects ==<br />
<br />
<br />
[[File:Obninsk-Collm.jpg|400px|thumb|right|Fig. 2: Obninsk (55°N, 37°E) and Collm (52°N, 15°E) winter MLT zonal prevailing winds as well as their differences (blue line). The zonal wind differences at this relatively short distance is correlated with stationary planetary waves (SPW) in the stratosphere (pink line). ]]<br />
<br />
=== Non-zonal stuctures seen in trends and interannual variability ===<br />
<br />
<br />
Recent analyses have shown that long-term trends and interanual variability of MLTI parameter measurements distributed in longitude may be different, <br />
and tendencies are partly contradicting. This is the case also at relatively short zonal distances of 1000-2000 km and indicates quasi-stationary structures. Part of these non-zonal structures are connected with <br />
stationary planetary waves (SPW), as shown in Fig.1.<br />
The project aims at determining the spatial scales of these structures, and their origin. Work within the project includes:<br />
#Analysis of trends and variability from MLT radar winds at different stations, and correlation with stratospheric SPW,<br />
#Use of NDMC to analyse MLT temperature structures,<br />
#Analysis of in situ SPW from satellite measurements,<br />
#Gravity wave analysis, <br />
#Numerical modelling of wave propagation and effects on the MLTI,<br />
#Investigation of lower ionospheric non-zonal structures that may affect MLT dynamics.<br />
<br />
<br />
<br />
== References ==<br />
<br />
Greisiger,K.M.,Schminder,R.,Kürschner,D.,1987.Long-period variations of wind parameters in the mesopause region and the solar cycle dependence. Journal of Atmospheric and Terrestrial Physics 49, 281–285.<br />
<br />
Höppner, K., Bittner, M., 2007: Evidence for solar signals in the mesopause temperature variability?, Journal of Atmospheric and Solar-Terrestrial Physics 69, 431-448.<br />
<br />
Jacobi, Ch., Portnyagin, Yu.I., Merzlyakov, E.G., Solovjova, T.V., Makarov, N.A., Kürschner, D., 2005. A long-term comparison of mesopause region wind measurements over Eastern and Central Europe. Journal of Atmospheric and Solar-Terrestrial Physics 67, 229–240.<br />
<br />
Jacobi, Ch., P. Hoffmann, R.Q. Liu, P. Križan, J. Laštovička, E.G. Merzlyakov, T.V. Solovjova, and Yu.I. Portnyagin, 2009: Midlatitude mesopause region winds and waves and comparison with stratospheric variability. Journal of Atmospheric and Solar-Terrestrial Physics 71, 1540-1546. <br />
<br />
Lastovicka, J., 2009: Global pattern of trends in the upper atmosphere and ionosphere: Recent progress, Journal of Atmospheric and Solar-Terrestrial Physics, 71, 14-15.<br />
<br />
Karlsson, B, McLandress, M., and Shepherd, T. G. , 2009: Inter-hemispheric mesospheric coupling in a comprehensive middle atmosphere model, J. Atmos, Sol-Terr Phys., 71, 518-530.<br />
<br />
Koernich, H. and Becker, E., 2010: A simple model for the interhemispheric coupling of the middle atmosphere circulation, Adv. Spac. Res. , 45, 5, 661-668.<br />
<br />
Liu, R.Q., Ch. Jacobi, P. Hoffmann, G. Stober, and E. G. Merzlyakov, 2010: A piecewise linear model for detecting climatic trends and their structural changes with application to mesosphere/lower thermosphere winds over Collm, Germany. J. Geophys. Res., 115, D22105, doi:10.1029/2010JD014080.<br />
<br />
Merzlyakov, E.G., Ch. Jacobi, Yu.I. Portnyagin, and T.V. Solovjova, 2009: Structural changes in trend parameters of the MLT winds based on wind measurements at Obninsk (55°N, 37°E) and Collm (52°N, 15°E). Journal of Atmospheric and Solar-Terrestrial Physics 71, 1547-1557.<br />
<br />
Namboothiri, S.P., Meek, C.E., Manson, A.H., 1994. Variations of mean winds and solar tides in the mesosphere and lower thermosphere over time scales ranging from 6 months to 11 yr: Saskatoon, 52°N, 107°W. Journal of Atmospheric and Terrestrial Physics 56, 1313–1325.<br />
<br />
Offermann, D., Jarisch, M., Donner, M., Steinbrecht, W., Semenov, A.I., 2006. OH temperature re-analysis forced by recent variance increases. Journal of Atmospheric and Solar-Terrestrial Physics, 68, 1924–1933.<br />
<br />
Pancheva, D., Mukhtarov, P. , Andonov, B., Forbes, J.M., 2010: Global distribution and climatological features of the 5-6-day planetary waves seen in the SABER/TIMED temperatures (2002-2007), Journal of Atmospheric and Solar-Terrestrial Physics, 72, Pages 26-37.<br />
<br />
Portnyagin, Yu.I., 1986. The climatic wind regime in the lower thermosphere from meteor radar observations. Journal of Atmospheric and Terrestrial Physics 48, 1099–1109.<br />
<br />
Reisin, E.R., Scheer, J, 2009: Evidence of change after 2001 in the seasonal behaviour of the mesopause region from airglow data at El Leoncito, Advances in Space Research, 44, 401-412.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-10-16T19:55:23Z<p>Marsh: /* Past Meetings */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
* Gufran Beig (IN)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
== Past Meetings ==<br />
<br />
CEDAR 2012 Workshop session on Thermosphere and Ionosphere Climate 24-29 June 2012, Santa Fe, New Mexico, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere, which will be held in September 2012, in Buenos Aires, Argentina<br />
<br />
Second CAWSES-2 Task 2 Workshop: '''Modeling Polar Mesospheric Cloud Trends''', May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-10-16T19:54:11Z<p>Marsh: /* Upcoming Meetings */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
* Gufran Beig (IN)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
== Past Meetings ==<br />
<br />
Second CAWSES-2 Task 2 Workshop: '''Modeling Polar Mesospheric Cloud Trends''', May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-10-16T19:51:05Z<p>Marsh: /* How will Geospace Respond to a Changing Climate? */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
* Gufran Beig (IN)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
CEDAR 2012 Workshop session on ''' Thermosphere and Ionosphere Climate'''<br />
[http://cedarweb.hao.ucar.edu/wiki/index.php/2012_Workshop:Thermosphere_and_Ionosphere_Climate]<br />
24-29 June 2012, Santa Fe, New Mexico, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on''' Long-Term Changes and Trends in the Atmosphere''', which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
Second CAWSES-2 Task 2 Workshop: '''Modeling Polar Mesospheric Cloud Trends''', May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2012-05-13T19:41:48Z<p>Marsh: /* Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012 */</p>
<hr />
<div>* Project leaders: G.Thomas (USA), U.Berger (Germany)<br />
* Project members: S. Bailey (USA),G. Baumgarten(Germany),M. DeLand (USA), J. Fiedler (Germany),B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), F.-J. Lübken (Gemany), A. Merkel (USA), N. Pertsev (Russia), J. Russell III (USA), E. Shettle (USA)<br />
==Introduction==<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year time series of SBUV (Solar Backscatter Ultraviolet) satellite measurements (see Figure 1). SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable. It is important to understand the relative roles of these three factors (solar, inter-annual and long-term forcing) before a definitive long-term trend can be evaluated. Furthermore the problem of attribution, that is, the nature of the various forcings on ice formation is not yet understood. For example with respect to the long-term changes, is a lowered temperature due to higher carbon dioxide responsible for the observed increase in brightness and occurrence frequency of MC? Or are water vapor changes due to oxidation of methane responsible, since we know that lower atmospheric methane has more than doubled over the past 120 years, and methane oxidation leads to upper atmospheric water vapor. The failure to detect any changes in the altitude of MC since the first measurement made by Otto Jesse in the late nineteenth century has provided an important constraint, since water vapor changes and temperature changes affect cloud altitude in different ways. Fortunately, the state of the art in modeling has now reached a point where ice formation is coupled with general circulation models. In a recent study Berger and Lübken (2011) showed that in the summer period 1979 -1997 at mid-latitudes strong cooling of up to 3-4 K/decade occurs in the middle mesosphere, in the period 1961-1979 the middle atmosphere cooled significantly less, and for the period 1997-2009 they find a warming of ~1 K/decade. For the first time, modeled temperature trends confirm the extraordinarily large temperature trends observed at mid-latitudes during the period 1979-1997 derived from lidar measurements, satellite data, and phase height measurements. The differences in temperature trends in the mesosphere originate from the evolution of stratospheric ozone in the past 50 years, e.g. the observed reversal of both stratospheric and mesospheric temperature trends in the mid 1990s is caused by the recovery of <br />
stratospheric ozone (WMO report 2011). Therefore a new research question arises: does any trend in MC show a similar behavior? Relevant publications on this subject are reported in the references below:<br />
[[File:Vqn-fig2rev.png|thumb|Fig. 1 A comparison of the seasonal PMC frequency of occurrence measured by SBUV and the fit to a linear regression in time and solar activity (upper panel) by latitude band and (lower panel) for all latitude bands combined between 54°N and 82°N. The error bars are the confidence limits in the individual seasonal mean values based on counting statistics, which do not reflect other factors such as inter-annual variability in large scale dynamics (from Reference 5)]]<br />
<br />
==References==<br />
<br />
#Luebken, F.-J., U. Berger, and G. Baumgarten (2009), Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds, J. Geophys. Res., 114, D00I06, doi:10.1029/2009JD012377 <br />
#Merkel, A. W., Marsh, D. R., Gettelman, A., and Jensen, E. J.: On the relationship of polar mesospheric cloud ice water content, particle radius and mesospheric temperature and its use in multi-dimensional models, Atmos. Chem. Phys., 9, 8889-8901, 2009<br />
# Merkel, A. W., D. Marsh, G. E. Thomas, C. Bardeen, M. Deland, WACCM simulations of long-term changes in polar mesospheric clouds, Layered Phenomenon in Mesospheric Regions (LPMR) Conference, Stockholm, 2009<br />
#Marsh, D and A. W. Merkel, 30-year PMC variability modeled by WACCM, SA33B-08, Fall AGU Meeting, San Francisco, 2009<br />
#Shettle,E. P.,M. T. DeLand, G. E. Thomas, and J. J. Olivero (2009), Long term variations in the frequency of polar mesospheric clouds in the Northern Hemisphere from SBUV, Geophys. Res. Lett., 36, L02803, doi:10.1029/2008GL036048.<br />
#Thomas, G. E., D. Marsh and F.-J. Lübken, Mesospheric ice clouds as indicators of upper atmosphere climate change, EOS, Transactions, American Geophysical Union, 91, No. 20, 18 May 2010, p. 183.<br />
#Berger, U., and F.-J. Lübken (2011), Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., 38, L22804, doi: 10.1029/2011GL049528.<br />
#WMO (2011), Global ozone research and monitoring project-Report no. 52, Scientific assessment of ozone depletion: 2010, World Meteorological Organization<br />
<br />
<br />
=Workshops and Meetings=<br />
The first workshop under the auspices of this working group was held in Boulder, Colorado on December 10 & 11, 2010, entitled Modeling Trends in mesospheric clouds (Thomas et al, 2010).<br />
[[file:COSTEP_LOGO_240.gif|left|]]<br />
==[[Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012]]==<br />
<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, USA.<br />
<br />
The workshop was held in Boulder, CO USA on May 3-4, 2012. This is the 7th workshop sponsored by IAGA/ICMA/CAWSES and focusses on global change in the upper mesosphere, specifically decadal-scale trends in Polar Mesospheric Clouds, PMC (or Noctilucent Clouds, NLC, as they are traditionally called when observed from the ground at twilight).<br />
<br />
The issue of long-term changes in PMC was addressed in the first workshop in Boulder, Colorado, 10-11 December, 2009 (Thomas et al, 2010). A long suite of satellite measurements by the Solar Backscatter Ultraviolet Spectrometer (SBUV) dating back to 1979 shows a significant long-term trend in mesospheric cloud activity and brightness. Attribution of trends in these high-altitude ice clouds (~83 km) includes: (1) increasing carbon dioxide concentrations which tend to cool the upper mesosphere (the 80-90 km 'mesopause region'); (2) increasing water vapor due to growing concentrations of methane, in addition to changing efficiency of tropospheric water vapor entry through the tropopause; (3) shrinking of the upper atmosphere arising largely from decreased ozone levels and subsequent stratospheric cooling; (4) increased concentrations of water vapor due to the rise in space traffic over the last 30 years. Other possible causes are long-term changes in winds and wind filtering of gravity waves which dominate the dynamics of the high-latitude summertime mesopause region. An even larger (cyclic) trend is superimposed on the long-term record, believed to be a result of the solar cycle, but not well understood.<br />
<br />
General circulation models coupled with ice formation are now capable of simulating the SBUV trends to a remarkable degree, as discussed in the first workshop. However, new modeling results have brought out the importance of ozone trends, which affect the heat balance of the entire upper atmosphere. The LIMA/ICE model predicts a 'break-point' in the time series of PMC trends, due to the turn-around of the ozone trend in the mid-1990's. A wealth of new data from several satellite missions (AIM, ODIN, TIMED) are available. The Aeronomy of Ice in the Mesosphere (AIM) directly addresses the processes which control ice cloud evolution. In addition, more information is now available on diurnal variations in ice water content, which in principle affects the analysis of trends made from satellites in sun-synchronous orbits with slowly-varying local time coverage. These and other advances in modeling, data availability and trend analysis are motivations for a coming together of both modelers and data analysts to assess the current state of knowledge. A goal of the workshop would be to make recommendations for future work to resolve many of the outstanding issues.<br />
<br />
The PMC Trend Workshop was held at the Laboratory for Atmospheric Physics at the Space Science Building, the newest LASP location at the University Research Campus Park, University of Colorado, Boulder, Co, USA on May 3 and 4, 2012. <br />
<br />
Gary Thomas (thomas@lasp.colorado.edu) and Uwe Berger (berger@iap-kborn.de), co-chairs of CAWSES-II, Task 2, Project 3<br />
<br />
===MEETING AGENDA===<br />
<br />
==AM Thursday, May 3== <br />
<br />
0830-0840: Gary Thomas, LASP<br />
Welcome & Summary of Workshop Objectives<br />
<br />
====[[Long-term Trends: PMC Observations]]====<br />
0840-0900<br />
John Olivero, Embry-Riddle University, USA, Some Historical Notes on Noctilucent Cloud Studies<br />
<br />
0900-0910 Q&A, and discussion<br />
<br />
0910-0930 Matthew DeLand, SSAI, USA,Current PMC Trends Derived from SBUV Measurements<br />
<br />
0930-0940 Q&A, and discussion<br />
<br />
0940-1000 Mark Zalcik, Coordinator, NLC Can Am Network, Canada,Two Decades of Noctilucent Cloud Monitoring in North America<br />
<br />
1000-1010 Q&A, and discussion<br />
<br />
1010-1025 P. Dalin, Swedish Institute of Space Physics, Sweden,On the long-term trends in noctilucent clouds as observed from the ground and on the trends in the OH summer temperature as measured in Moscow and Lithuania<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
1100-1120 Gerd Baumgarten, IUP, Germany,Decadal observations of particle sizes and water vapor content of NLC<br />
<br />
1120-1130 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Temperature & Water Vapor Observations]]====<br />
<br />
1130-1150 Alain Hauchecorne, Laboratoire ATmosphères, France, Temperature trends in the stratosphere and in the mesosphere as seen from Rayleigh lidar observations<br />
<br />
1150-1200 Q&A, and discussion<br />
<br />
1200-1220 Karen Rosenlof, NOAA, USA , A new satellite based zonally averaged time series of stratospheric water vapor<br />
<br />
1220-1230 Q&A, and discussion<br />
<br />
1230-1330 Lunch Break<br />
<br />
==PM Thursday, May 3==<br />
<br />
====[[ Long-term Trends: Temperature & Water Vapor Observations (cont.)]]====<br />
<br />
1330-1350 Gerald Nedoluha, NRL, USA , Long-Term Ground-based Microwave Measurements of Middle Atmospheric Water Vapor from NDACC sites<br />
<br />
1350-1400 Q&A, and discussion<br />
<br />
1400-1420 Michael Stevens, NRL, USA ,The impact of space shuttle main engine exhaust on PMCs and implications to trend studies<br />
<br />
1420-1430 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Modeling]]====<br />
<br />
1430-1450 Uwe Berger, IUP, Germany,Solar variability and trend effects in mesospheric ice layers<br />
<br />
1450-1500 Q&A, and discussion<br />
<br />
1500-1520 Aimee Merkel, LASP, USA,WACCM-PMC simulations of long-term trends of PMC<br />
<br />
1520-1530 Q&A, and discussion<br />
<br />
1530-1600 Coffee Break<br />
<br />
1600-1620 David Siskind, NRL, USA,The PMC region as an integrator of coupling processes: Implications for trend studies from AIM and other missions<br />
<br />
1620-1630 Q&A, and discussion<br />
<br />
1630-1650 Stan Solomon, NCAR, USA,Thermospheric Temperature Trends: Modeling and Observations<br />
<br />
1650-1700 Q&A and discussion<br />
<br />
1700-1720 Dan Marsh, NCAR, USA,Climate change in the mesosphere from 1850 to 2100 in CESM-WACCM<br />
<br />
1720-1730 Q&A, and discussion<br />
<br />
1730-1750 Kota Okamoto, The University of Tokyo, Japan, On the dynamical responses in the middle atmosphere to ozone recovery and CO2 increase<br />
<br />
1750-1800 Q&A, and discussion<br />
<br />
1800 Adjourn<br />
<br />
1900-2100 Group Dinner (TBD)<br />
<br />
==AM Friday, Friday, May 4==<br />
<br />
====[[Inter-annual, hemispheric and seasonal variability: Observations]]====<br />
<br />
0830-0850 James Russell III, Hampton Univ, USA, AIM science results and their significance for PMC long-term change studies<br />
<br />
0850-0900 Q&A, and discussion <br />
<br />
0900-0920 Cora Randall, LASP, USA, AIM/CIPS Observations of PMC Variability<br />
<br />
0920-0930 Q&A, and discussion<br />
<br />
0930-0945 Rachel Ward, Utah State University, USA, Comparison of Northern and Southern Hemisphere Mesospheric Gravity Waves using CIPS PMC Data<br />
<br />
0945-0950 Q&A, and discussion<br />
<br />
0950-1005 Susanne Benze, LASP, USA, On the onset of polar mesospheric cloud seasons<br />
<br />
1005-1010 Q&A, and discussion<br />
<br />
1010-1025 Hanli Liu, NCAR, USA ,Fast meridional transport in the lower thermosphere by planetary-scale waves<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
====[[Properties of PMC and their Environment: Observations]]====<br />
<br />
1100-1115 E.J. Llewellyn, University of Saskatchewan, Canada, Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb<br />
<br />
1115-1120 Q&A, and discussion<br />
<br />
1120-1135 Scott Robertson, U of Colorado, USA, Detection of Meteoric Dust in Mesosphere by the CHAMPS Rockets<br />
<br />
1135-1140 Q&A, and discussion<br />
<br />
1140-1200 Kristell Pérot, LATMOS Laboratoire ATmosphères, France, PMC Particle Size Retrieval from GOMOS / ENVISAT Observations<br />
<br />
1200 -1210 Q&A and discussion<br />
<br />
1210-1310 Lunch<br />
<br />
==PM Friday, Friday, May 4==<br />
<br />
====[[Properties of PMC and their Environment: Modeling]]====<br />
<br />
1310-1330 Charles Bardeen, NCAR, USA, Simulations of PMC during the AIM time period using WACCM/CARMA<br />
<br />
1330-1340 Q&A, and discussion<br />
<br />
1340-1400 Mark Hervig, GATS, Inc., Variability in PMCs and their environment from SOFIE observations, and potential implications for PMC trends<br />
<br />
1400-1410 Q&A, and discussion<br />
<br />
1410-1425 I. Azeem, Astraspace, USA, Simulations of Shuttle Main Engine Plume Effects on Lower Thermosphere Energetics and Chemistry<br />
<br />
1425-1430 Q&A, and discussion<br />
<br />
1430-1445 Coffee Break<br />
<br />
Panel and group discussion<br />
<br />
1445-1545 Panel discussion<br />
<br />
1545-1630 Concluding remarks & summary from the project co-chairs<br />
<br />
1630 Adjourn<br />
<br />
==Local Organizing Committee: Aimee.Merkel@lasp.colorado.edu,Dan Marsh (marsh@ucar.edu) and Charles Bardeen (bardeenc@ucar.edu)==<br />
<br />
===NOTE: The Particle Size Workshop,originally scheduled for May 2, has been postponed to a later date.===<br />
<br />
==SPECIAL JOURNAL ISSUE ON UPPER ATMOSPHERIC TRENDS NOW AVAILABLE. The joint JGR/Space, JGR/Atmospheres special section on upper atmospheric trends is now complete, and can be accessed at http://www.agu.org/journals/ja/special_sections.shtml?collectionCode=UATREND1&amp;journalCode=JA==<br />
<br />
='''Observing Facilities'''=<br />
<br />
<br />
== Aeronomy of Ice in the Mesosphere (AIM), a NASA satellite mission (2007-) ==<br />
[[File:AIMforWIKI.png|left|Fig. 2 Artist's conception of the AIM spacecraft in orbit, showing the line of sight of the SOFIE solar occultation experiment (courtesy, J. Russell III]][[File:CIPSfig1.png|right|]]AIM was launched from Vandenberg Air Force Base on April 25, 2007 becoming the first satellite mission dedicated to the study of Polar Mesospheric Clouds (PMCs). A Pegasus XL rocket placed the AIM satellite into a near circular (601 km apogee, 595 km perigee), 12:00 AM/PM sun-synchronous orbit. By measuring PMCs and the thermal, chemical and dynamical environment in which they form, AIM will quantify the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of long-term variability in mesospheric climate and its relationship to global change. The results of AIM will be a rigorous test and validation of predictive models that then can reliably use past PMC changes and current data to assess trends as indicators of global change. This goal is being achieved by measuring PMC densities, spatial distribution, particle size distributions, gravity wave activity, meteoric smoke influx to the atmosphere and vertical profiles of temperature, H2O, O3, CH4, NO, and CO2. <br />
<br />
The overall goal of AIM is to resolve why PMCs form and why they vary. It has been suggested that the observed changes in the clouds are related to increased concentrations of greenhouse gases. This suggestion is plausible because an increase in carbon dioxide, while warming the surface of the Earth, cools the upper atmosphere which can facilitate mesospheric cloud formation there. Additionally, increases in methane at the surface of the Earth lead to increases in water vapor at high altitudes through chemical oxidation processes, which further facilitates cloud formation and growth. While plausible, this greenhouse gas hypothesis has not yet been proven.The AIM webpage is at [http://aim.hamptonu.edu/]<br />
<br />
<br />
----<br />
<br />
== Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) ==<br />
[[File:alomar-rmr-lidar-small.png|left|Fig. 1:ALOMAR observatory and laser beams of the ALOMAR RMR-lidar during operation with tilted telescopes (courtesy, J. Fiedler)]] [[File:rmr-timeseries-small.png|right|]]Fig. 2:Year-to-year variability of seasonal mean NLC occurrence and altitude for two different cloud classes. The blue curves contain all measurements having a sensitivity above the long-term detection limit, whereas the green curves show results for strong clouds only. The vertical bars indicate 95% confidence limits for the occurrence and errors of the mean altitudes. For more information see text and references.<br />
The Rayleigh/Mie/Raman (RMR) lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) is located on top of a ≈400 m high mountain in Northern Norway (69.3°N, 16.0°E). It was installed in 1994 and designed for multi-parameter investigations of the Arctic middle atmosphere on a climatological basis. Because of its Arctic location, the lidar is optimized for measurements during full sunlight. Appropriate technical solutions, laser wavelength stabilization in combination with strong spectral as well as spatial filtering at the receiving system, have been implemented. The lidar is a complex twin-system consisting of two power lasers, two receiving telescopes, and one optical bench for spectral separation and filtering of the light received from the atmosphere. The lasers emit pulses at three wavelengths (355 nm, 532 nm, 1064 nm) simultaneously with an overall peak power of 150 MW per laser. The backscattered light from the atmosphere is collected by telescopes with a diameter of 1.8 m each. They can be tilted up to 30° off-zenith to allow different viewing directions (Fig. 1), which separates the sounding volume up to 90 km at an altitude of 80 km. After spectral and intensity separation the light is analyzed by 15 channels and recorded by single photon counting detectors. <br />
One main objective of the RMR-lidar is the observation of ice layers in the mesopause region, which are known as noctilucent clouds (NLC) and polar mesospheric clouds (PMC). Throughout the NLC season (1 June to 15 August) the lidar is operational for 24 hours per day to measure whenever permitted by the local weather conditions. This yielded a total of more than 4000 measurement hours from 1997 to 2009. NLC were observed during ≈1700 hours which is the largest NLC data base acquired by lidar. The data are used to investigate decadal scale changes of NLC parameters, size and number density of the ice particles, as well as small scale structures which are often observed in the cloud layers. Fig. 2 shows the time series of NLC occurrence and altitude above ALOMAR covering one solar cycle (taken from reference 2). During these 11 years there is no statistical significant anti-correlation between cloud occurrence and solar activity, which is partly in contrast to other data sets. The mean cloud altitude is 83.2 km and appears to remain nearly unchanged since the first NLC observations more than 100 years ago.<br />
----<br />
<br />
==Visual Observations of Noctilucent Clouds ==<br />
<br />
<br />
<br />
[[File:2005-06-24_213509-GB-2005-06-24_213551-GB-sm.png|center|Fig. 1:Noctilucent cloud display seen from Kühlungsborn, Germany, on June 24, 2005 while the sun is about 8 degrees below the horizon. (courtesy, G. Baumgarten)]] Scientific interest in noctilucent clouds (NLC) can be traced back to 1884 when many observers watched the twilight sky to see the dramatic sunsets caused by dust from Krakatoa, which had erupted during the previous year. Captivating displays of 'night shining' clouds, were seen and quickly recognized as lying at much higher altitude than normal clouds. For much of the 20th century, visual and photographic observations were the only methods available for systematic monitoring of NLC characteristics. By the early 1960's it was clear that their occurrence rates varied enormously from year to year. Widespread, intense displays of NLC were seen for a few consecutive summers, with NLC reported from somewhere around the 50 - 60 N latitude band almost every night over the summer season. These periods were followed by years when almost no NLC at all were seen. The most notable 'high spots' for NLC were the years 1885-1890 and 1963-1968, which were each followed by strong declines in NLC reports even though the same observers as during the 'hot spots' continued to look for them (reference 1).<br />
<br />
Starting with the International Geophysical Year in 1958, professionally organized observing networks started to gather systematic records of visual sightings of noctilucent clouds (see references). Even though professional involvement has generally ended, or become sporadic, systematic NLC observations are still collected by networks of enthusiasts, in Europe, Russia, Canada and North America. Since 1996, visual observations by members of the public are collected at a number of regional or national centers [http://www.kersland.plus.com/nlcrepor.htm#nlccanam], and since 1996 at the 'Noctilucent Cloud Observers Homepage' [ http://www.kersland.plus.com/]. NLC observations from the UK and Denmark since 1964 form the longest continuous record (observing latitudes from 51 - 61 N). These show how NLC are most common in years of low solar activity, and rare in years of high solar activity. They do not show any significant increase over the last 45 years although a few percent increase (or decrease) cannot be ruled out (Fig. 2, reference 3).<br />
[[File:NLC_UK_Denmark.png|200px|thumb|right|Fig. 2 A comparison of solar activity and the seasonal NLC frequency of occurrence according to reports of visual observations from the UK and Denmark (from Reference 3, extended to 2009 using internet reports [http://www.kersland.plus.com/]) ]]<br />
<br />
Although monitoring of large-scale structures and possible trends in NLC is being taken over by satellite measurements, visual and photographic observations still have an important role to play. For example, they are the best method available for studying fine-scale structure, on scales of 10s of km or less, and they can be instrumental in identifying NLC at unusually low latitudes where satellites observations and ground-based remote sensing instruments are not available. <br />
<br />
[[File:2005-06-24_213509-GB-sm.jpg|left|Fig. 3:Wave structures on scales of several km are often seen in noctilucent cloud and highlight the dynamical processes leading to the cold summer mesopause. (courtesy, G. Baumgarten)]] <br />
<br />
#Fogle,B.and B.Haurwitz,Long term variations in noctilucent cloud activity and their possible cause, in Climatological Research,edited by K.Fraedrich, M.Hantel,H.Claussen Korff,and E.Ruprecht,pp. 263–276,Heft 7,Bonner Meteorologische Abhandlungen.,Bonn,Germany,1974. <br />
#Romejko, V.A., P.A. Dalin, N.N. Pertsev, Forty years of Noctilucent Clouds observations near Moscow: database and simple statistics, J. Geophys. Res., 108, D8, 8443, doi: 10.1029/2002JD002364, 2003.<br />
#Kirkwood, S., P. Dalin, A. Rechou, Noctilucent clouds observed from the UK and Denmark – trends and variations over 43 years, Annales Geophysicae, 26, 1243-1254, 2008.<br />
----<br />
<br />
<br />
<br />
== Additional notes about NLC long-term behavior according to visual observations ==<br />
<br />
<br />
1. There is no distinct contradiction when comparing a trend in the NLC occurrence frequency from ground-based observations and a trend in the PMC satellite observations for lower latitudes (50-64°N), if we take the same years for an analysis. The difference between the NLC and PMC trend is rather in their significance probability. However, if we consider ground-based NLC observations for more than 40 years (which are longer than space-borne measurements) we arrive at almost zero trend in the NLC occurrence frequency and at very small positive trend in the NLC brightness which have no statistical significance.<br />
<br />
[[File:Pertsevfig_1.png|200px|thumb|right|Fig. 1 Residuals (after subtracting the variation correlated with the solar Lyman alpha flux) of the normalized NLC frequency. The thick line represents the secular trend and its 95% confidence interval. The upper panel demonstrates the Moscow linear fit for 1962–2005, the central panel is for the Moscow linear fit for 1983–2005 and the lower panel is for the Danish data for 1983–2005 (courtesy N. N. Pertsev).]]<br />
<br />
2. NLC most frequently occur in 1-2 years after the sunspot minimum and this delay is statistically significant. The PMC observations show a smaller delay of 0.5±0.5 year.<br />
<br />
3. Concerning the year of the NLC discovery, we should note the following. The majority of papers, devoted to first observations of noctilucent clouds, refer not to 1884 but to 1885 as a year of first reliable descriptions undoubtedly concerning noctilucent clouds. Leslie (1884) did describe some sky phenomenon, resembling noctilucent clouds, but in his successive papers, Leslie (1885) and (1886), devoted to luminous clouds as a new phenomenon, he wrote nothing about priority of that observation of 1884; moreover, he did not refer to it at all. So, the description of Leslie's observation of 1884 cannot be regarded as reliable. Summarizing, Gadsden and Schröder (1989) wrote in their canonical book: “…It is certain that at the times of coloured twilight appearances of 1883/1884, no noctilucent clouds were discovered. Various reports also exist which could be interpreted as noctilucent clouds, but this will always remain uncertain (Pernter 1889; Schröder 1975; Gadsden 1985).”. <br />
<br />
References:<br />
<br />
#Dalin, P., S. Kirkwood, H. Andersen, O. Hansen, N. Pertsev, V. Romejko, Comparison of long-term Moscow and Danish NLC observations: statistical results, Annales Geophysicae, 24, 2841-2849, 2006.<br />
#Leslie, R., 1884. The sky-glows. Nature 30, 583.<br />
#Leslie, R., 1885. Sky glows. Nature 32, 245.<br />
#Leslie, R., 1886. Luminous clouds. Nature 34, 264.<br />
<br />
P. Dalin, N. Pertsev</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2012-05-13T19:39:39Z<p>Marsh: /* MEETING AGENDA (As of April 30, 2012) */</p>
<hr />
<div>* Project leaders: G.Thomas (USA), U.Berger (Germany)<br />
* Project members: S. Bailey (USA),G. Baumgarten(Germany),M. DeLand (USA), J. Fiedler (Germany),B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), F.-J. Lübken (Gemany), A. Merkel (USA), N. Pertsev (Russia), J. Russell III (USA), E. Shettle (USA)<br />
==Introduction==<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year time series of SBUV (Solar Backscatter Ultraviolet) satellite measurements (see Figure 1). SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable. It is important to understand the relative roles of these three factors (solar, inter-annual and long-term forcing) before a definitive long-term trend can be evaluated. Furthermore the problem of attribution, that is, the nature of the various forcings on ice formation is not yet understood. For example with respect to the long-term changes, is a lowered temperature due to higher carbon dioxide responsible for the observed increase in brightness and occurrence frequency of MC? Or are water vapor changes due to oxidation of methane responsible, since we know that lower atmospheric methane has more than doubled over the past 120 years, and methane oxidation leads to upper atmospheric water vapor. The failure to detect any changes in the altitude of MC since the first measurement made by Otto Jesse in the late nineteenth century has provided an important constraint, since water vapor changes and temperature changes affect cloud altitude in different ways. Fortunately, the state of the art in modeling has now reached a point where ice formation is coupled with general circulation models. In a recent study Berger and Lübken (2011) showed that in the summer period 1979 -1997 at mid-latitudes strong cooling of up to 3-4 K/decade occurs in the middle mesosphere, in the period 1961-1979 the middle atmosphere cooled significantly less, and for the period 1997-2009 they find a warming of ~1 K/decade. For the first time, modeled temperature trends confirm the extraordinarily large temperature trends observed at mid-latitudes during the period 1979-1997 derived from lidar measurements, satellite data, and phase height measurements. The differences in temperature trends in the mesosphere originate from the evolution of stratospheric ozone in the past 50 years, e.g. the observed reversal of both stratospheric and mesospheric temperature trends in the mid 1990s is caused by the recovery of <br />
stratospheric ozone (WMO report 2011). Therefore a new research question arises: does any trend in MC show a similar behavior? Relevant publications on this subject are reported in the references below:<br />
[[File:Vqn-fig2rev.png|thumb|Fig. 1 A comparison of the seasonal PMC frequency of occurrence measured by SBUV and the fit to a linear regression in time and solar activity (upper panel) by latitude band and (lower panel) for all latitude bands combined between 54°N and 82°N. The error bars are the confidence limits in the individual seasonal mean values based on counting statistics, which do not reflect other factors such as inter-annual variability in large scale dynamics (from Reference 5)]]<br />
<br />
==References==<br />
<br />
#Luebken, F.-J., U. Berger, and G. Baumgarten (2009), Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds, J. Geophys. Res., 114, D00I06, doi:10.1029/2009JD012377 <br />
#Merkel, A. W., Marsh, D. R., Gettelman, A., and Jensen, E. J.: On the relationship of polar mesospheric cloud ice water content, particle radius and mesospheric temperature and its use in multi-dimensional models, Atmos. Chem. Phys., 9, 8889-8901, 2009<br />
# Merkel, A. W., D. Marsh, G. E. Thomas, C. Bardeen, M. Deland, WACCM simulations of long-term changes in polar mesospheric clouds, Layered Phenomenon in Mesospheric Regions (LPMR) Conference, Stockholm, 2009<br />
#Marsh, D and A. W. Merkel, 30-year PMC variability modeled by WACCM, SA33B-08, Fall AGU Meeting, San Francisco, 2009<br />
#Shettle,E. P.,M. T. DeLand, G. E. Thomas, and J. J. Olivero (2009), Long term variations in the frequency of polar mesospheric clouds in the Northern Hemisphere from SBUV, Geophys. Res. Lett., 36, L02803, doi:10.1029/2008GL036048.<br />
#Thomas, G. E., D. Marsh and F.-J. Lübken, Mesospheric ice clouds as indicators of upper atmosphere climate change, EOS, Transactions, American Geophysical Union, 91, No. 20, 18 May 2010, p. 183.<br />
#Berger, U., and F.-J. Lübken (2011), Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., 38, L22804, doi: 10.1029/2011GL049528.<br />
#WMO (2011), Global ozone research and monitoring project-Report no. 52, Scientific assessment of ozone depletion: 2010, World Meteorological Organization<br />
<br />
<br />
=Workshops and Meetings=<br />
The first workshop under the auspices of this working group was held in Boulder, Colorado on December 10 & 11, 2010, entitled Modeling Trends in mesospheric clouds (Thomas et al, 2010).<br />
[[file:COSTEP_LOGO_240.gif|left|]]<br />
==[[Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012]]==<br />
<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, USA.<br />
<br />
We announce here a forthcoming workshop to be held in Boulder, CO USA on May 3-4, 2012. This is the 7th workshop sponsored by IAGA/ICMA/CAWSES and focusses on global change in the upper mesosphere, specifically decadal-scale trends in Polar Mesospheric Clouds, PMC (or Noctilucent Clouds, NLC, as they are traditionally called when observed from the ground at twilight).<br />
<br />
The issue of long-term changes in PMC was addressed in the first workshop in Boulder, Colorado, 10-11 December, 2009 (Thomas et al, 2010). A long suite of satellite measurements by the Solar Backscatter Ultraviolet Spectrometer (SBUV) dating back to 1979 shows a significant long-term trend in mesospheric cloud activity and brightness. Attribution of trends in these high-altitude ice clouds (~83 km) includes: (1) increasing carbon dioxide concentrations which tend to cool the upper mesosphere (the 80-90 km 'mesopause region'); (2) increasing water vapor due to growing concentrations of methane, in addition to changing efficiency of tropospheric water vapor entry through the tropopause; (3) shrinking of the upper atmosphere arising largely from decreased ozone levels and subsequent stratospheric cooling; (4) increased concentrations of water vapor due to the rise in space traffic over the last 30 years. Other possible causes are long-term changes in winds and wind filtering of gravity waves which dominate the dynamics of the high-latitude summertime mesopause region. An even larger (cyclic) trend is superimposed on the long-term record, believed to be a result of the solar cycle, but not well understood.<br />
<br />
General circulation models coupled with ice formation are now capable of simulating the SBUV trends to a remarkable degree, as discussed in the first workshop. However, new modeling results have brought out the importance of ozone trends, which affect the heat balance of the entire upper atmosphere. The LIMA/ICE model predicts a 'break-point' in the time series of PMC trends, due to the turn-around of the ozone trend in the mid-1990's. A wealth of new data from several satellite missions (AIM, ODIN, TIMED) are available. The Aeronomy of Ice in the Mesosphere (AIM) directly addresses the processes which control ice cloud evolution. In addition, more information is now available on diurnal variations in ice water content, which in principle affects the analysis of trends made from satellites in sun-synchronous orbits with slowly-varying local time coverage. These and other advances in modeling, data availability and trend analysis are motivations for a coming together of both modelers and data analysts to assess the current state of knowledge. A goal of the workshop would be to make recommendations for future work to resolve many of the outstanding issues.<br />
<br />
The PMC Trend Workshop will be held at the Laboratory for Atmospheric Physics at the Space Science Building, the newest LASP location at the University Research Campus Park, University of Colorado, Boulder, Co, USA on May 3 and 4, 2012. All interested researchers, and particularly students, are invited to the meeting. No registration fees will be charged. We have now committed the travel funds allocated to us by CAWSES.<br />
<br />
Gary Thomas (thomas@lasp.colorado.edu) and Uwe Berger (berger@iap-kborn.de), co-chairs of CAWSES-II, Task 2, Project 3<br />
<br />
<br />
<br />
===MEETING AGENDA===<br />
<br />
==AM Thursday, May 3== <br />
<br />
0830-0840: Gary Thomas, LASP<br />
Welcome & Summary of Workshop Objectives<br />
<br />
====[[Long-term Trends: PMC Observations]]====<br />
0840-0900<br />
John Olivero, Embry-Riddle University, USA, Some Historical Notes on Noctilucent Cloud Studies<br />
<br />
0900-0910 Q&A, and discussion<br />
<br />
0910-0930 Matthew DeLand, SSAI, USA,Current PMC Trends Derived from SBUV Measurements<br />
<br />
0930-0940 Q&A, and discussion<br />
<br />
0940-1000 Mark Zalcik, Coordinator, NLC Can Am Network, Canada,Two Decades of Noctilucent Cloud Monitoring in North America<br />
<br />
1000-1010 Q&A, and discussion<br />
<br />
1010-1025 P. Dalin, Swedish Institute of Space Physics, Sweden,On the long-term trends in noctilucent clouds as observed from the ground and on the trends in the OH summer temperature as measured in Moscow and Lithuania<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
1100-1120 Gerd Baumgarten, IUP, Germany,Decadal observations of particle sizes and water vapor content of NLC<br />
<br />
1120-1130 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Temperature & Water Vapor Observations]]====<br />
<br />
1130-1150 Alain Hauchecorne, Laboratoire ATmosphères, France, Temperature trends in the stratosphere and in the mesosphere as seen from Rayleigh lidar observations<br />
<br />
1150-1200 Q&A, and discussion<br />
<br />
1200-1220 Karen Rosenlof, NOAA, USA , A new satellite based zonally averaged time series of stratospheric water vapor<br />
<br />
1220-1230 Q&A, and discussion<br />
<br />
1230-1330 Lunch Break<br />
<br />
==PM Thursday, May 3==<br />
<br />
====[[ Long-term Trends: Temperature & Water Vapor Observations (cont.)]]====<br />
<br />
1330-1350 Gerald Nedoluha, NRL, USA , Long-Term Ground-based Microwave Measurements of Middle Atmospheric Water Vapor from NDACC sites<br />
<br />
1350-1400 Q&A, and discussion<br />
<br />
1400-1420 Michael Stevens, NRL, USA ,The impact of space shuttle main engine exhaust on PMCs and implications to trend studies<br />
<br />
1420-1430 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Modeling]]====<br />
<br />
1430-1450 Uwe Berger, IUP, Germany,Solar variability and trend effects in mesospheric ice layers<br />
<br />
1450-1500 Q&A, and discussion<br />
<br />
1500-1520 Aimee Merkel, LASP, USA,WACCM-PMC simulations of long-term trends of PMC<br />
<br />
1520-1530 Q&A, and discussion<br />
<br />
1530-1600 Coffee Break<br />
<br />
1600-1620 David Siskind, NRL, USA,The PMC region as an integrator of coupling processes: Implications for trend studies from AIM and other missions<br />
<br />
1620-1630 Q&A, and discussion<br />
<br />
1630-1650 Stan Solomon, NCAR, USA,Thermospheric Temperature Trends: Modeling and Observations<br />
<br />
1650-1700 Q&A and discussion<br />
<br />
1700-1720 Dan Marsh, NCAR, USA,Climate change in the mesosphere from 1850 to 2100 in CESM-WACCM<br />
<br />
1720-1730 Q&A, and discussion<br />
<br />
1730-1750 Kota Okamoto, The University of Tokyo, Japan, On the dynamical responses in the middle atmosphere to ozone recovery and CO2 increase<br />
<br />
1750-1800 Q&A, and discussion<br />
<br />
1800 Adjourn<br />
<br />
1900-2100 Group Dinner (TBD)<br />
<br />
==AM Friday, Friday, May 4==<br />
<br />
====[[Inter-annual, hemispheric and seasonal variability: Observations]]====<br />
<br />
0830-0850 James Russell III, Hampton Univ, USA, AIM science results and their significance for PMC long-term change studies<br />
<br />
0850-0900 Q&A, and discussion <br />
<br />
0900-0920 Cora Randall, LASP, USA, AIM/CIPS Observations of PMC Variability<br />
<br />
0920-0930 Q&A, and discussion<br />
<br />
0930-0945 Rachel Ward, Utah State University, USA, Comparison of Northern and Southern Hemisphere Mesospheric Gravity Waves using CIPS PMC Data<br />
<br />
0945-0950 Q&A, and discussion<br />
<br />
0950-1005 Susanne Benze, LASP, USA, On the onset of polar mesospheric cloud seasons<br />
<br />
1005-1010 Q&A, and discussion<br />
<br />
1010-1025 Hanli Liu, NCAR, USA ,Fast meridional transport in the lower thermosphere by planetary-scale waves<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
====[[Properties of PMC and their Environment: Observations]]====<br />
<br />
1100-1115 E.J. Llewellyn, University of Saskatchewan, Canada, Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb<br />
<br />
1115-1120 Q&A, and discussion<br />
<br />
1120-1135 Scott Robertson, U of Colorado, USA, Detection of Meteoric Dust in Mesosphere by the CHAMPS Rockets<br />
<br />
1135-1140 Q&A, and discussion<br />
<br />
1140-1200 Kristell Pérot, LATMOS Laboratoire ATmosphères, France, PMC Particle Size Retrieval from GOMOS / ENVISAT Observations<br />
<br />
1200 -1210 Q&A and discussion<br />
<br />
1210-1310 Lunch<br />
<br />
==PM Friday, Friday, May 4==<br />
<br />
====[[Properties of PMC and their Environment: Modeling]]====<br />
<br />
1310-1330 Charles Bardeen, NCAR, USA, Simulations of PMC during the AIM time period using WACCM/CARMA<br />
<br />
1330-1340 Q&A, and discussion<br />
<br />
1340-1400 Mark Hervig, GATS, Inc., Variability in PMCs and their environment from SOFIE observations, and potential implications for PMC trends<br />
<br />
1400-1410 Q&A, and discussion<br />
<br />
1410-1425 I. Azeem, Astraspace, USA, Simulations of Shuttle Main Engine Plume Effects on Lower Thermosphere Energetics and Chemistry<br />
<br />
1425-1430 Q&A, and discussion<br />
<br />
1430-1445 Coffee Break<br />
<br />
Panel and group discussion<br />
<br />
1445-1545 Panel discussion<br />
<br />
1545-1630 Concluding remarks & summary from the project co-chairs<br />
<br />
1630 Adjourn<br />
<br />
==Local Organizing Committee: Aimee.Merkel@lasp.colorado.edu,Dan Marsh (marsh@ucar.edu) and Charles Bardeen (bardeenc@ucar.edu)==<br />
<br />
===NOTE: The Particle Size Workshop,originally scheduled for May 2, has been postponed to a later date.===<br />
<br />
==SPECIAL JOURNAL ISSUE ON UPPER ATMOSPHERIC TRENDS NOW AVAILABLE. The joint JGR/Space, JGR/Atmospheres special section on upper atmospheric trends is now complete, and can be accessed at http://www.agu.org/journals/ja/special_sections.shtml?collectionCode=UATREND1&amp;journalCode=JA==<br />
<br />
='''Observing Facilities'''=<br />
<br />
<br />
== Aeronomy of Ice in the Mesosphere (AIM), a NASA satellite mission (2007-) ==<br />
[[File:AIMforWIKI.png|left|Fig. 2 Artist's conception of the AIM spacecraft in orbit, showing the line of sight of the SOFIE solar occultation experiment (courtesy, J. Russell III]][[File:CIPSfig1.png|right|]]AIM was launched from Vandenberg Air Force Base on April 25, 2007 becoming the first satellite mission dedicated to the study of Polar Mesospheric Clouds (PMCs). A Pegasus XL rocket placed the AIM satellite into a near circular (601 km apogee, 595 km perigee), 12:00 AM/PM sun-synchronous orbit. By measuring PMCs and the thermal, chemical and dynamical environment in which they form, AIM will quantify the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of long-term variability in mesospheric climate and its relationship to global change. The results of AIM will be a rigorous test and validation of predictive models that then can reliably use past PMC changes and current data to assess trends as indicators of global change. This goal is being achieved by measuring PMC densities, spatial distribution, particle size distributions, gravity wave activity, meteoric smoke influx to the atmosphere and vertical profiles of temperature, H2O, O3, CH4, NO, and CO2. <br />
<br />
The overall goal of AIM is to resolve why PMCs form and why they vary. It has been suggested that the observed changes in the clouds are related to increased concentrations of greenhouse gases. This suggestion is plausible because an increase in carbon dioxide, while warming the surface of the Earth, cools the upper atmosphere which can facilitate mesospheric cloud formation there. Additionally, increases in methane at the surface of the Earth lead to increases in water vapor at high altitudes through chemical oxidation processes, which further facilitates cloud formation and growth. While plausible, this greenhouse gas hypothesis has not yet been proven.The AIM webpage is at [http://aim.hamptonu.edu/]<br />
<br />
<br />
----<br />
<br />
== Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) ==<br />
[[File:alomar-rmr-lidar-small.png|left|Fig. 1:ALOMAR observatory and laser beams of the ALOMAR RMR-lidar during operation with tilted telescopes (courtesy, J. Fiedler)]] [[File:rmr-timeseries-small.png|right|]]Fig. 2:Year-to-year variability of seasonal mean NLC occurrence and altitude for two different cloud classes. The blue curves contain all measurements having a sensitivity above the long-term detection limit, whereas the green curves show results for strong clouds only. The vertical bars indicate 95% confidence limits for the occurrence and errors of the mean altitudes. For more information see text and references.<br />
The Rayleigh/Mie/Raman (RMR) lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) is located on top of a ≈400 m high mountain in Northern Norway (69.3°N, 16.0°E). It was installed in 1994 and designed for multi-parameter investigations of the Arctic middle atmosphere on a climatological basis. Because of its Arctic location, the lidar is optimized for measurements during full sunlight. Appropriate technical solutions, laser wavelength stabilization in combination with strong spectral as well as spatial filtering at the receiving system, have been implemented. The lidar is a complex twin-system consisting of two power lasers, two receiving telescopes, and one optical bench for spectral separation and filtering of the light received from the atmosphere. The lasers emit pulses at three wavelengths (355 nm, 532 nm, 1064 nm) simultaneously with an overall peak power of 150 MW per laser. The backscattered light from the atmosphere is collected by telescopes with a diameter of 1.8 m each. They can be tilted up to 30° off-zenith to allow different viewing directions (Fig. 1), which separates the sounding volume up to 90 km at an altitude of 80 km. After spectral and intensity separation the light is analyzed by 15 channels and recorded by single photon counting detectors. <br />
One main objective of the RMR-lidar is the observation of ice layers in the mesopause region, which are known as noctilucent clouds (NLC) and polar mesospheric clouds (PMC). Throughout the NLC season (1 June to 15 August) the lidar is operational for 24 hours per day to measure whenever permitted by the local weather conditions. This yielded a total of more than 4000 measurement hours from 1997 to 2009. NLC were observed during ≈1700 hours which is the largest NLC data base acquired by lidar. The data are used to investigate decadal scale changes of NLC parameters, size and number density of the ice particles, as well as small scale structures which are often observed in the cloud layers. Fig. 2 shows the time series of NLC occurrence and altitude above ALOMAR covering one solar cycle (taken from reference 2). During these 11 years there is no statistical significant anti-correlation between cloud occurrence and solar activity, which is partly in contrast to other data sets. The mean cloud altitude is 83.2 km and appears to remain nearly unchanged since the first NLC observations more than 100 years ago.<br />
----<br />
<br />
==Visual Observations of Noctilucent Clouds ==<br />
<br />
<br />
<br />
[[File:2005-06-24_213509-GB-2005-06-24_213551-GB-sm.png|center|Fig. 1:Noctilucent cloud display seen from Kühlungsborn, Germany, on June 24, 2005 while the sun is about 8 degrees below the horizon. (courtesy, G. Baumgarten)]] Scientific interest in noctilucent clouds (NLC) can be traced back to 1884 when many observers watched the twilight sky to see the dramatic sunsets caused by dust from Krakatoa, which had erupted during the previous year. Captivating displays of 'night shining' clouds, were seen and quickly recognized as lying at much higher altitude than normal clouds. For much of the 20th century, visual and photographic observations were the only methods available for systematic monitoring of NLC characteristics. By the early 1960's it was clear that their occurrence rates varied enormously from year to year. Widespread, intense displays of NLC were seen for a few consecutive summers, with NLC reported from somewhere around the 50 - 60 N latitude band almost every night over the summer season. These periods were followed by years when almost no NLC at all were seen. The most notable 'high spots' for NLC were the years 1885-1890 and 1963-1968, which were each followed by strong declines in NLC reports even though the same observers as during the 'hot spots' continued to look for them (reference 1).<br />
<br />
Starting with the International Geophysical Year in 1958, professionally organized observing networks started to gather systematic records of visual sightings of noctilucent clouds (see references). Even though professional involvement has generally ended, or become sporadic, systematic NLC observations are still collected by networks of enthusiasts, in Europe, Russia, Canada and North America. Since 1996, visual observations by members of the public are collected at a number of regional or national centers [http://www.kersland.plus.com/nlcrepor.htm#nlccanam], and since 1996 at the 'Noctilucent Cloud Observers Homepage' [ http://www.kersland.plus.com/]. NLC observations from the UK and Denmark since 1964 form the longest continuous record (observing latitudes from 51 - 61 N). These show how NLC are most common in years of low solar activity, and rare in years of high solar activity. They do not show any significant increase over the last 45 years although a few percent increase (or decrease) cannot be ruled out (Fig. 2, reference 3).<br />
[[File:NLC_UK_Denmark.png|200px|thumb|right|Fig. 2 A comparison of solar activity and the seasonal NLC frequency of occurrence according to reports of visual observations from the UK and Denmark (from Reference 3, extended to 2009 using internet reports [http://www.kersland.plus.com/]) ]]<br />
<br />
Although monitoring of large-scale structures and possible trends in NLC is being taken over by satellite measurements, visual and photographic observations still have an important role to play. For example, they are the best method available for studying fine-scale structure, on scales of 10s of km or less, and they can be instrumental in identifying NLC at unusually low latitudes where satellites observations and ground-based remote sensing instruments are not available. <br />
<br />
[[File:2005-06-24_213509-GB-sm.jpg|left|Fig. 3:Wave structures on scales of several km are often seen in noctilucent cloud and highlight the dynamical processes leading to the cold summer mesopause. (courtesy, G. Baumgarten)]] <br />
<br />
#Fogle,B.and B.Haurwitz,Long term variations in noctilucent cloud activity and their possible cause, in Climatological Research,edited by K.Fraedrich, M.Hantel,H.Claussen Korff,and E.Ruprecht,pp. 263–276,Heft 7,Bonner Meteorologische Abhandlungen.,Bonn,Germany,1974. <br />
#Romejko, V.A., P.A. Dalin, N.N. Pertsev, Forty years of Noctilucent Clouds observations near Moscow: database and simple statistics, J. Geophys. Res., 108, D8, 8443, doi: 10.1029/2002JD002364, 2003.<br />
#Kirkwood, S., P. Dalin, A. Rechou, Noctilucent clouds observed from the UK and Denmark – trends and variations over 43 years, Annales Geophysicae, 26, 1243-1254, 2008.<br />
----<br />
<br />
<br />
<br />
== Additional notes about NLC long-term behavior according to visual observations ==<br />
<br />
<br />
1. There is no distinct contradiction when comparing a trend in the NLC occurrence frequency from ground-based observations and a trend in the PMC satellite observations for lower latitudes (50-64°N), if we take the same years for an analysis. The difference between the NLC and PMC trend is rather in their significance probability. However, if we consider ground-based NLC observations for more than 40 years (which are longer than space-borne measurements) we arrive at almost zero trend in the NLC occurrence frequency and at very small positive trend in the NLC brightness which have no statistical significance.<br />
<br />
[[File:Pertsevfig_1.png|200px|thumb|right|Fig. 1 Residuals (after subtracting the variation correlated with the solar Lyman alpha flux) of the normalized NLC frequency. The thick line represents the secular trend and its 95% confidence interval. The upper panel demonstrates the Moscow linear fit for 1962–2005, the central panel is for the Moscow linear fit for 1983–2005 and the lower panel is for the Danish data for 1983–2005 (courtesy N. N. Pertsev).]]<br />
<br />
2. NLC most frequently occur in 1-2 years after the sunspot minimum and this delay is statistically significant. The PMC observations show a smaller delay of 0.5±0.5 year.<br />
<br />
3. Concerning the year of the NLC discovery, we should note the following. The majority of papers, devoted to first observations of noctilucent clouds, refer not to 1884 but to 1885 as a year of first reliable descriptions undoubtedly concerning noctilucent clouds. Leslie (1884) did describe some sky phenomenon, resembling noctilucent clouds, but in his successive papers, Leslie (1885) and (1886), devoted to luminous clouds as a new phenomenon, he wrote nothing about priority of that observation of 1884; moreover, he did not refer to it at all. So, the description of Leslie's observation of 1884 cannot be regarded as reliable. Summarizing, Gadsden and Schröder (1989) wrote in their canonical book: “…It is certain that at the times of coloured twilight appearances of 1883/1884, no noctilucent clouds were discovered. Various reports also exist which could be interpreted as noctilucent clouds, but this will always remain uncertain (Pernter 1889; Schröder 1975; Gadsden 1985).”. <br />
<br />
References:<br />
<br />
#Dalin, P., S. Kirkwood, H. Andersen, O. Hansen, N. Pertsev, V. Romejko, Comparison of long-term Moscow and Danish NLC observations: statistical results, Annales Geophysicae, 24, 2841-2849, 2006.<br />
#Leslie, R., 1884. The sky-glows. Nature 30, 583.<br />
#Leslie, R., 1885. Sky glows. Nature 32, 245.<br />
#Leslie, R., 1886. Luminous clouds. Nature 34, 264.<br />
<br />
P. Dalin, N. Pertsev</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2012-05-13T19:39:16Z<p>Marsh: /* Registration */</p>
<hr />
<div>* Project leaders: G.Thomas (USA), U.Berger (Germany)<br />
* Project members: S. Bailey (USA),G. Baumgarten(Germany),M. DeLand (USA), J. Fiedler (Germany),B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), F.-J. Lübken (Gemany), A. Merkel (USA), N. Pertsev (Russia), J. Russell III (USA), E. Shettle (USA)<br />
==Introduction==<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year time series of SBUV (Solar Backscatter Ultraviolet) satellite measurements (see Figure 1). SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable. It is important to understand the relative roles of these three factors (solar, inter-annual and long-term forcing) before a definitive long-term trend can be evaluated. Furthermore the problem of attribution, that is, the nature of the various forcings on ice formation is not yet understood. For example with respect to the long-term changes, is a lowered temperature due to higher carbon dioxide responsible for the observed increase in brightness and occurrence frequency of MC? Or are water vapor changes due to oxidation of methane responsible, since we know that lower atmospheric methane has more than doubled over the past 120 years, and methane oxidation leads to upper atmospheric water vapor. The failure to detect any changes in the altitude of MC since the first measurement made by Otto Jesse in the late nineteenth century has provided an important constraint, since water vapor changes and temperature changes affect cloud altitude in different ways. Fortunately, the state of the art in modeling has now reached a point where ice formation is coupled with general circulation models. In a recent study Berger and Lübken (2011) showed that in the summer period 1979 -1997 at mid-latitudes strong cooling of up to 3-4 K/decade occurs in the middle mesosphere, in the period 1961-1979 the middle atmosphere cooled significantly less, and for the period 1997-2009 they find a warming of ~1 K/decade. For the first time, modeled temperature trends confirm the extraordinarily large temperature trends observed at mid-latitudes during the period 1979-1997 derived from lidar measurements, satellite data, and phase height measurements. The differences in temperature trends in the mesosphere originate from the evolution of stratospheric ozone in the past 50 years, e.g. the observed reversal of both stratospheric and mesospheric temperature trends in the mid 1990s is caused by the recovery of <br />
stratospheric ozone (WMO report 2011). Therefore a new research question arises: does any trend in MC show a similar behavior? Relevant publications on this subject are reported in the references below:<br />
[[File:Vqn-fig2rev.png|thumb|Fig. 1 A comparison of the seasonal PMC frequency of occurrence measured by SBUV and the fit to a linear regression in time and solar activity (upper panel) by latitude band and (lower panel) for all latitude bands combined between 54°N and 82°N. The error bars are the confidence limits in the individual seasonal mean values based on counting statistics, which do not reflect other factors such as inter-annual variability in large scale dynamics (from Reference 5)]]<br />
<br />
==References==<br />
<br />
#Luebken, F.-J., U. Berger, and G. Baumgarten (2009), Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds, J. Geophys. Res., 114, D00I06, doi:10.1029/2009JD012377 <br />
#Merkel, A. W., Marsh, D. R., Gettelman, A., and Jensen, E. J.: On the relationship of polar mesospheric cloud ice water content, particle radius and mesospheric temperature and its use in multi-dimensional models, Atmos. Chem. Phys., 9, 8889-8901, 2009<br />
# Merkel, A. W., D. Marsh, G. E. Thomas, C. Bardeen, M. Deland, WACCM simulations of long-term changes in polar mesospheric clouds, Layered Phenomenon in Mesospheric Regions (LPMR) Conference, Stockholm, 2009<br />
#Marsh, D and A. W. Merkel, 30-year PMC variability modeled by WACCM, SA33B-08, Fall AGU Meeting, San Francisco, 2009<br />
#Shettle,E. P.,M. T. DeLand, G. E. Thomas, and J. J. Olivero (2009), Long term variations in the frequency of polar mesospheric clouds in the Northern Hemisphere from SBUV, Geophys. Res. Lett., 36, L02803, doi:10.1029/2008GL036048.<br />
#Thomas, G. E., D. Marsh and F.-J. Lübken, Mesospheric ice clouds as indicators of upper atmosphere climate change, EOS, Transactions, American Geophysical Union, 91, No. 20, 18 May 2010, p. 183.<br />
#Berger, U., and F.-J. Lübken (2011), Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., 38, L22804, doi: 10.1029/2011GL049528.<br />
#WMO (2011), Global ozone research and monitoring project-Report no. 52, Scientific assessment of ozone depletion: 2010, World Meteorological Organization<br />
<br />
<br />
=Workshops and Meetings=<br />
The first workshop under the auspices of this working group was held in Boulder, Colorado on December 10 & 11, 2010, entitled Modeling Trends in mesospheric clouds (Thomas et al, 2010).<br />
[[file:COSTEP_LOGO_240.gif|left|]]<br />
==[[Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012]]==<br />
<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, USA.<br />
<br />
We announce here a forthcoming workshop to be held in Boulder, CO USA on May 3-4, 2012. This is the 7th workshop sponsored by IAGA/ICMA/CAWSES and focusses on global change in the upper mesosphere, specifically decadal-scale trends in Polar Mesospheric Clouds, PMC (or Noctilucent Clouds, NLC, as they are traditionally called when observed from the ground at twilight).<br />
<br />
The issue of long-term changes in PMC was addressed in the first workshop in Boulder, Colorado, 10-11 December, 2009 (Thomas et al, 2010). A long suite of satellite measurements by the Solar Backscatter Ultraviolet Spectrometer (SBUV) dating back to 1979 shows a significant long-term trend in mesospheric cloud activity and brightness. Attribution of trends in these high-altitude ice clouds (~83 km) includes: (1) increasing carbon dioxide concentrations which tend to cool the upper mesosphere (the 80-90 km 'mesopause region'); (2) increasing water vapor due to growing concentrations of methane, in addition to changing efficiency of tropospheric water vapor entry through the tropopause; (3) shrinking of the upper atmosphere arising largely from decreased ozone levels and subsequent stratospheric cooling; (4) increased concentrations of water vapor due to the rise in space traffic over the last 30 years. Other possible causes are long-term changes in winds and wind filtering of gravity waves which dominate the dynamics of the high-latitude summertime mesopause region. An even larger (cyclic) trend is superimposed on the long-term record, believed to be a result of the solar cycle, but not well understood.<br />
<br />
General circulation models coupled with ice formation are now capable of simulating the SBUV trends to a remarkable degree, as discussed in the first workshop. However, new modeling results have brought out the importance of ozone trends, which affect the heat balance of the entire upper atmosphere. The LIMA/ICE model predicts a 'break-point' in the time series of PMC trends, due to the turn-around of the ozone trend in the mid-1990's. A wealth of new data from several satellite missions (AIM, ODIN, TIMED) are available. The Aeronomy of Ice in the Mesosphere (AIM) directly addresses the processes which control ice cloud evolution. In addition, more information is now available on diurnal variations in ice water content, which in principle affects the analysis of trends made from satellites in sun-synchronous orbits with slowly-varying local time coverage. These and other advances in modeling, data availability and trend analysis are motivations for a coming together of both modelers and data analysts to assess the current state of knowledge. A goal of the workshop would be to make recommendations for future work to resolve many of the outstanding issues.<br />
<br />
The PMC Trend Workshop will be held at the Laboratory for Atmospheric Physics at the Space Science Building, the newest LASP location at the University Research Campus Park, University of Colorado, Boulder, Co, USA on May 3 and 4, 2012. All interested researchers, and particularly students, are invited to the meeting. No registration fees will be charged. We have now committed the travel funds allocated to us by CAWSES.<br />
<br />
Gary Thomas (thomas@lasp.colorado.edu) and Uwe Berger (berger@iap-kborn.de), co-chairs of CAWSES-II, Task 2, Project 3<br />
<br />
<br />
<br />
===MEETING AGENDA (As of April 30, 2012)===<br />
<br />
==AM Thursday, May 3== <br />
<br />
0830-0840: Gary Thomas, LASP<br />
Welcome & Summary of Workshop Objectives<br />
<br />
====[[Long-term Trends: PMC Observations]]====<br />
0840-0900<br />
John Olivero, Embry-Riddle University, USA, Some Historical Notes on Noctilucent Cloud Studies<br />
<br />
0900-0910 Q&A, and discussion<br />
<br />
0910-0930 Matthew DeLand, SSAI, USA,Current PMC Trends Derived from SBUV Measurements<br />
<br />
0930-0940 Q&A, and discussion<br />
<br />
0940-1000 Mark Zalcik, Coordinator, NLC Can Am Network, Canada,Two Decades of Noctilucent Cloud Monitoring in North America<br />
<br />
1000-1010 Q&A, and discussion<br />
<br />
1010-1025 P. Dalin, Swedish Institute of Space Physics, Sweden,On the long-term trends in noctilucent clouds as observed from the ground and on the trends in the OH summer temperature as measured in Moscow and Lithuania<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
1100-1120 Gerd Baumgarten, IUP, Germany,Decadal observations of particle sizes and water vapor content of NLC<br />
<br />
1120-1130 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Temperature & Water Vapor Observations]]====<br />
<br />
1130-1150 Alain Hauchecorne, Laboratoire ATmosphères, France, Temperature trends in the stratosphere and in the mesosphere as seen from Rayleigh lidar observations<br />
<br />
1150-1200 Q&A, and discussion<br />
<br />
1200-1220 Karen Rosenlof, NOAA, USA , A new satellite based zonally averaged time series of stratospheric water vapor<br />
<br />
1220-1230 Q&A, and discussion<br />
<br />
1230-1330 Lunch Break<br />
<br />
==PM Thursday, May 3==<br />
<br />
====[[ Long-term Trends: Temperature & Water Vapor Observations (cont.)]]====<br />
<br />
1330-1350 Gerald Nedoluha, NRL, USA , Long-Term Ground-based Microwave Measurements of Middle Atmospheric Water Vapor from NDACC sites<br />
<br />
1350-1400 Q&A, and discussion<br />
<br />
1400-1420 Michael Stevens, NRL, USA ,The impact of space shuttle main engine exhaust on PMCs and implications to trend studies<br />
<br />
1420-1430 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Modeling]]====<br />
<br />
1430-1450 Uwe Berger, IUP, Germany,Solar variability and trend effects in mesospheric ice layers<br />
<br />
1450-1500 Q&A, and discussion<br />
<br />
1500-1520 Aimee Merkel, LASP, USA,WACCM-PMC simulations of long-term trends of PMC<br />
<br />
1520-1530 Q&A, and discussion<br />
<br />
1530-1600 Coffee Break<br />
<br />
1600-1620 David Siskind, NRL, USA,The PMC region as an integrator of coupling processes: Implications for trend studies from AIM and other missions<br />
<br />
1620-1630 Q&A, and discussion<br />
<br />
1630-1650 Stan Solomon, NCAR, USA,Thermospheric Temperature Trends: Modeling and Observations<br />
<br />
1650-1700 Q&A and discussion<br />
<br />
1700-1720 Dan Marsh, NCAR, USA,Climate change in the mesosphere from 1850 to 2100 in CESM-WACCM<br />
<br />
1720-1730 Q&A, and discussion<br />
<br />
1730-1750 Kota Okamoto, The University of Tokyo, Japan, On the dynamical responses in the middle atmosphere to ozone recovery and CO2 increase<br />
<br />
1750-1800 Q&A, and discussion<br />
<br />
1800 Adjourn<br />
<br />
1900-2100 Group Dinner (TBD)<br />
<br />
==AM Friday, Friday, May 4==<br />
<br />
====[[Inter-annual, hemispheric and seasonal variability: Observations]]====<br />
<br />
0830-0850 James Russell III, Hampton Univ, USA, AIM science results and their significance for PMC long-term change studies<br />
<br />
0850-0900 Q&A, and discussion <br />
<br />
0900-0920 Cora Randall, LASP, USA, AIM/CIPS Observations of PMC Variability<br />
<br />
0920-0930 Q&A, and discussion<br />
<br />
0930-0945 Rachel Ward, Utah State University, USA, Comparison of Northern and Southern Hemisphere Mesospheric Gravity Waves using CIPS PMC Data<br />
<br />
0945-0950 Q&A, and discussion<br />
<br />
0950-1005 Susanne Benze, LASP, USA, On the onset of polar mesospheric cloud seasons<br />
<br />
1005-1010 Q&A, and discussion<br />
<br />
1010-1025 Hanli Liu, NCAR, USA ,Fast meridional transport in the lower thermosphere by planetary-scale waves<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
====[[Properties of PMC and their Environment: Observations]]====<br />
<br />
1100-1115 E.J. Llewellyn, University of Saskatchewan, Canada, Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb<br />
<br />
1115-1120 Q&A, and discussion<br />
<br />
1120-1135 Scott Robertson, U of Colorado, USA, Detection of Meteoric Dust in Mesosphere by the CHAMPS Rockets<br />
<br />
1135-1140 Q&A, and discussion<br />
<br />
1140-1200 Kristell Pérot, LATMOS Laboratoire ATmosphères, France, PMC Particle Size Retrieval from GOMOS / ENVISAT Observations<br />
<br />
1200 -1210 Q&A and discussion<br />
<br />
1210-1310 Lunch<br />
<br />
==PM Friday, Friday, May 4==<br />
<br />
====[[Properties of PMC and their Environment: Modeling]]====<br />
<br />
1310-1330 Charles Bardeen, NCAR, USA, Simulations of PMC during the AIM time period using WACCM/CARMA<br />
<br />
1330-1340 Q&A, and discussion<br />
<br />
1340-1400 Mark Hervig, GATS, Inc., Variability in PMCs and their environment from SOFIE observations, and potential implications for PMC trends<br />
<br />
1400-1410 Q&A, and discussion<br />
<br />
1410-1425 I. Azeem, Astraspace, USA, Simulations of Shuttle Main Engine Plume Effects on Lower Thermosphere Energetics and Chemistry<br />
<br />
1425-1430 Q&A, and discussion<br />
<br />
1430-1445 Coffee Break<br />
<br />
Panel and group discussion<br />
<br />
1445-1545 Panel discussion<br />
<br />
1545-1630 Concluding remarks & summary from the project co-chairs<br />
<br />
1630 Adjourn<br />
<br />
==Local Organizing Committee: Aimee.Merkel@lasp.colorado.edu,Dan Marsh (marsh@ucar.edu) and Charles Bardeen (bardeenc@ucar.edu)==<br />
<br />
===NOTE: The Particle Size Workshop,originally scheduled for May 2, has been postponed to a later date.===<br />
<br />
==SPECIAL JOURNAL ISSUE ON UPPER ATMOSPHERIC TRENDS NOW AVAILABLE. The joint JGR/Space, JGR/Atmospheres special section on upper atmospheric trends is now complete, and can be accessed at http://www.agu.org/journals/ja/special_sections.shtml?collectionCode=UATREND1&amp;journalCode=JA==<br />
<br />
='''Observing Facilities'''=<br />
<br />
<br />
== Aeronomy of Ice in the Mesosphere (AIM), a NASA satellite mission (2007-) ==<br />
[[File:AIMforWIKI.png|left|Fig. 2 Artist's conception of the AIM spacecraft in orbit, showing the line of sight of the SOFIE solar occultation experiment (courtesy, J. Russell III]][[File:CIPSfig1.png|right|]]AIM was launched from Vandenberg Air Force Base on April 25, 2007 becoming the first satellite mission dedicated to the study of Polar Mesospheric Clouds (PMCs). A Pegasus XL rocket placed the AIM satellite into a near circular (601 km apogee, 595 km perigee), 12:00 AM/PM sun-synchronous orbit. By measuring PMCs and the thermal, chemical and dynamical environment in which they form, AIM will quantify the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of long-term variability in mesospheric climate and its relationship to global change. The results of AIM will be a rigorous test and validation of predictive models that then can reliably use past PMC changes and current data to assess trends as indicators of global change. This goal is being achieved by measuring PMC densities, spatial distribution, particle size distributions, gravity wave activity, meteoric smoke influx to the atmosphere and vertical profiles of temperature, H2O, O3, CH4, NO, and CO2. <br />
<br />
The overall goal of AIM is to resolve why PMCs form and why they vary. It has been suggested that the observed changes in the clouds are related to increased concentrations of greenhouse gases. This suggestion is plausible because an increase in carbon dioxide, while warming the surface of the Earth, cools the upper atmosphere which can facilitate mesospheric cloud formation there. Additionally, increases in methane at the surface of the Earth lead to increases in water vapor at high altitudes through chemical oxidation processes, which further facilitates cloud formation and growth. While plausible, this greenhouse gas hypothesis has not yet been proven.The AIM webpage is at [http://aim.hamptonu.edu/]<br />
<br />
<br />
----<br />
<br />
== Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) ==<br />
[[File:alomar-rmr-lidar-small.png|left|Fig. 1:ALOMAR observatory and laser beams of the ALOMAR RMR-lidar during operation with tilted telescopes (courtesy, J. Fiedler)]] [[File:rmr-timeseries-small.png|right|]]Fig. 2:Year-to-year variability of seasonal mean NLC occurrence and altitude for two different cloud classes. The blue curves contain all measurements having a sensitivity above the long-term detection limit, whereas the green curves show results for strong clouds only. The vertical bars indicate 95% confidence limits for the occurrence and errors of the mean altitudes. For more information see text and references.<br />
The Rayleigh/Mie/Raman (RMR) lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) is located on top of a ≈400 m high mountain in Northern Norway (69.3°N, 16.0°E). It was installed in 1994 and designed for multi-parameter investigations of the Arctic middle atmosphere on a climatological basis. Because of its Arctic location, the lidar is optimized for measurements during full sunlight. Appropriate technical solutions, laser wavelength stabilization in combination with strong spectral as well as spatial filtering at the receiving system, have been implemented. The lidar is a complex twin-system consisting of two power lasers, two receiving telescopes, and one optical bench for spectral separation and filtering of the light received from the atmosphere. The lasers emit pulses at three wavelengths (355 nm, 532 nm, 1064 nm) simultaneously with an overall peak power of 150 MW per laser. The backscattered light from the atmosphere is collected by telescopes with a diameter of 1.8 m each. They can be tilted up to 30° off-zenith to allow different viewing directions (Fig. 1), which separates the sounding volume up to 90 km at an altitude of 80 km. After spectral and intensity separation the light is analyzed by 15 channels and recorded by single photon counting detectors. <br />
One main objective of the RMR-lidar is the observation of ice layers in the mesopause region, which are known as noctilucent clouds (NLC) and polar mesospheric clouds (PMC). Throughout the NLC season (1 June to 15 August) the lidar is operational for 24 hours per day to measure whenever permitted by the local weather conditions. This yielded a total of more than 4000 measurement hours from 1997 to 2009. NLC were observed during ≈1700 hours which is the largest NLC data base acquired by lidar. The data are used to investigate decadal scale changes of NLC parameters, size and number density of the ice particles, as well as small scale structures which are often observed in the cloud layers. Fig. 2 shows the time series of NLC occurrence and altitude above ALOMAR covering one solar cycle (taken from reference 2). During these 11 years there is no statistical significant anti-correlation between cloud occurrence and solar activity, which is partly in contrast to other data sets. The mean cloud altitude is 83.2 km and appears to remain nearly unchanged since the first NLC observations more than 100 years ago.<br />
----<br />
<br />
==Visual Observations of Noctilucent Clouds ==<br />
<br />
<br />
<br />
[[File:2005-06-24_213509-GB-2005-06-24_213551-GB-sm.png|center|Fig. 1:Noctilucent cloud display seen from Kühlungsborn, Germany, on June 24, 2005 while the sun is about 8 degrees below the horizon. (courtesy, G. Baumgarten)]] Scientific interest in noctilucent clouds (NLC) can be traced back to 1884 when many observers watched the twilight sky to see the dramatic sunsets caused by dust from Krakatoa, which had erupted during the previous year. Captivating displays of 'night shining' clouds, were seen and quickly recognized as lying at much higher altitude than normal clouds. For much of the 20th century, visual and photographic observations were the only methods available for systematic monitoring of NLC characteristics. By the early 1960's it was clear that their occurrence rates varied enormously from year to year. Widespread, intense displays of NLC were seen for a few consecutive summers, with NLC reported from somewhere around the 50 - 60 N latitude band almost every night over the summer season. These periods were followed by years when almost no NLC at all were seen. The most notable 'high spots' for NLC were the years 1885-1890 and 1963-1968, which were each followed by strong declines in NLC reports even though the same observers as during the 'hot spots' continued to look for them (reference 1).<br />
<br />
Starting with the International Geophysical Year in 1958, professionally organized observing networks started to gather systematic records of visual sightings of noctilucent clouds (see references). Even though professional involvement has generally ended, or become sporadic, systematic NLC observations are still collected by networks of enthusiasts, in Europe, Russia, Canada and North America. Since 1996, visual observations by members of the public are collected at a number of regional or national centers [http://www.kersland.plus.com/nlcrepor.htm#nlccanam], and since 1996 at the 'Noctilucent Cloud Observers Homepage' [ http://www.kersland.plus.com/]. NLC observations from the UK and Denmark since 1964 form the longest continuous record (observing latitudes from 51 - 61 N). These show how NLC are most common in years of low solar activity, and rare in years of high solar activity. They do not show any significant increase over the last 45 years although a few percent increase (or decrease) cannot be ruled out (Fig. 2, reference 3).<br />
[[File:NLC_UK_Denmark.png|200px|thumb|right|Fig. 2 A comparison of solar activity and the seasonal NLC frequency of occurrence according to reports of visual observations from the UK and Denmark (from Reference 3, extended to 2009 using internet reports [http://www.kersland.plus.com/]) ]]<br />
<br />
Although monitoring of large-scale structures and possible trends in NLC is being taken over by satellite measurements, visual and photographic observations still have an important role to play. For example, they are the best method available for studying fine-scale structure, on scales of 10s of km or less, and they can be instrumental in identifying NLC at unusually low latitudes where satellites observations and ground-based remote sensing instruments are not available. <br />
<br />
[[File:2005-06-24_213509-GB-sm.jpg|left|Fig. 3:Wave structures on scales of several km are often seen in noctilucent cloud and highlight the dynamical processes leading to the cold summer mesopause. (courtesy, G. Baumgarten)]] <br />
<br />
#Fogle,B.and B.Haurwitz,Long term variations in noctilucent cloud activity and their possible cause, in Climatological Research,edited by K.Fraedrich, M.Hantel,H.Claussen Korff,and E.Ruprecht,pp. 263–276,Heft 7,Bonner Meteorologische Abhandlungen.,Bonn,Germany,1974. <br />
#Romejko, V.A., P.A. Dalin, N.N. Pertsev, Forty years of Noctilucent Clouds observations near Moscow: database and simple statistics, J. Geophys. Res., 108, D8, 8443, doi: 10.1029/2002JD002364, 2003.<br />
#Kirkwood, S., P. Dalin, A. Rechou, Noctilucent clouds observed from the UK and Denmark – trends and variations over 43 years, Annales Geophysicae, 26, 1243-1254, 2008.<br />
----<br />
<br />
<br />
<br />
== Additional notes about NLC long-term behavior according to visual observations ==<br />
<br />
<br />
1. There is no distinct contradiction when comparing a trend in the NLC occurrence frequency from ground-based observations and a trend in the PMC satellite observations for lower latitudes (50-64°N), if we take the same years for an analysis. The difference between the NLC and PMC trend is rather in their significance probability. However, if we consider ground-based NLC observations for more than 40 years (which are longer than space-borne measurements) we arrive at almost zero trend in the NLC occurrence frequency and at very small positive trend in the NLC brightness which have no statistical significance.<br />
<br />
[[File:Pertsevfig_1.png|200px|thumb|right|Fig. 1 Residuals (after subtracting the variation correlated with the solar Lyman alpha flux) of the normalized NLC frequency. The thick line represents the secular trend and its 95% confidence interval. The upper panel demonstrates the Moscow linear fit for 1962–2005, the central panel is for the Moscow linear fit for 1983–2005 and the lower panel is for the Danish data for 1983–2005 (courtesy N. N. Pertsev).]]<br />
<br />
2. NLC most frequently occur in 1-2 years after the sunspot minimum and this delay is statistically significant. The PMC observations show a smaller delay of 0.5±0.5 year.<br />
<br />
3. Concerning the year of the NLC discovery, we should note the following. The majority of papers, devoted to first observations of noctilucent clouds, refer not to 1884 but to 1885 as a year of first reliable descriptions undoubtedly concerning noctilucent clouds. Leslie (1884) did describe some sky phenomenon, resembling noctilucent clouds, but in his successive papers, Leslie (1885) and (1886), devoted to luminous clouds as a new phenomenon, he wrote nothing about priority of that observation of 1884; moreover, he did not refer to it at all. So, the description of Leslie's observation of 1884 cannot be regarded as reliable. Summarizing, Gadsden and Schröder (1989) wrote in their canonical book: “…It is certain that at the times of coloured twilight appearances of 1883/1884, no noctilucent clouds were discovered. Various reports also exist which could be interpreted as noctilucent clouds, but this will always remain uncertain (Pernter 1889; Schröder 1975; Gadsden 1985).”. <br />
<br />
References:<br />
<br />
#Dalin, P., S. Kirkwood, H. Andersen, O. Hansen, N. Pertsev, V. Romejko, Comparison of long-term Moscow and Danish NLC observations: statistical results, Annales Geophysicae, 24, 2841-2849, 2006.<br />
#Leslie, R., 1884. The sky-glows. Nature 30, 583.<br />
#Leslie, R., 1885. Sky glows. Nature 32, 245.<br />
#Leslie, R., 1886. Luminous clouds. Nature 34, 264.<br />
<br />
P. Dalin, N. Pertsev</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-05-13T19:38:27Z<p>Marsh: /* Past Meetings */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
CEDAR 2012 Workshop session on ''' Thermosphere and Ionosphere Climate'''<br />
[http://cedarweb.hao.ucar.edu/wiki/index.php/2012_Workshop:Thermosphere_and_Ionosphere_Climate]<br />
24-29 June 2012, Santa Fe, New Mexico, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on''' Long-Term Changes and Trends in the Atmosphere''', which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
Second CAWSES-2 Task 2 Workshop: '''Modeling Polar Mesospheric Cloud Trends''', May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-05-13T19:38:04Z<p>Marsh: /* Upcoming Meetings */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
CEDAR 2012 Workshop session on ''' Thermosphere and Ionosphere Climate'''<br />
[http://cedarweb.hao.ucar.edu/wiki/index.php/2012_Workshop:Thermosphere_and_Ionosphere_Climate]<br />
24-29 June 2012, Santa Fe, New Mexico, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on''' Long-Term Changes and Trends in the Atmosphere''', which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Project_2_The_enhancement_of_the_anthropogenic_effect_on_the_ionosphere/thermosphere_during_a_quiet_sun_period.Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.2012-04-18T17:05:39Z<p>Marsh: /* Introduction */</p>
<hr />
<div>* Project leaders: J. Emmert (USA), L. Qian (USA) <br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (USA), S. Nossal (USA), H. Schmidt (Germany), S.-R. Zhang (USA)<br />
<br />
==Introduction==<br />
The Earth's thermosphere (~90–800 km) is primarily heated by solar far and extreme ultraviolet (FUV and EUV) irradiance, and the primary cooling mechanism is downward conduction to the lower thermosphere and radiative cooling by CO2, NO, and O(3p) [Roble, 1995]. Increasing CO2 concentrations are therefore expected to result in enhanced cooling and consequent contraction of the thermosphere. Roble and Dickinson [1989] predicted that a doubling of CO2 would result in a 40% reduction in mass density at a height of 400 km. An overview of theoretical and empirical studies of mesospheric and thermospheric climate change is given by Laštovička et al. [2008]. <br />
<br />
Model studies [Qian et al., 2008] and satellite measurements [Emmert et al., 2008] suggest that the density trend in the upper thermosphere depends on solar activity and is larger for solar minimum conditions than for solar maximum conditions. One important mechanism of this dependency is that CO2 cooling is dominant during solar minimum, whereas NO cooling becomes relatively more important during solar maximum [Mlynczak et al., 2010]. Another mechanism is that density scale heights are smaller during cooler solar minimum conditions, so that further contraction of the thermosphere has a larger relative effect on density at a fixed height.<br />
<br />
Figure 1 shows measured density trends at 400 km, as a function of the F10.7 solar activity index, derived by Keating et al. [2000], Marcos et al. [2005], and Emmert et al. [2008], along with corresponding trends from theoretical simulations by Akmaev [2006] and Qian et al. [2006]. There is fairly good quantitative agreement among the empirical results. The theoretical trends from Qian et al. [2006] agree well with the observed trends in the interval 120 < F10.7 < 160, but the predicted trends at solar minimum are considerably smaller than the observed trends. Other mechanisms besides enhanced CO2 cooling may therefore be contributing to the observed solar minimum trends. The theoretical trend at 200 km computed by Akmaev et al. [2006], which represents moderate solar activity and includes the non-negligible effects of middle atmosphere ozone and water vapor trends, is much stronger than the observed trends under similar solar EUV conditions. <br />
<br />
Given the solar-cycle dependence of thermospheric long-term trends, it is reasonable to expect that the ionospheric long-term trends will also depend on solar activity. Qian et al. [2008, 2009] simulated the effects on the ionosphere of predicted CO2 increases from 2000 to 2100, under solar minimum and solar maximum conditions. The effect on F region parameters was larger under solar minimum conditions, similar to the solar-cycle dependence of secular change in the thermosphere. The solar cycle dependence of the response of E region parameters was less pronounced. To date, there has been no comprehensive assessment of the effect of the solar cycle on observed ionospheric trends.<br />
The goal of this CAWSES-II project is to understand how the response of the thermosphere/ionosphere to anthropogenic forcing differs between solar minimum and other phases of the solar cycle.<br />
<br />
[[File:trend.png|center|Fig. 1 Summary of observed and simulated thermospheric density trends at a height of 400 km, as a function of the F10.7 solar activity index. From Emmert et al. [2008]]]<br />
<br />
Figure 1. Summary of observed and simulated thermospheric density trends at a height of 400 km, as a function of the F10.7 solar activity index. From Emmert et al. [2008].<br />
<br />
<br />
== Upcoming Meetings ==<br />
<br />
CEDAR 2012 Workshop session on ''' Thermosphere and Ionosphere Climate'''<br />
[http://cedarweb.hao.ucar.edu/wiki/index.php/2012_Workshop:Thermosphere_and_Ionosphere_Climate]<br />
24-29 June 2012, Santa Fe, New Mexico, USA.<br />
<br />
==Research Plans==<br />
1) Compare CO2 and NO cooling rates from TIMED/SABER measurements with those predicted by TIME-GCM model simulations. Adjust the model cooling rates to match the data and determine the impact on thermospheric and ionospheric structure during the recent solar minimum.<br />
<br />
2) Analyze ionosonde parameters (from many stations) and Millstone Hill incoherent scatter radar (ISR) data for trends as a function of solar cycle. Compare with results from TIME-GCM model simulations.<br />
<br />
3) Compare HAMMONIA historical simulations (which assimilate lower atmospheric data) with TIME-GCM simulations of prescribed CO2 and CH4 increases, with particular focus on the conditions of the recent solar minimum.<br />
<br />
4) Use historical HAMMONIA model assimilations/simulations to estimate lower thermospheric temperature and composition anomalies since 1967, and thereby constrain the interpretation of height-dependent orbit-derived upper thermospheric density data. From the density data, estimate exospheric temperature trends as a function of solar cycle and compare with ion temperature trend results derived from the Millstone Hill ISR data. Investigate to what extent the estimated lower thermospheric anomalies can explain the unusually low upper thermospheric densities and temperatures of the recent solar minimum.<br />
<br />
5) Compare height-dependent orbit-derived thermospheric density data and inferred exospheric temperature with those predicted by TIME-GCM model simulations of CO2 and CH4 increases. Assess, via sensitivity tests, which factors might have contributed to the anomalously low densities and temperatures of the recent solar minimum.<br />
<br />
6) Analyze ground based observations of geocoronal Balmer-alpha emissions to determine whether there is a detectable trend in atomic hydrogen (an increase in upper thermospheric and geocoronal H has been predicted to occur as a result of CH4 increases). From model simulations, estimate how H trends might be modulated by the solar cycle. <br />
<br />
==References==<br />
#Akmaev, R. A., V. I. Fomichev, and X. Zhu (2006), Impact of middle-atmospheric composition changes on greenhouse cooling in the upper atmosphere, J. Atmos. Solar-Terr. Phys., 68, 1879–1889.<br />
#Emmert, J. T., J. M. Picone, and R. R. Meier (2008), Thermospheric global average density trends, 1967–2007, derived from orbits of 5000 near-Earth objects, Geophys. Res. Lett., 35, L05101, doi:10.1029/2007GL032809.<br />
#Emmert, J. T., J. L. Lean, and J. M. Picone (2010), Record-low thermospheric density during the 2008 solar minimum, Geophys. Res. Lett., 37, L12102, doi:10.1029/2010GL043671.<br />
#Keating, G. M., R. H. Tolson, and M. S. Bradford (2000), Evidence of long term global decline in the Earth's thermospheric densities apparently related to anthropogenic effects, Geophys. Res. Lett., 27, 1523–1526.<br />
#Laštovička, J., R. A. Akmaev, G. Beig, J. Bremer, J. T. Emmert, C. Jacobi, M. J. Jarvis, G. Nedoluha, Yu. I. Portnyagin, and T. Ulich (2008), Emerging pattern of global change in the upper atmosphere and ionosphere, Ann. Geophys., 26, 1255–1268.<br />
#Marcos, F. A., J. O. Wise, M. J. Kendra, N. J. Grossbard, and B. R. Bowman (2005), Detection of a long-term decrease in thermospheric neutral density, Geophys. Res. Lett., 32, L04103, doi:10.1029/2004GL021269.<br />
#Mlynczak, M. G., et al. (2010), Observations of infrared radiative cooling in the thermosphere on daily to multiyear timescales from the TIMED/SABER instrument, J. Geophys Res., 115, A03309, doi:10.1029/2009JA014713.<br />
#Qian, L., R. G. Roble, S. C. Solomon, and T. J. Kane (2006), Calculated and observed climate change in the thermosphere, and a prediction for solar cycle 24, Geophys. Res. Lett., 33, L23705, doi:10.1029/2006GL027185.<br />
#Qian, L., S. C. Solomon, R. G. Roble, and T. J. Kane (2008), Model simulations of global change in the ionosphere, Geophys. Res. Lett., 35, L07811, doi:10.1029/2007GL033156.<br />
#Qian, L., A. G. Burns, S. C. Solomon, and R. G. Roble (2009), The effect of carbon dioxide cooling on trends in the F2-layer ionosphere, J. Atmos. Solar-Terr. Phys., 71, 1592–1601.<br />
#Roble, R. G. (1995), Energetics of the mesosphere and thermosphere, The Upper Mesosphere and Lower Thermosphere, Geophys. Monogr. Ser., 87, 1–21.<br />
#Roble, R. G., and R. E. Dickinson (1989), How will changes in carbon dioxide and methane modify the mean structure of the mesosphere and thermosphere?, Geophys. Res. Lett., 16, 1441–1444.<br />
#Solomon, S. C., T. N. Woods, L. V. Didkovsky, J. T. Emmert, and L. Qian (2010), Anomalously low solar extreme-ultraviolet irradiance and thermospheric density during solar minimum, Geophys. Res. Lett., 37, L16103, doi:10.1029/2010GL044468. <br />
#Solomon, S. C., L. Qian, L. V. Didkovsky, R. A. Viereck, and T. N. Woods (2011), Causes of low thermospheric density during the 2007–2009 solar minimum, J. Geophys. Res., 116, A00H07, doi:10.1029/2011JA016508.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-04-18T17:03:53Z<p>Marsh: /* Upcoming Meetings */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
Second CAWSES-2 Task 2 Workshop: '''Modeling Polar Mesospheric Cloud Trends''', May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
CEDAR 2012 Workshop session on ''' Thermosphere and Ionosphere Climate'''<br />
[http://cedarweb.hao.ucar.edu/wiki/index.php/2012_Workshop:Thermosphere_and_Ionosphere_Climate]<br />
24-29 June 2012, Santa Fe, New Mexico, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on''' Long-Term Changes and Trends in the Atmosphere''', which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-04-13T22:40:00Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere, which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_composition.Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.2012-04-13T22:38:06Z<p>Marsh: moved Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition. to Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition:&#3</p>
<hr />
<div>#REDIRECT [[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition]]</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2012-04-13T22:38:06Z<p>Marsh: moved Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition. to Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition:&#3</p>
<hr />
<div>* Project leaders: G.Thomas (USA), U.Berger (Germany)<br />
* Project members: S. Bailey (USA),G. Baumgarten(Germany),M. DeLand (USA), J. Fiedler (Germany),B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), F.-J. Lübken (Gemany), A. Merkel (USA), N. Pertsev (Russia), J. Russell III (USA), E. Shettle (USA)<br />
==Introduction==<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year time series of SBUV (Solar Backscatter Ultraviolet) satellite measurements (see Figure 1). SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable. It is important to understand the relative roles of these three factors (solar, inter-annual and long-term forcing) before a definitive long-term trend can be evaluated. Furthermore the problem of attribution, that is, the nature of the various forcings on ice formation is not yet understood. For example with respect to the long-term changes, is a lowered temperature due to higher carbon dioxide responsible for the observed increase in brightness and occurrence frequency of MC? Or are water vapor changes due to oxidation of methane responsible, since we know that lower atmospheric methane has more than doubled over the past 120 years, and methane oxidation leads to upper atmospheric water vapor. The failure to detect any changes in the altitude of MC since the first measurement made by Otto Jesse in the late nineteenth century has provided an important constraint, since water vapor changes and temperature changes affect cloud altitude in different ways. Fortunately, the state of the art in modeling has now reached a point where ice formation is coupled with general circulation models. In a recent study Berger and Lübken (2011) showed that in the summer period 1979 -1997 at mid-latitudes strong cooling of up to 3-4 K/decade occurs in the middle mesosphere, in the period 1961-1979 the middle atmosphere cooled significantly less, and for the period 1997-2009 they find a warming of ~1 K/decade. For the first time, modeled temperature trends confirm the extraordinarily large temperature trends observed at mid-latitudes during the period 1979-1997 derived from lidar measurements, satellite data, and phase height measurements. The differences in temperature trends in the mesosphere originate from the evolution of stratospheric ozone in the past 50 years, e.g. the observed reversal of both stratospheric and mesospheric temperature trends in the mid 1990s is caused by the recovery of <br />
stratospheric ozone (WMO report 2011). Therefore a new research question arises: does any trend in MC show a similar behavior? Relevant publications on this subject are reported in the references below:<br />
[[File:Vqn-fig2rev.png|thumb|Fig. 1 A comparison of the seasonal PMC frequency of occurrence measured by SBUV and the fit to a linear regression in time and solar activity (upper panel) by latitude band and (lower panel) for all latitude bands combined between 54°N and 82°N. The error bars are the confidence limits in the individual seasonal mean values based on counting statistics, which do not reflect other factors such as inter-annual variability in large scale dynamics (from Reference 5)]]<br />
<br />
==References==<br />
<br />
#Luebken, F.-J., U. Berger, and G. Baumgarten (2009), Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds, J. Geophys. Res., 114, D00I06, doi:10.1029/2009JD012377 <br />
#Merkel, A. W., Marsh, D. R., Gettelman, A., and Jensen, E. J.: On the relationship of polar mesospheric cloud ice water content, particle radius and mesospheric temperature and its use in multi-dimensional models, Atmos. Chem. Phys., 9, 8889-8901, 2009<br />
# Merkel, A. W., D. Marsh, G. E. Thomas, C. Bardeen, M. Deland, WACCM simulations of long-term changes in polar mesospheric clouds, Layered Phenomenon in Mesospheric Regions (LPMR) Conference, Stockholm, 2009<br />
#Marsh, D and A. W. Merkel, 30-year PMC variability modeled by WACCM, SA33B-08, Fall AGU Meeting, San Francisco, 2009<br />
#Shettle,E. P.,M. T. DeLand, G. E. Thomas, and J. J. Olivero (2009), Long term variations in the frequency of polar mesospheric clouds in the Northern Hemisphere from SBUV, Geophys. Res. Lett., 36, L02803, doi:10.1029/2008GL036048.<br />
#Thomas, G. E., D. Marsh and F.-J. Lübken, Mesospheric ice clouds as indicators of upper atmosphere climate change, EOS, Transactions, American Geophysical Union, 91, No. 20, 18 May 2010, p. 183.<br />
#Berger, U., and F.-J. Lübken (2011), Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., 38, L22804, doi: 10.1029/2011GL049528.<br />
#WMO (2011), Global ozone research and monitoring project-Report no. 52, Scientific assessment of ozone depletion: 2010, World Meteorological Organization<br />
<br />
<br />
=Workshops and Meetings=<br />
The first workshop under the auspices of this working group was held in Boulder, Colorado on December 10 & 11, 2010, entitled Modeling Trends in mesospheric clouds (Thomas et al, 2010).<br />
[[file:COSTEP_LOGO_240.gif|left|]]<br />
==[[Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012]]==<br />
<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, USA.<br />
<br />
We announce here a forthcoming workshop to be held in Boulder, CO USA on May 3-4, 2012. This is the 7th workshop sponsored by IAGA/ICMA/CAWSES and focusses on global change in the upper mesosphere, specifically decadal-scale trends in Polar Mesospheric Clouds, PMC (or Noctilucent Clouds, NLC, as they are traditionally called when observed from the ground at twilight).<br />
<br />
The issue of long-term changes in PMC was addressed in the first workshop in Boulder, Colorado, 10-11 December, 2009 (Thomas et al, 2010). A long suite of satellite measurements by the Solar Backscatter Ultraviolet Spectrometer (SBUV) dating back to 1979 shows a significant long-term trend in mesospheric cloud activity and brightness. Attribution of trends in these high-altitude ice clouds (~83 km) includes: (1) increasing carbon dioxide concentrations which tend to cool the upper mesosphere (the 80-90 km 'mesopause region'); (2) increasing water vapor due to growing concentrations of methane, in addition to changing efficiency of tropospheric water vapor entry through the tropopause; (3) shrinking of the upper atmosphere arising largely from decreased ozone levels and subsequent stratospheric cooling; (4) increased concentrations of water vapor due to the rise in space traffic over the last 30 years. Other possible causes are long-term changes in winds and wind filtering of gravity waves which dominate the dynamics of the high-latitude summertime mesopause region. An even larger (cyclic) trend is superimposed on the long-term record, believed to be a result of the solar cycle, but not well understood.<br />
<br />
General circulation models coupled with ice formation are now capable of simulating the SBUV trends to a remarkable degree, as discussed in the first workshop. However, new modeling results have brought out the importance of ozone trends, which affect the heat balance of the entire upper atmosphere. The LIMA/ICE model predicts a 'break-point' in the time series of PMC trends, due to the turn-around of the ozone trend in the mid-1990's. A wealth of new data from several satellite missions (AIM, ODIN, TIMED) are available. The Aeronomy of Ice in the Mesosphere (AIM) directly addresses the processes which control ice cloud evolution. In addition, more information is now available on diurnal variations in ice water content, which in principle affects the analysis of trends made from satellites in sun-synchronous orbits with slowly-varying local time coverage. These and other advances in modeling, data availability and trend analysis are motivations for a coming together of both modelers and data analysts to assess the current state of knowledge. A goal of the workshop would be to make recommendations for future work to resolve many of the outstanding issues.<br />
<br />
The PMC Trend Workshop will be held at the Laboratory for Atmospheric Physics, University of Colorado, Boulder, Co, USA on May 3 and 4, 2012. All interested researchers, and particularly students, are invited to the meeting. Our current plans are that no registration fees will be charged. We have now committed the travel funds allocated to us by CAWSES.<br />
<br />
Gary Thomas (thomas@lasp.colorado.edu) and Uwe Berger (berger@iap-kborn.de), co-chairs of CAWSES-II, Task 2, Project 3<br />
<br />
===Registration===<br />
<br />
Please go to https://www2.acd.ucar.edu/cawses/registration so that you may now register, and record your preferences for food, etc. This will only take a minute of your time, but is very important, so that we will know the attendance and how much food to order. '''The deadline for registration is APRIL 26'''. <br />
<br />
===MEETING AGENDA===<br />
<br />
==AM Thursday, May 3== <br />
<br />
0830-0840: Gary Thomas, LASP<br />
Welcome & Summary of Workshop Objectives<br />
<br />
====[[Long-term Trends: PMC Observations]]====<br />
0840-0900<br />
John Olivero, Embry-Riddle University, USA, Some Historical Notes on Noctilucent Cloud Studies<br />
<br />
0900-0910 Q&A, and discussion<br />
<br />
0910-0930 Matthew DeLand, SSAI, USA,Current PMC Trends Derived from SBUV Measurements<br />
<br />
0930-0940 Q&A, and discussion<br />
<br />
0940-1000 Mark Zalcik, Coordinator, NLC Can Am Network, Canada,Two Decades of Noctilucent Cloud Monitoring in North America<br />
<br />
1000-1010 Q&A, and discussion<br />
<br />
1010-1025 P. Dalin, Swedish Institute of Space Physics, Sweden,On the long-term trends in noctilucent clouds as observed from the ground and on the trends in the OH summer temperature as measured in Moscow and Lithuania<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
1100-1120 Gerd Baumgarten, IUP, Germany,Decadal observations of particle sizes and water vapor content of NLC<br />
<br />
1120-1130 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Temperature & Water Vapor Observations]]====<br />
<br />
1130-1150 Alain Hauchecorne, Laboratoire ATmosphères, France, Temperature trends in the stratosphere and in the mesosphere as seen from Rayleigh lidar observations<br />
<br />
1150-1200 Q&A, and discussion<br />
<br />
1200-1220 Karen Rosenlof, NOAA, USA , A new satellite based zonally averaged time series of stratospheric water vapor<br />
<br />
1220-1230 Q&A, and discussion<br />
<br />
1230-1330 Lunch Break<br />
<br />
==PM Thursday, May 3==<br />
<br />
====[[ Long-term Trends: Temperature & Water Vapor Observations (cont.)]]====<br />
<br />
1330-1350 Gerald Nedoluha, NRL, USA , Long-Term Ground-based Microwave Measurements of Middle Atmospheric Water Vapor from NDACC sites<br />
<br />
1350-1400 Q&A, and discussion<br />
<br />
1400-1420 Michael Stevens, NRL, USA ,The impact of space shuttle main engine exhaust on PMCs and implications to trend studies<br />
<br />
1420-1430 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Modeling]]====<br />
<br />
1430-1450 Uwe Berger, IUP, Germany,Solar variability and trend effects in mesospheric ice layers<br />
<br />
1450-1500 Q&A, and discussion<br />
<br />
1500-1520 Aimee Merkel, LASP, USA,WACCM-PMC simulations of long-term trends of PMC<br />
<br />
1520-1530 Q&A, and discussion<br />
<br />
1530-1600 Coffee Break<br />
<br />
1600-1620 David Siskind, NRL, USA,The PMC region as an integrator of coupling processes: Implications for trend studies from AIM and other missions<br />
<br />
1620-1630 Q&A, and discussion<br />
<br />
1630-1650 Stan Solomon, NCAR, USA,Thermospheric Temperature Trends: Modeling and Observations<br />
<br />
1650-1700 Q&A and discussion<br />
<br />
1700-1720 Dan Marsh, NCAR, USA,Climate change in the mesosphere from 1850 to 2100 in CESM-WACCM<br />
<br />
1720-1730 Q&A, and discussion<br />
<br />
1730-1750 Kota Okamoto, The University of Tokyo, Japan, On the dynamical responses in the middle atmosphere to ozone recovery and CO2 increase<br />
<br />
1750-1800 Q&A, and discussion<br />
<br />
1800 Adjourn<br />
<br />
1900-2100 Group Dinner (TBD)<br />
<br />
==AM Friday, Friday, May 4==<br />
<br />
====[[Inter-annual, hemispheric and seasonal variability: Observations]]====<br />
<br />
0830-0850 James Russell III, Hampton Univ, USA, AIM science results and their significance for PMC long-term change studies<br />
<br />
0850-0900 Q&A, and discussion <br />
<br />
0900-0920 Cora Randall, LASP, USA, AIM/CIPS Observations of PMC Variability<br />
<br />
0920-0930 Q&A, and discussion<br />
<br />
0930-0945 Rachel Ward, Utah State University, USA, Comparison of Northern and Southern Hemisphere Mesospheric Gravity Waves using CIPS PMC Data<br />
<br />
0945-0950 Q&A, and discussion<br />
<br />
0950-1005 Susanne Benze, LASP, USA, On the onset of polar mesospheric cloud seasons<br />
<br />
1005-1010 Q&A, and discussion<br />
<br />
1010-1025 Jia Yue, NCAR, USA ,Fast meridional transport in the lower thermosphere by planetary-scale waves<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1050 Coffee Break<br />
<br />
====[[Properties of PMC and their Environment: Observations]]====<br />
<br />
1050-1105 E.J. Llewellyn, University of Saskatchewan, Canada, Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb<br />
<br />
1105-1110 Q&A, and discussion<br />
<br />
1110-1125 Richard Goldberg, GSFC, USA, Study of an IR limb emission anomaly observed by SABER/TIMED in the mesosphere-lower thermosphere (MLT) region<br />
<br />
1125-1130 Q&A, and discussion<br />
<br />
1130-1145 Scott Robertson, U of Colorado, USA, Detection of Meteoric Dust in Mesosphere by the CHAMPS Rockets<br />
<br />
1145-1150 Q&A, and discussion<br />
<br />
1150-1205 Kristell Pérot, LATMOS Laboratoire ATmosphères, France, PMC Particle Size Retrieval from GOMOS / ENVISAT Observations<br />
<br />
1205-1210 Q&A and discussion<br />
<br />
1210-1310 Lunch<br />
<br />
==PM Friday, Friday, May 4==<br />
<br />
====[[Properties of PMC and their Environment: Modeling]]====<br />
<br />
1310-1330 Charles Bardeen, NCAR, USA, Simulations of PMC during the AIM time period using WACCM/CARMA<br />
<br />
1330-1340 Q&A, and discussion<br />
<br />
1340-1355 Mark Hervig, GATS, Inc., USA, The Smoke Content of Ice: Interpretation of SOFIE Results<br />
<br />
1355-1400 Q&A, and discussion<br />
<br />
1400-1415 Mark Hervig, GATS, Inc., USA, The 0D Model of PMC: Comparisons with AIM SOFIE data<br />
<br />
1415-1425 Q&A, and discussion<br />
<br />
1425-1440 I. Azeem, Astraspace, USA, Simulations of Shuttle Main Engine Plume Effects on Lower Thermosphere Energetics and Chemistry<br />
<br />
1440-1445 Q&A, and discussion<br />
<br />
1445-1545 Panel and group discussion<br />
<br />
1545-1630 Concluding remarks & summary from the project co-chairs<br />
<br />
1630 Adjourn<br />
<br />
==Local Organizing Committee: Aimee.Merkel@lasp.colorado.edu,Dan Marsh (marsh@ucar.edu) and Charles Bardeen (bardeenc@ucar.edu)==<br />
<br />
===NOTE: The Particle Size Workshop,originally scheduled for May 2, has been postponed to a later date.===<br />
<br />
==SPECIAL JOURNAL ISSUE ON UPPER ATMOSPHERIC TRENDS NOW AVAILABLE. The joint JGR/Space, JGR/Atmospheres special section on upper atmospheric trends is now complete, and can be accessed at http://www.agu.org/journals/ja/special_sections.shtml?collectionCode=UATREND1&amp;journalCode=JA==<br />
<br />
='''Observing Facilities'''=<br />
<br />
<br />
== Aeronomy of Ice in the Mesosphere (AIM), a NASA satellite mission (2007-) ==<br />
[[File:AIMforWIKI.png|left|Fig. 2 Artist's conception of the AIM spacecraft in orbit, showing the line of sight of the SOFIE solar occultation experiment (courtesy, J. Russell III]][[File:CIPSfig1.png|right|]]AIM was launched from Vandenberg Air Force Base on April 25, 2007 becoming the first satellite mission dedicated to the study of Polar Mesospheric Clouds (PMCs). A Pegasus XL rocket placed the AIM satellite into a near circular (601 km apogee, 595 km perigee), 12:00 AM/PM sun-synchronous orbit. By measuring PMCs and the thermal, chemical and dynamical environment in which they form, AIM will quantify the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of long-term variability in mesospheric climate and its relationship to global change. The results of AIM will be a rigorous test and validation of predictive models that then can reliably use past PMC changes and current data to assess trends as indicators of global change. This goal is being achieved by measuring PMC densities, spatial distribution, particle size distributions, gravity wave activity, meteoric smoke influx to the atmosphere and vertical profiles of temperature, H2O, O3, CH4, NO, and CO2. <br />
<br />
The overall goal of AIM is to resolve why PMCs form and why they vary. It has been suggested that the observed changes in the clouds are related to increased concentrations of greenhouse gases. This suggestion is plausible because an increase in carbon dioxide, while warming the surface of the Earth, cools the upper atmosphere which can facilitate mesospheric cloud formation there. Additionally, increases in methane at the surface of the Earth lead to increases in water vapor at high altitudes through chemical oxidation processes, which further facilitates cloud formation and growth. While plausible, this greenhouse gas hypothesis has not yet been proven.The AIM webpage is at [http://aim.hamptonu.edu/]<br />
<br />
<br />
----<br />
<br />
== Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) ==<br />
[[File:alomar-rmr-lidar-small.png|left|Fig. 1:ALOMAR observatory and laser beams of the ALOMAR RMR-lidar during operation with tilted telescopes (courtesy, J. Fiedler)]] [[File:rmr-timeseries-small.png|right|]]Fig. 2:Year-to-year variability of seasonal mean NLC occurrence and altitude for two different cloud classes. The blue curves contain all measurements having a sensitivity above the long-term detection limit, whereas the green curves show results for strong clouds only. The vertical bars indicate 95% confidence limits for the occurrence and errors of the mean altitudes. For more information see text and references.<br />
The Rayleigh/Mie/Raman (RMR) lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) is located on top of a ≈400 m high mountain in Northern Norway (69.3°N, 16.0°E). It was installed in 1994 and designed for multi-parameter investigations of the Arctic middle atmosphere on a climatological basis. Because of its Arctic location, the lidar is optimized for measurements during full sunlight. Appropriate technical solutions, laser wavelength stabilization in combination with strong spectral as well as spatial filtering at the receiving system, have been implemented. The lidar is a complex twin-system consisting of two power lasers, two receiving telescopes, and one optical bench for spectral separation and filtering of the light received from the atmosphere. The lasers emit pulses at three wavelengths (355 nm, 532 nm, 1064 nm) simultaneously with an overall peak power of 150 MW per laser. The backscattered light from the atmosphere is collected by telescopes with a diameter of 1.8 m each. They can be tilted up to 30° off-zenith to allow different viewing directions (Fig. 1), which separates the sounding volume up to 90 km at an altitude of 80 km. After spectral and intensity separation the light is analyzed by 15 channels and recorded by single photon counting detectors. <br />
One main objective of the RMR-lidar is the observation of ice layers in the mesopause region, which are known as noctilucent clouds (NLC) and polar mesospheric clouds (PMC). Throughout the NLC season (1 June to 15 August) the lidar is operational for 24 hours per day to measure whenever permitted by the local weather conditions. This yielded a total of more than 4000 measurement hours from 1997 to 2009. NLC were observed during ≈1700 hours which is the largest NLC data base acquired by lidar. The data are used to investigate decadal scale changes of NLC parameters, size and number density of the ice particles, as well as small scale structures which are often observed in the cloud layers. Fig. 2 shows the time series of NLC occurrence and altitude above ALOMAR covering one solar cycle (taken from reference 2). During these 11 years there is no statistical significant anti-correlation between cloud occurrence and solar activity, which is partly in contrast to other data sets. The mean cloud altitude is 83.2 km and appears to remain nearly unchanged since the first NLC observations more than 100 years ago.<br />
----<br />
<br />
==Visual Observations of Noctilucent Clouds ==<br />
<br />
<br />
<br />
[[File:2005-06-24_213509-GB-2005-06-24_213551-GB-sm.png|center|Fig. 1:Noctilucent cloud display seen from Kühlungsborn, Germany, on June 24, 2005 while the sun is about 8 degrees below the horizon. (courtesy, G. Baumgarten)]] Scientific interest in noctilucent clouds (NLC) can be traced back to 1884 when many observers watched the twilight sky to see the dramatic sunsets caused by dust from Krakatoa, which had erupted during the previous year. Captivating displays of 'night shining' clouds, were seen and quickly recognized as lying at much higher altitude than normal clouds. For much of the 20th century, visual and photographic observations were the only methods available for systematic monitoring of NLC characteristics. By the early 1960's it was clear that their occurrence rates varied enormously from year to year. Widespread, intense displays of NLC were seen for a few consecutive summers, with NLC reported from somewhere around the 50 - 60 N latitude band almost every night over the summer season. These periods were followed by years when almost no NLC at all were seen. The most notable 'high spots' for NLC were the years 1885-1890 and 1963-1968, which were each followed by strong declines in NLC reports even though the same observers as during the 'hot spots' continued to look for them (reference 1).<br />
<br />
Starting with the International Geophysical Year in 1958, professionally organized observing networks started to gather systematic records of visual sightings of noctilucent clouds (see references). Even though professional involvement has generally ended, or become sporadic, systematic NLC observations are still collected by networks of enthusiasts, in Europe, Russia, Canada and North America. Since 1996, visual observations by members of the public are collected at a number of regional or national centers [http://www.kersland.plus.com/nlcrepor.htm#nlccanam], and since 1996 at the 'Noctilucent Cloud Observers Homepage' [ http://www.kersland.plus.com/]. NLC observations from the UK and Denmark since 1964 form the longest continuous record (observing latitudes from 51 - 61 N). These show how NLC are most common in years of low solar activity, and rare in years of high solar activity. They do not show any significant increase over the last 45 years although a few percent increase (or decrease) cannot be ruled out (Fig. 2, reference 3).<br />
[[File:NLC_UK_Denmark.png|200px|thumb|right|Fig. 2 A comparison of solar activity and the seasonal NLC frequency of occurrence according to reports of visual observations from the UK and Denmark (from Reference 3, extended to 2009 using internet reports [http://www.kersland.plus.com/]) ]]<br />
<br />
Although monitoring of large-scale structures and possible trends in NLC is being taken over by satellite measurements, visual and photographic observations still have an important role to play. For example, they are the best method available for studying fine-scale structure, on scales of 10s of km or less, and they can be instrumental in identifying NLC at unusually low latitudes where satellites observations and ground-based remote sensing instruments are not available. <br />
<br />
[[File:2005-06-24_213509-GB-sm.jpg|left|Fig. 3:Wave structures on scales of several km are often seen in noctilucent cloud and highlight the dynamical processes leading to the cold summer mesopause. (courtesy, G. Baumgarten)]] <br />
<br />
#Fogle,B.and B.Haurwitz,Long term variations in noctilucent cloud activity and their possible cause, in Climatological Research,edited by K.Fraedrich, M.Hantel,H.Claussen Korff,and E.Ruprecht,pp. 263–276,Heft 7,Bonner Meteorologische Abhandlungen.,Bonn,Germany,1974. <br />
#Romejko, V.A., P.A. Dalin, N.N. Pertsev, Forty years of Noctilucent Clouds observations near Moscow: database and simple statistics, J. Geophys. Res., 108, D8, 8443, doi: 10.1029/2002JD002364, 2003.<br />
#Kirkwood, S., P. Dalin, A. Rechou, Noctilucent clouds observed from the UK and Denmark – trends and variations over 43 years, Annales Geophysicae, 26, 1243-1254, 2008.<br />
----<br />
<br />
<br />
<br />
== Additional notes about NLC long-term behavior according to visual observations ==<br />
<br />
<br />
1. There is no distinct contradiction when comparing a trend in the NLC occurrence frequency from ground-based observations and a trend in the PMC satellite observations for lower latitudes (50-64°N), if we take the same years for an analysis. The difference between the NLC and PMC trend is rather in their significance probability. However, if we consider ground-based NLC observations for more than 40 years (which are longer than space-borne measurements) we arrive at almost zero trend in the NLC occurrence frequency and at very small positive trend in the NLC brightness which have no statistical significance.<br />
<br />
[[File:Pertsevfig_1.png|200px|thumb|right|Fig. 1 Residuals (after subtracting the variation correlated with the solar Lyman alpha flux) of the normalized NLC frequency. The thick line represents the secular trend and its 95% confidence interval. The upper panel demonstrates the Moscow linear fit for 1962–2005, the central panel is for the Moscow linear fit for 1983–2005 and the lower panel is for the Danish data for 1983–2005 (courtesy N. N. Pertsev).]]<br />
<br />
2. NLC most frequently occur in 1-2 years after the sunspot minimum and this delay is statistically significant. The PMC observations show a smaller delay of 0.5±0.5 year.<br />
<br />
3. Concerning the year of the NLC discovery, we should note the following. The majority of papers, devoted to first observations of noctilucent clouds, refer not to 1884 but to 1885 as a year of first reliable descriptions undoubtedly concerning noctilucent clouds. Leslie (1884) did describe some sky phenomenon, resembling noctilucent clouds, but in his successive papers, Leslie (1885) and (1886), devoted to luminous clouds as a new phenomenon, he wrote nothing about priority of that observation of 1884; moreover, he did not refer to it at all. So, the description of Leslie's observation of 1884 cannot be regarded as reliable. Summarizing, Gadsden and Schröder (1989) wrote in their canonical book: “…It is certain that at the times of coloured twilight appearances of 1883/1884, no noctilucent clouds were discovered. Various reports also exist which could be interpreted as noctilucent clouds, but this will always remain uncertain (Pernter 1889; Schröder 1975; Gadsden 1985).”. <br />
<br />
References:<br />
<br />
#Dalin, P., S. Kirkwood, H. Andersen, O. Hansen, N. Pertsev, V. Romejko, Comparison of long-term Moscow and Danish NLC observations: statistical results, Annales Geophysicae, 24, 2841-2849, 2006.<br />
#Leslie, R., 1884. The sky-glows. Nature 30, 583.<br />
#Leslie, R., 1885. Sky glows. Nature 32, 245.<br />
#Leslie, R., 1886. Luminous clouds. Nature 34, 264.<br />
<br />
P. Dalin, N. Pertsev</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2012-04-12T23:53:08Z<p>Marsh: /* Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012 */</p>
<hr />
<div>* Project leaders: G.Thomas (USA), U.Berger (Germany)<br />
* Project members: S. Bailey (USA),G. Baumgarten(Germany),M. DeLand (USA), J. Fiedler (Germany),B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), F.-J. Lübken (Gemany), A. Merkel (USA), N. Pertsev (Russia), J. Russell III (USA), E. Shettle (USA)<br />
==Introduction==<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year time series of SBUV (Solar Backscatter Ultraviolet) satellite measurements (see Figure 1). SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable. It is important to understand the relative roles of these three factors (solar, inter-annual and long-term forcing) before a definitive long-term trend can be evaluated. Furthermore the problem of attribution, that is, the nature of the various forcings on ice formation is not yet understood. For example with respect to the long-term changes, is a lowered temperature due to higher carbon dioxide responsible for the observed increase in brightness and occurrence frequency of MC? Or are water vapor changes due to oxidation of methane responsible, since we know that lower atmospheric methane has more than doubled over the past 120 years, and methane oxidation leads to upper atmospheric water vapor. The failure to detect any changes in the altitude of MC since the first measurement made by Otto Jesse in the late nineteenth century has provided an important constraint, since water vapor changes and temperature changes affect cloud altitude in different ways. Fortunately, the state of the art in modeling has now reached a point where ice formation is coupled with general circulation models. In a recent study Berger and Lübken (2011) showed that in the summer period 1979 -1997 at mid-latitudes strong cooling of up to 3-4 K/decade occurs in the middle mesosphere, in the period 1961-1979 the middle atmosphere cooled significantly less, and for the period 1997-2009 they find a warming of ~1 K/decade. For the first time, modeled temperature trends confirm the extraordinarily large temperature trends observed at mid-latitudes during the period 1979-1997 derived from lidar measurements, satellite data, and phase height measurements. The differences in temperature trends in the mesosphere originate from the evolution of stratospheric ozone in the past 50 years, e.g. the observed reversal of both stratospheric and mesospheric temperature trends in the mid 1990s is caused by the recovery of <br />
stratospheric ozone (WMO report 2011). Therefore a new research question arises: does any trend in MC show a similar behavior? Relevant publications on this subject are reported in the references below:<br />
[[File:Vqn-fig2rev.png|thumb|Fig. 1 A comparison of the seasonal PMC frequency of occurrence measured by SBUV and the fit to a linear regression in time and solar activity (upper panel) by latitude band and (lower panel) for all latitude bands combined between 54°N and 82°N. The error bars are the confidence limits in the individual seasonal mean values based on counting statistics, which do not reflect other factors such as inter-annual variability in large scale dynamics (from Reference 5)]]<br />
<br />
==References==<br />
<br />
#Luebken, F.-J., U. Berger, and G. Baumgarten (2009), Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds, J. Geophys. Res., 114, D00I06, doi:10.1029/2009JD012377 <br />
#Merkel, A. W., Marsh, D. R., Gettelman, A., and Jensen, E. J.: On the relationship of polar mesospheric cloud ice water content, particle radius and mesospheric temperature and its use in multi-dimensional models, Atmos. Chem. Phys., 9, 8889-8901, 2009<br />
# Merkel, A. W., D. Marsh, G. E. Thomas, C. Bardeen, M. Deland, WACCM simulations of long-term changes in polar mesospheric clouds, Layered Phenomenon in Mesospheric Regions (LPMR) Conference, Stockholm, 2009<br />
#Marsh, D and A. W. Merkel, 30-year PMC variability modeled by WACCM, SA33B-08, Fall AGU Meeting, San Francisco, 2009<br />
#Shettle,E. P.,M. T. DeLand, G. E. Thomas, and J. J. Olivero (2009), Long term variations in the frequency of polar mesospheric clouds in the Northern Hemisphere from SBUV, Geophys. Res. Lett., 36, L02803, doi:10.1029/2008GL036048.<br />
#Thomas, G. E., D. Marsh and F.-J. Lübken, Mesospheric ice clouds as indicators of upper atmosphere climate change, EOS, Transactions, American Geophysical Union, 91, No. 20, 18 May 2010, p. 183.<br />
#Berger, U., and F.-J. Lübken (2011), Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., 38, L22804, doi: 10.1029/2011GL049528.<br />
#WMO (2011), Global ozone research and monitoring project-Report no. 52, Scientific assessment of ozone depletion: 2010, World Meteorological Organization<br />
<br />
<br />
=Workshops and Meetings=<br />
The first workshop under the auspices of this working group was held in Boulder, Colorado on December 10 & 11, 2010, entitled Modeling Trends in mesospheric clouds (Thomas et al, 2010).<br />
[[file:COSTEP_LOGO_240.gif|left|]]<br />
==[[Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012]]==<br />
<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, USA.<br />
<br />
We announce here a forthcoming workshop to be held in Boulder, CO USA on May 3-4, 2012. This is the 7th workshop sponsored by IAGA/ICMA/CAWSES and focusses on global change in the upper mesosphere, specifically decadal-scale trends in Polar Mesospheric Clouds, PMC (or Noctilucent Clouds, NLC, as they are traditionally called when observed from the ground at twilight).<br />
<br />
The issue of long-term changes in PMC was addressed in the first workshop in Boulder, Colorado, 10-11 December, 2009 (Thomas et al, 2010). A long suite of satellite measurements by the Solar Backscatter Ultraviolet Spectrometer (SBUV) dating back to 1979 shows a significant long-term trend in mesospheric cloud activity and brightness. Attribution of trends in these high-altitude ice clouds (~83 km) includes: (1) increasing carbon dioxide concentrations which tend to cool the upper mesosphere (the 80-90 km 'mesopause region'); (2) increasing water vapor due to growing concentrations of methane, in addition to changing efficiency of tropospheric water vapor entry through the tropopause; (3) shrinking of the upper atmosphere arising largely from decreased ozone levels and subsequent stratospheric cooling; (4) increased concentrations of water vapor due to the rise in space traffic over the last 30 years. Other possible causes are long-term changes in winds and wind filtering of gravity waves which dominate the dynamics of the high-latitude summertime mesopause region. An even larger (cyclic) trend is superimposed on the long-term record, believed to be a result of the solar cycle, but not well understood.<br />
<br />
General circulation models coupled with ice formation are now capable of simulating the SBUV trends to a remarkable degree, as discussed in the first workshop. However, new modeling results have brought out the importance of ozone trends, which affect the heat balance of the entire upper atmosphere. The LIMA/ICE model predicts a 'break-point' in the time series of PMC trends, due to the turn-around of the ozone trend in the mid-1990's. A wealth of new data from several satellite missions (AIM, ODIN, TIMED) are available. The Aeronomy of Ice in the Mesosphere (AIM) directly addresses the processes which control ice cloud evolution. In addition, more information is now available on diurnal variations in ice water content, which in principle affects the analysis of trends made from satellites in sun-synchronous orbits with slowly-varying local time coverage. These and other advances in modeling, data availability and trend analysis are motivations for a coming together of both modelers and data analysts to assess the current state of knowledge. A goal of the workshop would be to make recommendations for future work to resolve many of the outstanding issues.<br />
<br />
The PMC Trend Workshop will be held at the Laboratory for Atmospheric Physics, University of Colorado, Boulder, Co, USA on May 3 and 4, 2012. All interested researchers, and particularly students, are invited to the meeting. Our current plans are that no registration fees will be charged. We have now committed the travel funds allocated to us by CAWSES.<br />
<br />
Gary Thomas (thomas@lasp.colorado.edu) and Uwe Berger (berger@iap-kborn.de), co-chairs of CAWSES-II, Task 2, Project 3<br />
<br />
===Registration===<br />
<br />
Please go to https://www2.acd.ucar.edu/cawses/registration so that you may now register, and record your preferences for food, etc. This will only take a minute of your time, but is very important, so that we will know the attendance and how much food to order. '''The deadline for registration is APRIL 26'''. <br />
<br />
===MEETING AGENDA===<br />
<br />
==AM Thursday, May 3== <br />
<br />
0830-0840: Gary Thomas, LASP<br />
Welcome & Summary of Workshop Objectives<br />
<br />
====[[Long-term Trends: PMC Observations]]====<br />
0840-0900<br />
John Olivero, Embry-Riddle University, USA, Some Historical Notes on Noctilucent Cloud Studies<br />
<br />
0900-0910 Q&A, and discussion<br />
<br />
0910-0930 Matthew DeLand, SSAI, USA,Current PMC Trends Derived from SBUV Measurements<br />
<br />
0930-0940 Q&A, and discussion<br />
<br />
0940-1000 Mark Zalcik, Coordinator, NLC Can Am Network, Canada,Two Decades of Noctilucent Cloud Monitoring in North America<br />
<br />
1000-1010 Q&A, and discussion<br />
<br />
1010-1025 P. Dalin, Swedish Institute of Space Physics, Sweden,On the long-term trends in noctilucent clouds as observed from the ground and on the trends in the OH summer temperature as measured in Moscow and Lithuania<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1100 Coffee Break<br />
<br />
1100-1120 Gerd Baumgarten, IUP, Germany,Decadal observations of particle sizes and water vapor content of NLC<br />
<br />
1120-1130 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Temperature & Water Vapor Observations]]====<br />
<br />
1130-1150 Alain Hauchecorne, Laboratoire ATmosphères, France, Temperature trends in the stratosphere and in the mesosphere as seen from Rayleigh lidar observations<br />
<br />
1150-1200 Q&A, and discussion<br />
<br />
1200-1220 Karen Rosenlof, NOAA, USA , A new satellite based zonally averaged time series of stratospheric water vapor<br />
<br />
1220-1230 Q&A, and discussion<br />
<br />
1230-1330 Lunch Break<br />
<br />
==PM Thursday, May 3==<br />
<br />
====[[ Long-term Trends: Temperature & Water Vapor Observations (cont.)]]====<br />
<br />
1330-1350 Gerald Nedoluha, NRL, USA , Long-Term Ground-based Microwave Measurements of Middle Atmospheric Water Vapor from NDACC sites<br />
<br />
1350-1400 Q&A, and discussion<br />
<br />
1400-1420 Michael Stevens, NRL, USA ,The impact of space shuttle main engine exhaust on PMCs and implications to trend studies<br />
<br />
1420-1430 Q&A, and discussion<br />
<br />
====[[Long-term Trends: Modeling]]====<br />
<br />
1430-1450 Uwe Berger, IUP, Germany,Solar variability and trend effects in mesospheric ice layers<br />
<br />
1450-1500 Q&A, and discussion<br />
<br />
1500-1520 Aimee Merkel, LASP, USA,WACCM-PMC simulations of long-term trends of PMC<br />
<br />
1520-1530 Q&A, and discussion<br />
<br />
1530-1600 Coffee Break<br />
<br />
1600-1620 David Siskind, NRL, USA,The PMC region as an integrator of coupling processes: Implications for trend studies from AIM and other missions<br />
<br />
1620-1630 Q&A, and discussion<br />
<br />
1630-1650 Stan Solomon, NCAR, USA,Thermospheric Temperature Trends: Modeling and Observations<br />
<br />
1650-1700 Q&A and discussion<br />
<br />
1700-1720 Dan Marsh, NCAR, USA,Climate change in the mesosphere from 1850 to 2100 in CESM-WACCM<br />
<br />
1720-1730 Q&A, and discussion<br />
<br />
1730-1750 Kota Okamoto, The University of Tokyo, Japan, On the dynamical responses in the middle atmosphere to ozone recovery and CO2 increase<br />
<br />
1750-1800 Q&A, and discussion<br />
<br />
1800 Adjourn<br />
<br />
1900-2100 Group Dinner (TBD)<br />
<br />
==AM Friday, Friday, May 4==<br />
<br />
====[[Inter-annual, hemispheric and seasonal variability: Observations]]====<br />
<br />
0830-0850 James Russell III, Hampton Univ, USA, AIM science results and their significance for PMC long-term change studies<br />
<br />
0850-0900 Q&A, and discussion <br />
<br />
0900-0920 Cora Randall, LASP, USA, AIM/CIPS Observations of PMC Variability<br />
<br />
0920-0930 Q&A, and discussion<br />
<br />
0930-0945 Rachel Ward, Utah State University, USA, Comparison of Northern and Southern Hemisphere Mesospheric Gravity Waves using CIPS PMC Data<br />
<br />
0945-0950 Q&A, and discussion<br />
<br />
0950-1005 Susanne Benze, LASP, USA, On the onset of polar mesospheric cloud seasons<br />
<br />
1005-1010 Q&A, and discussion<br />
<br />
1010-1025 Jia Yue, NCAR, USA ,Fast meridional transport in the lower thermosphere by planetary-scale waves<br />
<br />
1025-1030 Q&A, and discussion<br />
<br />
1030-1050 Coffee Break<br />
<br />
====[[Properties of PMC and their Environment: Observations]]====<br />
<br />
1050-1105 E.J. Llewellyn, University of Saskatchewan, Canada, Special Observational Opportunities Offered by PMCs - Nadir Observations in the Limb<br />
<br />
1105-1110 Q&A, and discussion<br />
<br />
1110-1125 Richard Goldberg, GSFC, USA, Study of an IR limb emission anomaly observed by SABER/TIMED in the mesosphere-lower thermosphere (MLT) region<br />
<br />
1125-1130 Q&A, and discussion<br />
<br />
1130-1145 Scott Robertson, U of Colorado, USA, Detection of Meteoric Dust in Mesosphere by the CHAMPS Rockets<br />
<br />
1145-1150 Q&A, and discussion<br />
<br />
1150-1205 Kristell Pérot, LATMOS Laboratoire ATmosphères, France, PMC Particle Size Retrieval from GOMOS / ENVISAT Observations<br />
<br />
1205-1210 Q&A and discussion<br />
<br />
1210-1310 Lunch<br />
<br />
==PM Friday, Friday, May 4==<br />
<br />
====[[Properties of PMC and their Environment: Modeling]]====<br />
<br />
1310-1330 Charles Bardeen, NCAR, USA, Simulations of PMC during the AIM time period using WACCM/CARMA<br />
<br />
1330-1340 Q&A, and discussion<br />
<br />
1340-1355 Mark Hervig, GATS, Inc., USA, The Smoke Content of Ice: Interpretation of SOFIE Results<br />
<br />
1355-1400 Q&A, and discussion<br />
<br />
1400-1415 Mark Hervig, GATS, Inc., USA, The 0D Model of PMC: Comparisons with AIM SOFIE data<br />
<br />
1415-1425 Q&A, and discussion<br />
<br />
1425-1440 I. Azeem, Astraspace, USA, Simulations of Shuttle Main Engine Plume Effects on Lower Thermosphere Energetics and Chemistry<br />
<br />
1440-1445 Q&A, and discussion<br />
<br />
1445-1545 Panel and group discussion<br />
<br />
1545-1630 Concluding remarks & summary from the project co-chairs<br />
<br />
1630 Adjourn<br />
<br />
==Local Organizing Committee: Aimee.Merkel@lasp.colorado.edu,Dan Marsh (marsh@ucar.edu) and Charles Bardeen (bardeenc@ucar.edu)==<br />
<br />
===NOTE: The Particle Size Workshop,originally scheduled for May 2, has been postponed to a later date.===<br />
<br />
==SPECIAL JOURNAL ISSUE ON UPPER ATMOSPHERIC TRENDS NOW AVAILABLE. The joint JGR/Space, JGR/Atmospheres special section on upper atmospheric trends is now complete, and can be accessed at http://www.agu.org/journals/ja/special_sections.shtml?collectionCode=UATREND1&amp;journalCode=JA==<br />
<br />
='''Observing Facilities'''=<br />
<br />
<br />
== Aeronomy of Ice in the Mesosphere (AIM), a NASA satellite mission (2007-) ==<br />
[[File:AIMforWIKI.png|left|Fig. 2 Artist's conception of the AIM spacecraft in orbit, showing the line of sight of the SOFIE solar occultation experiment (courtesy, J. Russell III]][[File:CIPSfig1.png|right|]]AIM was launched from Vandenberg Air Force Base on April 25, 2007 becoming the first satellite mission dedicated to the study of Polar Mesospheric Clouds (PMCs). A Pegasus XL rocket placed the AIM satellite into a near circular (601 km apogee, 595 km perigee), 12:00 AM/PM sun-synchronous orbit. By measuring PMCs and the thermal, chemical and dynamical environment in which they form, AIM will quantify the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of long-term variability in mesospheric climate and its relationship to global change. The results of AIM will be a rigorous test and validation of predictive models that then can reliably use past PMC changes and current data to assess trends as indicators of global change. This goal is being achieved by measuring PMC densities, spatial distribution, particle size distributions, gravity wave activity, meteoric smoke influx to the atmosphere and vertical profiles of temperature, H2O, O3, CH4, NO, and CO2. <br />
<br />
The overall goal of AIM is to resolve why PMCs form and why they vary. It has been suggested that the observed changes in the clouds are related to increased concentrations of greenhouse gases. This suggestion is plausible because an increase in carbon dioxide, while warming the surface of the Earth, cools the upper atmosphere which can facilitate mesospheric cloud formation there. Additionally, increases in methane at the surface of the Earth lead to increases in water vapor at high altitudes through chemical oxidation processes, which further facilitates cloud formation and growth. While plausible, this greenhouse gas hypothesis has not yet been proven.The AIM webpage is at [http://aim.hamptonu.edu/]<br />
<br />
<br />
----<br />
<br />
== Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) ==<br />
[[File:alomar-rmr-lidar-small.png|left|Fig. 1:ALOMAR observatory and laser beams of the ALOMAR RMR-lidar during operation with tilted telescopes (courtesy, J. Fiedler)]] [[File:rmr-timeseries-small.png|right|]]Fig. 2:Year-to-year variability of seasonal mean NLC occurrence and altitude for two different cloud classes. The blue curves contain all measurements having a sensitivity above the long-term detection limit, whereas the green curves show results for strong clouds only. The vertical bars indicate 95% confidence limits for the occurrence and errors of the mean altitudes. For more information see text and references.<br />
The Rayleigh/Mie/Raman (RMR) lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) is located on top of a ≈400 m high mountain in Northern Norway (69.3°N, 16.0°E). It was installed in 1994 and designed for multi-parameter investigations of the Arctic middle atmosphere on a climatological basis. Because of its Arctic location, the lidar is optimized for measurements during full sunlight. Appropriate technical solutions, laser wavelength stabilization in combination with strong spectral as well as spatial filtering at the receiving system, have been implemented. The lidar is a complex twin-system consisting of two power lasers, two receiving telescopes, and one optical bench for spectral separation and filtering of the light received from the atmosphere. The lasers emit pulses at three wavelengths (355 nm, 532 nm, 1064 nm) simultaneously with an overall peak power of 150 MW per laser. The backscattered light from the atmosphere is collected by telescopes with a diameter of 1.8 m each. They can be tilted up to 30° off-zenith to allow different viewing directions (Fig. 1), which separates the sounding volume up to 90 km at an altitude of 80 km. After spectral and intensity separation the light is analyzed by 15 channels and recorded by single photon counting detectors. <br />
One main objective of the RMR-lidar is the observation of ice layers in the mesopause region, which are known as noctilucent clouds (NLC) and polar mesospheric clouds (PMC). Throughout the NLC season (1 June to 15 August) the lidar is operational for 24 hours per day to measure whenever permitted by the local weather conditions. This yielded a total of more than 4000 measurement hours from 1997 to 2009. NLC were observed during ≈1700 hours which is the largest NLC data base acquired by lidar. The data are used to investigate decadal scale changes of NLC parameters, size and number density of the ice particles, as well as small scale structures which are often observed in the cloud layers. Fig. 2 shows the time series of NLC occurrence and altitude above ALOMAR covering one solar cycle (taken from reference 2). During these 11 years there is no statistical significant anti-correlation between cloud occurrence and solar activity, which is partly in contrast to other data sets. The mean cloud altitude is 83.2 km and appears to remain nearly unchanged since the first NLC observations more than 100 years ago.<br />
----<br />
<br />
==Visual Observations of Noctilucent Clouds ==<br />
<br />
<br />
<br />
[[File:2005-06-24_213509-GB-2005-06-24_213551-GB-sm.png|center|Fig. 1:Noctilucent cloud display seen from Kühlungsborn, Germany, on June 24, 2005 while the sun is about 8 degrees below the horizon. (courtesy, G. Baumgarten)]] Scientific interest in noctilucent clouds (NLC) can be traced back to 1884 when many observers watched the twilight sky to see the dramatic sunsets caused by dust from Krakatoa, which had erupted during the previous year. Captivating displays of 'night shining' clouds, were seen and quickly recognized as lying at much higher altitude than normal clouds. For much of the 20th century, visual and photographic observations were the only methods available for systematic monitoring of NLC characteristics. By the early 1960's it was clear that their occurrence rates varied enormously from year to year. Widespread, intense displays of NLC were seen for a few consecutive summers, with NLC reported from somewhere around the 50 - 60 N latitude band almost every night over the summer season. These periods were followed by years when almost no NLC at all were seen. The most notable 'high spots' for NLC were the years 1885-1890 and 1963-1968, which were each followed by strong declines in NLC reports even though the same observers as during the 'hot spots' continued to look for them (reference 1).<br />
<br />
Starting with the International Geophysical Year in 1958, professionally organized observing networks started to gather systematic records of visual sightings of noctilucent clouds (see references). Even though professional involvement has generally ended, or become sporadic, systematic NLC observations are still collected by networks of enthusiasts, in Europe, Russia, Canada and North America. Since 1996, visual observations by members of the public are collected at a number of regional or national centers [http://www.kersland.plus.com/nlcrepor.htm#nlccanam], and since 1996 at the 'Noctilucent Cloud Observers Homepage' [ http://www.kersland.plus.com/]. NLC observations from the UK and Denmark since 1964 form the longest continuous record (observing latitudes from 51 - 61 N). These show how NLC are most common in years of low solar activity, and rare in years of high solar activity. They do not show any significant increase over the last 45 years although a few percent increase (or decrease) cannot be ruled out (Fig. 2, reference 3).<br />
[[File:NLC_UK_Denmark.png|200px|thumb|right|Fig. 2 A comparison of solar activity and the seasonal NLC frequency of occurrence according to reports of visual observations from the UK and Denmark (from Reference 3, extended to 2009 using internet reports [http://www.kersland.plus.com/]) ]]<br />
<br />
Although monitoring of large-scale structures and possible trends in NLC is being taken over by satellite measurements, visual and photographic observations still have an important role to play. For example, they are the best method available for studying fine-scale structure, on scales of 10s of km or less, and they can be instrumental in identifying NLC at unusually low latitudes where satellites observations and ground-based remote sensing instruments are not available. <br />
<br />
[[File:2005-06-24_213509-GB-sm.jpg|left|Fig. 3:Wave structures on scales of several km are often seen in noctilucent cloud and highlight the dynamical processes leading to the cold summer mesopause. (courtesy, G. Baumgarten)]] <br />
<br />
#Fogle,B.and B.Haurwitz,Long term variations in noctilucent cloud activity and their possible cause, in Climatological Research,edited by K.Fraedrich, M.Hantel,H.Claussen Korff,and E.Ruprecht,pp. 263–276,Heft 7,Bonner Meteorologische Abhandlungen.,Bonn,Germany,1974. <br />
#Romejko, V.A., P.A. Dalin, N.N. Pertsev, Forty years of Noctilucent Clouds observations near Moscow: database and simple statistics, J. Geophys. Res., 108, D8, 8443, doi: 10.1029/2002JD002364, 2003.<br />
#Kirkwood, S., P. Dalin, A. Rechou, Noctilucent clouds observed from the UK and Denmark – trends and variations over 43 years, Annales Geophysicae, 26, 1243-1254, 2008.<br />
----<br />
<br />
<br />
<br />
== Additional notes about NLC long-term behavior according to visual observations ==<br />
<br />
<br />
1. There is no distinct contradiction when comparing a trend in the NLC occurrence frequency from ground-based observations and a trend in the PMC satellite observations for lower latitudes (50-64°N), if we take the same years for an analysis. The difference between the NLC and PMC trend is rather in their significance probability. However, if we consider ground-based NLC observations for more than 40 years (which are longer than space-borne measurements) we arrive at almost zero trend in the NLC occurrence frequency and at very small positive trend in the NLC brightness which have no statistical significance.<br />
<br />
[[File:Pertsevfig_1.png|200px|thumb|right|Fig. 1 Residuals (after subtracting the variation correlated with the solar Lyman alpha flux) of the normalized NLC frequency. The thick line represents the secular trend and its 95% confidence interval. The upper panel demonstrates the Moscow linear fit for 1962–2005, the central panel is for the Moscow linear fit for 1983–2005 and the lower panel is for the Danish data for 1983–2005 (courtesy N. N. Pertsev).]]<br />
<br />
2. NLC most frequently occur in 1-2 years after the sunspot minimum and this delay is statistically significant. The PMC observations show a smaller delay of 0.5±0.5 year.<br />
<br />
3. Concerning the year of the NLC discovery, we should note the following. The majority of papers, devoted to first observations of noctilucent clouds, refer not to 1884 but to 1885 as a year of first reliable descriptions undoubtedly concerning noctilucent clouds. Leslie (1884) did describe some sky phenomenon, resembling noctilucent clouds, but in his successive papers, Leslie (1885) and (1886), devoted to luminous clouds as a new phenomenon, he wrote nothing about priority of that observation of 1884; moreover, he did not refer to it at all. So, the description of Leslie's observation of 1884 cannot be regarded as reliable. Summarizing, Gadsden and Schröder (1989) wrote in their canonical book: “…It is certain that at the times of coloured twilight appearances of 1883/1884, no noctilucent clouds were discovered. Various reports also exist which could be interpreted as noctilucent clouds, but this will always remain uncertain (Pernter 1889; Schröder 1975; Gadsden 1985).”. <br />
<br />
References:<br />
<br />
#Dalin, P., S. Kirkwood, H. Andersen, O. Hansen, N. Pertsev, V. Romejko, Comparison of long-term Moscow and Danish NLC observations: statistical results, Annales Geophysicae, 24, 2841-2849, 2006.<br />
#Leslie, R., 1884. The sky-glows. Nature 30, 583.<br />
#Leslie, R., 1885. Sky glows. Nature 32, 245.<br />
#Leslie, R., 1886. Luminous clouds. Nature 34, 264.<br />
<br />
P. Dalin, N. Pertsev</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22012-02-28T21:58:45Z<p>Marsh: /* Upcoming Meetings */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
Second CAWSES-2 Task 2 Workshop: Modeling Polar Mesospheric Cloud Trends, May 3-4, 2012<br />
Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, USA.<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere, which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22011-11-30T22:13:51Z<p>Marsh: /* Latest publications */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere, which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
A. K. Smith, R. R. Garcia, D. R. Marsh, D. E. Kinnison, and J. H. Richter,<br />
Simulations of the response of mesospheric circulation and temperature to the Antarctic ozone hole,<br />
Geophys. Res. Lett., 37, L22803, doi:10.1029/2010GL045255, 2010[http://www.agu.org/journals/gl/gl0707/2006GL028929/]<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22011-11-30T22:09:34Z<p>Marsh: </p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere, which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Latest publications ==<br />
<br />
U. Berger and F.- J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011[http://www.agu.org/pubs/crossref/2011/2011GL049528.shtml].<br />
<br />
Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
Journal of Geophysical Research, vol. 116, no. , 2011<br />
Guest Editor(s): J. Emmert, G. Beig<br />
[http://www.agu.org/contents/sc/ViewCollection.do?collectionCode=UATREND1&amp;journalCode=JD]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22011-11-30T22:00:31Z<p>Marsh: </p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: J. Bacmeister (US), S. Eckermann (US), M. Ern (DE), P. Kushner (CA), P. Preusse (DE), H. Schmidt (DE), R. A. Vincent (AU), S. Watanabe (JP)<br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: Elisa Manzini (IT), S. Eckermann (US)<br />
* Project members: V. Ratnam (IN), P. Espy (NO), Y. Kawatani (JP), E. Becker (DE), N. Harnik (IL) <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: C. Arras (DE), M.Bittner (DE), K. Höppner (DE), J.Scheer (AR), S.Gurubaran (IN), A. Manson (CA), C. Meek (CA), D.Murphy (AU) J. Lastovicka (CZ), P. Mukhtarov (BG), E. Merzlyakov (RU), D.Pancheva (BG), A. Pogoreltsev (RU)<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), S. Nossal (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Upcoming Meetings ==<br />
<br />
7th IAGA/ICMA/CAWSES Workshop on Long-Term Changes and Trends in the Atmosphere, which will be held in September 2012, in Buenos Aires, Argentina [http://www1.herrera.unt.edu.ar/faceyt/trends2012/]<br />
<br />
== Past Meetings ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Call for papers ==<br />
JGR Special Section Title: “Long-term changes in the stratosphere, mesosphere, thermosphere, and ionosphere”<br />
<br />
Submission acceptance begins 10 Sep 2010<br />
<br />
Submission deadline is 19 Nov 2010<br />
<br />
Guest Editors: John Emmert and Gufran Beig<br />
<br />
Manuscripts are invited for a joint special section of JGR-Space Physics and JGR-Atmospheres on trends in the middle and upper atmosphere and ionosphere. Papers are welcome that apply all types of observational techniques to determine the long-term changes and trends in the stratosphere, mesosphere, thermosphere, and ionosphere, that have occurred in the past and also to determine the processes behind those changes. Also solicited are contributions which consider the availability, quality and acquisition of various data sets which may be exploited for trend studies, and statistical methods for deriving and validating those trends. Interpretation and attribution of observational results depends heavily on theoretical models and numerical simulations of the trends, and papers dealing with these topics are particularly welcome. While the troposphere is not the main focus of the special section, it is clear that it has a major role to play in middle and upper atmosphere trends; papers that demonstrate this relevance are also appropriate.<br />
<br />
Manuscripts can be submitted either to JGR-Space Physics or JGR-Atmospheres, via the GEMS website. If possible, please send tentative titles to john.emmert at nrl.navy.mil (this is not mandatory, but will help with planning). For more information, please visit http://www.hao.ucar.edu/TREND2010/JGRspecialSection.php. <br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.2_Changes_in_filteringProject 1.2 Changes in filtering2010-07-14T08:44:49Z<p>Marsh: </p>
<hr />
<div>* Project leaders: Elisa Manzini (Italy) and Stephen Eckermann (USA)<br />
* Project members: TBD.<br />
<br />
__TOC__ <br />
== Introduction ==<br />
<br />
To reach the upper atmosphere, planetary and gravity waves generated in the lower atmosphere (see [http://www.cawses.org/wiki/index.php/Project_1.1_Changes_in_wave_sources Project 1.1]) must propagate through the intervening wind patterns of the lower and middle atmosphere. As these waves propagate obliquely upwards, background wind and temperature changes refract the waves, such that some are absorbed or reflected while others are transmitted to the upper atmosphere. Through the Charney-Drazin criterion, planetary wave transmission and refraction are heavily impacted by global wind patterns that affect, for example, sudden stratospheric warming (SSW) dynamics, while critical-level filtering of gravity waves by mean winds and planetary waves leads to anisotropic distributions of transmitted momentum flux in the upper atmosphere that drive the large-scale climate and circulation at these altitudes. <br />
<br />
Climate modeling has revealed interesting simulated trends in these and other wave filtering characteristics that affect how these simulated future geospace environments respond to projected climate change. For example, most climate models predict secular increases in the strength of the Brewer-Dobson circulation and in the frequency of SSWs due to climate-induced changes in extratropical planetary-wave and orographic gravity-wave drag caused by an altered mean environment for wave propagation driven by CO<sub>2</sub> increases (Li et al. 2008; McLandress and Shepherd, 2009a, 2009b; Butchart et al., 2010). The CO<sub>2</sub> effects also interact with stratospheric ozone loss and recovery both radiatively (Eyring et al., 2007) and dynamically through a modified Southern Annular Mode that shifts the jet stream and Southern Ocean storm tracks poleward (Gillett and Thompson, 2003; Son et al., 2009), further affecting the propagation environment that controls the morphology of waves transmitted to the upper atmosphere. <br />
<br />
Recent observations show that SSWs, for example, yield deep circulation responses that extend through the mesosphere and lower thermosphere (MLT; Siskind et al. 2007) and deep into the ionosphere (Goncharenko and Zhang, 2008). Modeling and observations both indicate that these MLT and ionospheric responses are driven by SSW-induced changes in both planetary-wave and gravity-wave transmission to high altitudes (Siskind et al., 2010; Pedatella and Forbes, 2010) which affect the local wave-driven climate. Similar wave coupling also communicates QBO-like signals to the tropical upper atmosphere through QBO-modulated wave transmission and filtering (Hagan et al. 1999; Garcia and Sassi, 1999; Wu et al. 2009). How or if the changes in wave filtering characteristics in the lower and middle atmospheres, due to tropospheric CO<sub>2</sub> and stratospheric O<sub>3</sub> trends, can communicate related climate-change-induced responses to the upper atmosphere through wave coupling, remains unclear and largely uninvestigated. This project seeks to foster research and collaborations that cast light on these and related questions.<br />
<br />
== Questions ==<br />
<br />
* Do the robust CO<sub>2</sub>–induced changes in extratropical stratospheric planetary- and gravity-wave drag in GCMs (due to modified filtering and refraction) affect MLT and ionospheric climate through modified upper-atmospheric wave driving?<br />
<br />
* Do the modifications in these simulated features due to stratospheric ozone loss and recovery also impact high-altitudes through modified wave driving?<br />
<br />
* Do long-term observations of climatological wave properties at high altitudes show evidence of long-term change consistent with changes in the wave filtering environment?<br />
<br />
* Do simpler models (e.g., ray tracing, quasi-geostrophic codes) show evidence of robust long-term changes in upper-atmospheric waves due to a changed wave filtering environment?<br />
<br />
== References ==<br />
<br />
Butchart, N., I. Cionni, V. Eyring, D.W.Waugh, H. Akiyoshi, J. Austin, C. Brühl, M. P. Chipperfield, E. Cordero, M. Dameris, R. Deckert, S. M. Frith, R. R. Garcia, A. Gettelman, M. A. Giorgetta, D. E. Kinnison, F. Li, E. Mancini, C. McLandress, S. Pawson, G. Pitari, D. A. Plummer, E. Rozanov, F. Sassi, J. F. Scinocca, T. G. Shepherd, K. Shibata, and W. Tian (2010) Chemistry-climate model simulations of 21st century stratospheric climate and circulation changes, J. Clim. (in press).<br />
<br />
Eyring, V., et al. (2007), Multimodel projections of stratospheric ozone in the 21st century, J. Geophys. Res., 112, D16303, doi:10.1029/2006JD008332.<br />
<br />
Garcia, R. R. and F. Sassi (1999), Modulation of the mesospheric semiannual oscillation by the quasibiennial oscillation, Earth Planets Space, 51, 563-569. <br />
<br />
Gillett, N. P., and D. W. J. Thompson (2003), Simulation of recent Southern Hemisphere climate change, Science, 302, 273–275.<br />
<br />
Goncharenko, L., and S.-R. Zhang (2008), Ionospheric signatures of sudden stratospheric warming: Ion temperature at middle latitude, Geophys. Res. Lett., 35, L21103, doi:10.1029/2008GL035684.<br />
<br />
Hagan, M. E., M. D. Burrage, J. M. Forbes, J. Hackney, W. J. Randel, and X. Zhang (1999), QBO effects on the diurnal tide in the upper atmosphere, Earth Planets Space, 51, 571–578.<br />
<br />
McLandress, C. and T. G. Shepherd (2009a), Simulated anthropogenic changes in the Brewer-Dobson circulation, including its extension to high altitudes, J. Clim. 22, 1516-1540.<br />
<br />
McLandress, C. and T. G. Shepherd (2009b), Impact of climate change on stratospheric sudden warmings as simulated by the Canadian Middle Atmosphere Model, J. Clim. 22, 5449-5463.<br />
<br />
Pedatella , N. M. and J. M. Forbes (2010), Evidence for stratosphere sudden warming‐ionosphere coupling due to vertically propagating tides, Geophys. Res. Lett., 37, L11104, doi:10.1029/2010GL043560.<br />
<br />
Siskind, D. E., S. D. Eckermann, L. Coy, J. P. McCormack, and C. E. Randall (2007), On recent interannual variability of the Arctic winter mesosphere: Implications for tracer descent, Geophys. Res. Lett., 34, L09806, doi:10.1029/2007GL029293.<br />
<br />
Siskind, D. E., S. D. Eckermann, J. P. McCormack, L. Coy, K. W. Hoppel, and N. L. Baker (2010), Case studies of the mesospheric response to recent minor, major and extended stratospheric warmings, J. Geophys. Res., (in press).<br />
<br />
Son, S.-W., N. F. Tandon, L. M. Polvani, and D. W. Waugh (2009), Ozone hole and Southern Hemisphere climate change, Geophys. Res. Lett., 36, L15705, doi:10.1029/2009GL038671.<br />
<br />
Wu, Q., S. C. Solomon, Y.-H. Kuo, T. L. Killeen, and J. Xu (2009), Spectral analysis of ionospheric electron density and mesospheric neutral wind diurnal nonmigrating tides observed by COSMIC and TIMED satellites, Geophys. Res. Lett., 36, L14102, doi:10.1029/2009GL038933.<br />
<br />
== Related meetings ==<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011.</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.1_Changes_in_wave_sourcesProject 1.1 Changes in wave sources2010-07-14T08:44:10Z<p>Marsh: </p>
<hr />
<div>* Co-leaders: Kaoru Sato (JP), Jadwiga (Yaga) H. Richter (US)<br />
<br />
== Goal ==<br />
<br />
''To assess changes in GW sources in response to a changing climate''<br />
<br />
== Tools ==<br />
<br />
1. GCMs with parameterized GW sources: comparison of parameterized waves in long-term simulations (convection, fronts, orography)<br />
<br />
2. High resolution GCMs (~25 km): look at changes in frontally and orographically excited waves in long-term simulations<br />
<br />
3. Radar and Lidar Observations: look at trends in GWs in the MLT and compare to models<br />
<br />
== Related meetings ==<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-07-14T08:42:01Z<p>Marsh: /* Existing work and plans */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US), Elisa Manzini (IT)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: M.Bittner (DE), J.Scheer (AR), S.Gurubaran (IN), D.Murphy (AU) J. Lastovicka (CZ), D.Pancheva (BG), E. Merzlyakov (RU)<br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) was held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which was also held in Boulder.<br />
<br />
AGU Chapman Conference on Atmospheric Gravity Waves and Their Effects on General Circulation and Climate<br />
Honolulu, Hawaii, 28 February – 4 March 2011 [http://www.agu.org/meetings/chapman/2011/ccall/]<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-06-14T16:51:21Z<p>Marsh: /* How will Geospace Respond to a Changing Climate? */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (US)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US), Elisa Manzini (IT)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: M.Bittner (DE), J.Scheer (AR), S.Gurubaran (IN), D.Murphy (AU) J. Lastovicka (CZ), D.Pancheva (BG), E. Merzlyakov (RU)<br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: L. Alfonsi (Italy), A. Elias (Argentina), M. Mlynczak (US), H. Schmidt (DE), S.-R. Zhang (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (US), , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (US), N. Pertsev (RU)<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.1_Changes_in_wave_sourcesProject 1.1 Changes in wave sources2010-06-14T16:48:11Z<p>Marsh: </p>
<hr />
<div>* Co-leaders: Kaoru Sato (JP), Jadwiga (Yaga) H. Richter (US)<br />
<br />
== Goal ==<br />
<br />
''To assess changes in GW sources in response to a changing climate''<br />
<br />
== Tools ==<br />
<br />
1. GCMs with parameterized GW sources: comparison of parameterized waves in long-term simulations (convection, fronts, orography)<br />
<br />
2. High resolution GCMs (~25 km): look at changes in frontally and orographically excited waves in long-term simulations<br />
<br />
3. Radar and Lidar Observations: look at trends in GWs in the MLT and compare to models</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-04-12T15:43:06Z<p>Marsh: /* Introduction */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite, are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US), Elisa Manzini (IT)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (USA, , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (USA), N. Pertsev (Russia)<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-04-11T21:34:37Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US), Elisa Manzini (IT)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (USA, , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (USA), N. Pertsev (Russia)<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/ConferencesConferences2010-03-12T23:08:01Z<p>Marsh: Created page with 'The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmosp...'</p>
<hr />
<div>The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-03-12T23:04:47Z<p>Marsh: </p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members: M. DeLand (USA, , B. Karlsson (Sweden), S. Kirkwood (Sweden), A. Klekociuk (Australia), A. Merkel (USA), N. Pertsev (Russia)<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-02-27T02:11:02Z<p>Marsh: </p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-02-27T02:09:07Z<p>Marsh: </p>
<hr />
<div>[[Link title]]=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.<br />
<br />
== Key Linkages ==<br />
* Cross-task project with Task Group 4 (project 5)</div>Marshhttp://www.cawses.org/wiki/index.php/December_2009_PMC_Trend_Meeting_Report_(submitted_to_EOS)December 2009 PMC Trend Meeting Report (submitted to EOS)2010-02-17T17:22:39Z<p>Marsh: /* Workshop on Modeling Polar Mesospheric Cloud Trends */</p>
<hr />
<div>Mesospheric ice clouds as indicators of upper atmosphere climate change<br />
<br />
== Workshop on Modeling Polar Mesospheric Cloud Trends ==<br />
<br />
Boulder, Colorado, Dec. 10-11, 2009<br />
<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year timeseries of SBUV (Solar Backscatter Ultraviolet) satellite measurements. SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable.<br />
<br />
General circulation models (GCM's) that simulate MC have finally reached the sophistication to address this question. Two modeling groups have reported simulating trends in MC optical properties, which closely match the SBUV data. The models are (1) LIMA/ICE model (Leibniz Institute Middle Atmosphere model/Ice) and (2) WACCM-PMC (Whole Atmosphere Community Climate Model-Polar Mesospheric Clouds). Both model simulations agree well with the satellite data in the northern hemisphere (NH). Trends of southern MC are apparently masked by large interannual variability.<br />
<br />
To understand how two different simulations could produce such remarkable agreement, MC scientists recently attended an informal workshop at the Laboratory for Atmospheric Physics in Boulder. <br />
<br />
Changes of mesospheric temperature and H2O from 1953 to 2003 result from a host of long-term forcings, including changes in greenhouse gases (GHG). Simulations covering the range 0-140 km indicate a negligibly small (<0.4K/decade) cooling in the MC domain (the high-latitude summertime mesopause region, 80-90 km). A simulated 10-15%/decade increase of H2O results in part from oxidation of rising concentrations of methane. This study (with no ice modeling) points toward H2O as the possible driving force for MC trends. Use of the same long-term forcing in WACCM-PMC (with an ice parameterization) showed excellent agreement with SBUV trends in the NH polar region. <br />
<br />
To investigate the stratospheric influences on the NH mesosphere, LIMA/ICE, with a Lagrangian formulation of MC, was 'nudged' from below ~40 km by observed winds over period 1961 to 2008. GHG concentrations were held constant. A small mesospheric cooling rate (~1K/decade) was found to be partly due to atmospheric contraction owing to stratospheric cooling. Yet even this model simulated the observed trend in MC, despite the lack of any explicit methane or CO2 trends in the mesosphere!<br />
<br />
Subsequent discussion considered unmodeled influences (e.g space shuttle injections of water and detailed nucleation schemes). None were considered to be of major importance for MC trends. Interhemispheric coupling is implicit in both models but its influence has not been separately isolated.<br />
<br />
Although the WACCM model predicts realistic upper stratospheric cooling (~1K/decade), it is difficult to segregate its influence in a free-running model. Future work will include sensitivity calculations in which the various forcings are held constant. The LIMA/ICE modeling group plans realistic optical calculations, coupling between chemistry and dynamics, and the addition of GHG increases. Progress should be forthcoming before the next meeting of the IAGA/ICMA/CAWSES Workshop on Long-term Changes and Trends in the Atmosphere, to be held in Boulder, Colorado on June 15-18, 2010.</div>Marshhttp://www.cawses.org/wiki/index.php/December_2009_PMC_Trend_Meeting_Report_(submitted_to_EOS)December 2009 PMC Trend Meeting Report (submitted to EOS)2010-02-17T17:22:11Z<p>Marsh: Created page with 'Mesospheric ice clouds as indicators of upper atmosphere climate change == Workshop on Modeling Polar Mesospheric Cloud Trends == Boulder, Colorado, Dec. 10-11, 2009 The 20-yr...'</p>
<hr />
<div>Mesospheric ice clouds as indicators of upper atmosphere climate change<br />
<br />
== Workshop on Modeling Polar Mesospheric Cloud Trends ==<br />
<br />
Boulder, Colorado, Dec. 10-11, 2009<br />
<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year timeseries of SBUV (Solar Backscatter Ultraviolet) satellite measurements. SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable.<br />
<br />
General circulation models (GCM's) that simulate MC have finally reached the sophistication to address this question. Two modeling groups have reported simulating trends in MC optical properties, which closely match the SBUV data. The models are (1) LIMA/ICE model (Leibniz Institute Middle Atmosphere model/Ice) and (2) WACCM-PMC (Whole Atmosphere Community Climate Model-Polar Mesospheric Clouds). Both model simulations agree well with the satellite data in the northern hemisphere (NH). Trends of southern MC are apparently masked by large interannual variability.<br />
<br />
To understand how two different simulations could produce such remarkable agreement, MC scientists recently attended an informal workshop at the Laboratory for Atmospheric Physics in Boulder. <br />
<br />
Changes of mesospheric temperature and H2O from 1953 to 2003 result from a host of long-term forcings, including changes in greenhouse gases (GHG). Simulations covering the range 0-140 km indicate a negligibly small (<0.4K/decade) cooling in the MC domain (the high-latitude summertime mesopause region, 80-90 km). A simulated 10-15%/decade increase of H2O results in part from oxidation of rising concentrations of methane. This study (with no ice modeling) points toward H2O as the possible driving force for MC trends. Use of the same long-term forcing in WACCM-PMC (with an ice parameterization) showed excellent agreement with SBUV trends in the NH polar region. <br />
<br />
To investigate the stratospheric influences on the NH mesosphere, LIMA/ICE, with a Lagrangian formulation of MC, was 'nudged' from below ~40 km by observed winds over period 1961 to 2008. GHG concentrations were held constant. A small mesospheric cooling rate (~1K/decade) was found to be partly due to atmospheric contraction owing to stratospheric cooling. Yet even this model simulated the observed trend in MC, despite the lack of any explicit methane or CO2 trends in the mesosphere!<br />
<br />
Subsequent discussion considered unmodeled influences (e.g space shuttle injections of water and detailed nucleation schemes). None were considered to be of major importance for MC trends. Interhemispheric coupling is implicit in both models but its influence has not been separately isolated.<br />
<br />
Although the WACCM model predicts realistic upper stratospheric cooling (~1K/decade), it is difficult to segregate its influence in a free-running model. Future work will include sensitivity calculations in which the various forcings are held constant. The LIMA/ICE modeling group plans realistic optical calculations, coupling between chemistry and dynamics, and the addition of GHG increases. Progress should be forthcoming before the next meeting of the IAGA/ICMA/CAWSES Workshop on Long-term Changes and Trends in the Atmosphere, to be held in Boulder, Colorado on June 15-18, 2010.</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2010-02-17T17:19:45Z<p>Marsh: </p>
<hr />
<div>* Project leaders: G.Thomas, U.Berger<br />
* Project members:<br />
<br />
<br />
[[December 2009 PMC Trend Meeting Report (submitted to EOS)]]</div>Marshhttp://www.cawses.org/wiki/index.php/Project_3_PMC/NLC_altitude,_frequency_and_brightness_changes_related_to_changes_in_dynamics_and_chemical_compositionProject 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition2010-02-17T17:18:08Z<p>Marsh: </p>
<hr />
<div>* Project leaders: G.Thomas, U.Berger<br />
* Project members:<br />
<br />
<br />
[[Meeting Report (submitted to EOS):]]</div>Marshhttp://www.cawses.org/wiki/index.php/Meeting_Report_(submitted_to_EOS):Meeting Report (submitted to EOS):2010-02-17T17:15:58Z<p>Marsh: </p>
<hr />
<div>Mesospheric ice clouds as indicators of upper atmosphere climate change<br />
<br />
'''Workshop on Modeling Polar Mesospheric Cloud Trends'''<br />
<br />
Boulder, Colorado, Dec. 10-11, 2009<br />
<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year timeseries of SBUV (Solar Backscatter Ultraviolet) satellite measurements. SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable.<br />
<br />
General circulation models (GCM's) that simulate MC have finally reached the sophistication to address this question. Two modeling groups have reported simulating trends in MC optical properties, which closely match the SBUV data. The models are (1) LIMA/ICE model (Leibniz Institute Middle Atmosphere model/Ice) and (2) WACCM-PMC (Whole Atmosphere Community Climate Model-Polar Mesospheric Clouds). Both model simulations agree well with the satellite data in the northern hemisphere (NH). Trends of southern MC are apparently masked by large interannual variability.<br />
<br />
To understand how two different simulations could produce such remarkable agreement, MC scientists recently attended an informal workshop at the Laboratory for Atmospheric Physics in Boulder. <br />
<br />
Changes of mesospheric temperature and H2O from 1953 to 2003 result from a host of long-term forcings, including changes in greenhouse gases (GHG). Simulations covering the range 0-140 km indicate a negligibly small (<0.4K/decade) cooling in the MC domain (the high-latitude summertime mesopause region, 80-90 km). A simulated 10-15%/decade increase of H2O results in part from oxidation of rising concentrations of methane. This study (with no ice modeling) points toward H2O as the possible driving force for MC trends. Use of the same long-term forcing in WACCM-PMC (with an ice parameterization) showed excellent agreement with SBUV trends in the NH polar region. <br />
<br />
To investigate the stratospheric influences on the NH mesosphere, LIMA/ICE, with a Lagrangian formulation of MC, was 'nudged' from below ~40 km by observed winds over period 1961 to 2008. GHG concentrations were held constant. A small mesospheric cooling rate (~1K/decade) was found to be partly due to atmospheric contraction owing to stratospheric cooling. Yet even this model simulated the observed trend in MC, despite the lack of any explicit methane or CO2 trends in the mesosphere!<br />
<br />
Subsequent discussion considered unmodeled influences (e.g space shuttle injections of water and detailed nucleation schemes). None were considered to be of major importance for MC trends. Interhemispheric coupling is implicit in both models but its influence has not been separately isolated.<br />
<br />
Although the WACCM model predicts realistic upper stratospheric cooling (~1K/decade), it is difficult to segregate its influence in a free-running model. Future work will include sensitivity calculations in which the various forcings are held constant. The LIMA/ICE modeling group plans realistic optical calculations, coupling between chemistry and dynamics, and the addition of GHG increases. Progress should be forthcoming before the next meeting of the IAGA/ICMA/CAWSES Workshop on Long-term Changes and Trends in the Atmosphere, to be held in Boulder, Colorado on June 15-18, 2010.</div>Marshhttp://www.cawses.org/wiki/index.php/Meeting_Report_(submitted_to_EOS):Meeting Report (submitted to EOS):2010-02-17T17:13:48Z<p>Marsh: Created page with 'Mesospheric ice clouds as indicators of upper atmosphere climate change Workshop on Modeling Polar Mesospheric Cloud Trends Boulder, Colorado, Dec. 10-11, 2009 The 20-yr old sp...'</p>
<hr />
<div>Mesospheric ice clouds as indicators of upper atmosphere climate change<br />
<br />
Workshop on Modeling Polar Mesospheric Cloud Trends<br />
Boulder, Colorado, Dec. 10-11, 2009<br />
<br />
The 20-yr old speculation that high-altitude summertime ice clouds (polar mesospheric clouds or noctilucent clouds, here denoted MC) are affected by anthropogenic activities has recently received support from a 30-year timeseries of SBUV (Solar Backscatter Ultraviolet) satellite measurements. SBUV data reveal a significant trend in bright MC properties. However, the robustness of the trend, extracted from interannual, local-time and solar-cycle variability, and its underlying causes remains debatable.<br />
General circulation models (GCM's) that simulate MC have finally reached the sophistication to address this question. Two modeling groups have reported simulating trends in MC optical properties, which closely match the SBUV data. The models are (1) LIMA/ICE model (Leibniz Institute Middle Atmosphere model/Ice) and (2) WACCM-PMC (Whole Atmosphere Community Climate Model-Polar Mesospheric Clouds). Both model simulations agree well with the satellite data in the northern hemisphere (NH). Trends of southern MC are apparently masked by large interannual variability.<br />
To understand how two different simulations could produce such remarkable agreement, MC scientists recently attended an informal workshop at the Laboratory for Atmospheric Physics in Boulder. <br />
Changes of mesospheric temperature and H2O from 1953 to 2003 result from a host of long-term forcings, including changes in greenhouse gases (GHG). Simulations covering the range 0-140 km indicate a negligibly small (<0.4K/decade) cooling in the MC domain (the high-latitude summertime mesopause region, 80-90 km). A simulated 10-15%/decade increase of H2O results in part from oxidation of rising concentrations of methane. This study (with no ice modeling) points toward H2O as the possible driving force for MC trends. Use of the same long-term forcing in WACCM-PMC (with an ice parameterization) showed excellent agreement with SBUV trends in the NH polar region. <br />
<br />
To investigate the stratospheric influences on the NH mesosphere, LIMA/ICE, with a Lagrangian formulation of MC, was 'nudged' from below ~40 km by observed winds over period 1961 to 2008. GHG concentrations were held constant. A small mesospheric cooling rate (~1K/decade) was found to be partly due to atmospheric contraction owing to stratospheric cooling. Yet even this model simulated the observed trend in MC, despite the lack of any explicit methane or CO2 trends in the mesosphere!<br />
<br />
Subsequent discussion considered unmodeled influences (e.g space shuttle injections of water and detailed nucleation schemes). None were considered to be of major importance for MC trends. Interhemispheric coupling is implicit in both models but its influence has not been separately isolated.<br />
<br />
Although the WACCM model predicts realistic upper stratospheric cooling (~1K/decade), it is difficult to segregate its influence in a free-running model. Future work will include sensitivity calculations in which the various forcings are held constant. The LIMA/ICE modeling group plans realistic optical calculations, coupling between chemistry and dynamics, and the addition of GHG increases. Progress should be forthcoming before the next meeting of the IAGA/ICMA/CAWSES Workshop on Long-term Changes and Trends in the Atmosphere, to be held in Boulder, Colorado on June 15-18, 2010.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-02-17T17:08:42Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig (IN), C. Jacobi (DE)<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert (US), L. Qian (US)<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22010-02-17T17:06:32Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: S. Eckermann (US)<br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig, C. Jacobi<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert, L. Qian<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US), U. Berger (DE)<br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.1_Changes_in_wave_sourcesProject 1.1 Changes in wave sources2009-11-23T18:24:06Z<p>Marsh: </p>
<hr />
<div>* Co-leaders: Kaoru Sato (JP), Jadwiga (Yaga) H. Richter (US)</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22009-11-23T18:21:22Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: Jadwiga (Yaga) Richter (US), Kaoru Sato (JP)<br />
<br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: G. Beig, C. Jacobi<br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: J. Emmert, L. Qian<br />
* Project members: Marty Mlynczak (US)<br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US)<br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22009-10-16T17:25:14Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: <br />
* Project members: <br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: G.E. Thomas (US)<br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22009-10-15T21:36:19Z<p>Marsh: /* Introduction */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
Radiative, chemical, and dynamical forcing from below contributes to disturbances of the upper atmosphere. In response to rising greenhouse gas concentrations, cooling in the middle atmosphere will alter the complex physical and chemical processes of this region. Patterns of cooling and contraction of the upper atmosphere are emerging from model studies and observations, consistent with a strong connection to changes in the lower atmosphere. Recent changes in noctilucent cloud distributions, now observed on a global scale by the AIM satellite (see figure above), are thought to be symptomatic of cooling temperatures in the upper atmosphere. Rising greenhouse gas concentrations alter the ionosphere in a variety of ways and could be transmitted to the magnetosphere. These changes may have unforeseen consequences for space-related technologies and societal infrastructures<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: <br />
* Project members: <br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: <br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22009-10-15T21:31:35Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
storm tracks, mountain waves, convection and stratospheric heating rates<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
Changes of background winds due to CO2 trends and ozone layer changes<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: <br />
* Project members: <br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: <br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.3_Changes_in_MLTI_dynamics_and_compositionProject 1.3 Changes in MLTI dynamics and composition2009-10-15T21:23:33Z<p>Marsh: Created page with '* Project leaders: * Project members:'</p>
<hr />
<div>* Project leaders:<br />
* Project members:</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.2_Changes_in_filteringProject 1.2 Changes in filtering2009-10-15T21:23:11Z<p>Marsh: Created page with '* Project leaders: * Project members:'</p>
<hr />
<div>* Project leaders:<br />
* Project members:</div>Marshhttp://www.cawses.org/wiki/index.php/Project_1.1_Changes_in_wave_sourcesProject 1.1 Changes in wave sources2009-10-15T21:22:23Z<p>Marsh: Created page with '* Co-leaders'</p>
<hr />
<div>* Co-leaders</div>Marshhttp://www.cawses.org/wiki/index.php/Task_2Task 22009-10-15T21:21:47Z<p>Marsh: /* Scientific issues */</p>
<hr />
<div>=How will Geospace Respond to a Changing Climate?=<br />
<br />
Co-leaders:<br />
* Jan Lastovicka (CZ)<br />
* Daniel Marsh (USA)<br />
<br />
==Introduction==<br />
<br />
==Scientific issues==<br />
Task Group 2 will focus on answering these three key questions over the next 4 years:<br />
<br />
1. How do changes in tropospheric wave generation and their propagation through a changing atmosphere affect the dynamics of the MLT?<br />
<br />
2. By how much is the anthropogenic effect on the ionosphere/thermosphere enhanced during a quiet sun period?<br />
<br />
3. Are PMC/NLC characteristics trending?<br />
<br />
To answer these questions, five projects are established characterize and understand the impacts of:<br />
<br />
[[Project 1.1 Changes in wave sources]]<br />
<br />
[[Project 1.1 Changes in wave sources (storm tracks, mountain waves, convection and stratospheric heating rates).]]<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.2 Changes in filtering]]<br />
<br />
[[Project 1.2 Changes in filtering (changes of background winds due to CO2 trends and ozone layer changes).]]<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition]]<br />
<br />
[[Project 1.3 Changes in MLTI dynamics and composition.]]<br />
* Project leaders: <br />
* Project members: <br />
<br />
[[Project 2 The enhancement of the anthropogenic effect on the ionosphere/thermosphere during a quiet sun period.]]<br />
* Project leaders: <br />
* Project members: <br />
[[Project 3 PMC/NLC altitude, frequency and brightness changes related to changes in dynamics and chemical composition.]]<br />
* Project leaders: <br />
* Project members:<br />
<br />
== Existing work and plans ==<br />
<br />
<br />
The 6th IAGA/ICMA/CAWSES workshop on “Long-Term Changes and Trends in the Atmosphere” (http://www.hao.ucar.edu/TREND2010/index.php) will be held at National Center for Atmospheric Research (NCAR) Center Green Conference Center, Boulder, Colorado, USA, June15-18, 2010, the week before the 2010 CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) workshop, which will also be held in Boulder.</div>Marshhttp://www.cawses.org/wiki/index.php/Changes_in_wave_sourcesChanges in wave sources2009-10-15T21:18:11Z<p>Marsh: Created page with '* Project leaders: * Project members:'</p>
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<div>* Project leaders: <br />
* Project members:</div>Marshhttp://www.cawses.org/wiki/index.php/Changes_in_MLTI_dynamics_and_compositionChanges in MLTI dynamics and composition2009-10-15T21:17:53Z<p>Marsh: Created page with '* Project leaders: * Project members:'</p>
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<div>* Project leaders: <br />
* Project members:</div>Marshhttp://www.cawses.org/wiki/index.php/Changes_in_filteringChanges in filtering2009-10-15T21:17:38Z<p>Marsh: Created page with '* Project leaders: * Project members:'</p>
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<div>* Project leaders: <br />
* Project members:</div>Marsh