Task 1 Project 1


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Task 1 Project 1


What is the effect of transient solar events on the middle and lower atmosphere?

Input for this task is expected from WG3. Output will be used in task 1.3.


  • Irina Mironova (RU)
  • Annika Seppälä (FI)

Proposed active collaborators

  • studies of aerosol, water vapor response of SPE - M. Kulmala (FI), J. Kazil (GER);
  • Energetic particle precipitation – P. Verronen (FI), M. Clilverd (UK), C. Randall (US), C. Rodger (NZ)


Solar Energetic Particle (SEP) events – flux of the charged particles accelerated to high energies during solar flares and/or coronal mass ejections. These particles are mostly protons and heaver ions with energy ranging from a few tens of keV to GeV. Normally SEP penetrate into the upper polar atmosphere, and only during some extremely strong SEP events, called Ground Level Enhancements (GLE), energetic particles can reach the troposphere increasing the ionization rate here. Transient solar events in energetic particles on the Earth atmosphere are events with enhanced energetic particle precipitation (mostly in polar and sub-polar regions) of the duration of hours-days. This gives a unique opportunity to study a direct effect on the atmosphere in case studies.

What is the effect of transient solar events on the mesosphere and upper stratosphere?

  • What we know?

Increased ionization from Energetic Particles precipitating in the atmosphere leads to production of Odd Hydrogen, HOx (H + OH + HO2), and Odd Nitrogen, NOx (N + NO + NO2), in the polar mesosphere and stratosphere between the altitudes of about 30 and 90km. HOx and NOx are families of gases that actively take part in loss of Odd Oxygen (O + O3), including ozone, in the mesosphere and upper stratosphere. Following enhanced energetic particle precipitation from solar storms the amounts of HOx and NOx can significantly increase in the atmosphere leading to observed significant ozone losses in the mesosphere (driven by HOx) and upper stratosphere (driven by NOx). It should be noted that in the case of stratosphere ozone loss typically takes place well above the stratospheric ozone layer.

The HOx gases have a very short chemical lifetime and thus the effect on the atmosphere mainly takes place during and directly after solar storms. The lifetime of NOx gases is strongly dependent on availability of solar light as NOx is removed from the middle atmosphere via photodissociation. Thus during times when little or no sunlight is available i.e. polar night, the NOx produced following solar storms can stay in the atmosphere for several months and be transported to lower altitudes and latitudes outside the polar region. Due to the long lifetime of the NOx gases they can affect the chemical balance of mesosphere and stratosphere for long periods of time, as has been observed from satellite platforms during recent solar storms.


  • What we should do?

What is the effect of transient solar events on the low stratosphere and upper troposphere?

The ultimate goal of this work is to elaborate (probably empirical but better physics based) a quantitative model of the influence of energetic particles on the mid- and low atmosphere.

  • What we know?

One of the atmospheric characteristics that can respond to rapid changes in ionization rate is the atmospheric aerosol content. However, an increase in atmospheric aerosols can only occur in regions where both ions production and trace gases with a possibility to attach to atmospheric ions are present. The maximum ionization rate occurs in the stratospheric layers at about 15–20 km. This corresponds to the altitudes of maximum of sulphuric and nitric acid vapor concentrations and where the formation of stratospheric clouds takes place. It can be supposed that the aerosol particles can be involved in the ion induced aerosol formation scheme.


  • What we should do?

Topical publications

• Yu, F. and Turco, R.: The size-dependent charge fraction of sub-3-nm particles as a key diagnostic of competitive nucleation mechanisms under atmospheric conditions, Atmos. Chem. Phys. Discuss., 11, 11281-11309, doi:10.5194/acpd-11-11281-2011.

• Nieminen, T., Paasonen, P., Manninen, H. E., Sellegri, K., Kerminen, V.-M., and Kulmala, M.: Parameterization of ion-induced nucleation rates based on ambient observations, Atmos. Chem. Phys., 11, 3393-3402, 2011.

• Usoskin, I.G., G. A. Kovaltsov, I. A. Mironova, A. J. Tylka, and W. F. Dietrich, Ionization effect of solar particle GLE events in low and middle atmosphere, Atmos. Chem. Phys., 11, 1979-1988, 2011.

• Usoskin, I. G., G. A. Kovaltsov, and I. A. Mironova, Cosmic ray induced ionization model CRAC:CRII: An extension to the upper atmosphere, J. Geophys. Res., 115, D10302, 2010.

• Jackman, C. H., D. R. Marsh, F. M. Vitt, R. R. Garcia, C. E. Randall, E. L. Fleming, and S. M. Frith: Long-term middle atmospheric influence of very large solar proton events, J. Geophys. Res., 114, D11304, doi:10.1029/2008JD011415, 2009.

• Bazilevskaya, G.A., I.G. Usoskin, E. O. Flueckiger, R. G. Harrison, L. Desorgher, R. Buetikofer, M. B. Krainev, V.S. Makhmutov, Y.I. Stozhkov, A.K. Svirzhevskaya, N.S. Svirzhevsky and G.A. Kovaltsov, Cosmic Ray Induced Ion Production in the Atmosphere, Space Sci. Rev., 137, 149-173, 2008.

• Butikofer, R., Fluckiger, E., Desorgher, L., and Moser, M.: The extreme solar cosmic ray particle event on January 2005 and its influence on the radiation dose rate at aircraft altitude, Sci. Total Env., 391,177–183, 2008.

• Seppälä, A., Clilverd, M. A., Rodger, C. J., Verronen, P. T., and Turunen, E.: The effects of hard-spectra solar proton events on the middle atmosphere, J. Geophys. Res., 113, A11 311, 2008.

• Mironova, I. A., Desorgher, L., Usoskin, I. G., Fluckiger, E. O., and Butikofer, R.: Variations of aerosol optical properties during the extreme solar event in January 2005, Geophys. Res. Lett., 35, L18610, 2008.

• Randall, C. E., Harvey, V. L., Singleton, C. S., Bailey, S. M., Bernath, P. F., Codrescu, M., Nakajima, H., and Russell, J. M.: Energetic particle precipitation effects on the Southern Hemisphere stratosphere in 1992-2005, J. Geophys. Res., 112, D08 308, 2007.

• Jackman, C. H., R. G. Roble, and E. L. Fleming: Mesospheric dynamical changes induced by the solar proton events in October–November 2003, Geophys. Res. Lett., 34, L04812, doi:10.1029/2006GL028328, 2007.

• Semeniuk, K., McConnell, J. C., and Jackman, C. H.: Simulation of the October- November 2003 solar proton events in the CMAM GCM: Comparison with observations, Geophys. Res. Lett., 32, L15S02, 2005.

• Seppälä, A., P. T. Verronen, E. Kyrölä, S. Hassinen, L. Backman, A. Hauchecorne, J. L. Bertaux, and D. Fussen: Solar proton events of October– November 2003: Ozone depletion in the Northern Hemisphere polar winter as seen by GOMOS/Envisat, Geophys. Res. Lett., 31, L19107, doi:10.1029/2004GL021042, 2004

Current projects

• ISSI Team Project: "Geospace coupling to Polar Atmosphere", 2009-2011, (leader Annika Seppälä)

• ISSI Team Project: “Study of cosmic ray influence upon atmospheric processes”, 2010-2012, (leader Irina Mironova)

• EU COST Action ES1005: “Towards a more complete assessment of the impact of solar variability on the Earth’s climate”, 2011-2015 (leader T. Dudok de Wit)

Workshops, Meetings and Conferences

• The 4th HEPPA Workshop (With SPARC-SOLARIS) (http://www2.acd.ucar.edu/heppasolaris), Bourder, CO, USA, Oct 2012

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