Task 4 Project 5

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Contents

How do thunderstorm activities interact with the atmosphere, ionosphere and magnetosphere?

Project leaders

Yukihiro Takahashi (Japan) / Colin Price (Israel) / Earl Williams (USA)

Project members (tentative)

Mitsuteru Sato (Japan), Toru Adachi (Japan), Gabriella Satori (Hungary), Umran Inan (USA), Walter Lyons (USA), Steven Cummer (USA), Victor Pasko (USA), Torsten Neubert (Denmark), Elisabeth Blanc (France), Thomas Farges (France), Ute Evert (Netherland), Yoav Yair (Israel), Michi Nishioka (Japan), Masashi Kamogawa (Japan), Yasutaka Hiraki (Japan), Carl-Fredrik Enell (Finland), Alfred Chen (Taiwan), David Smith (USA), Michel Rycroft (UK), Martin Fullekurg (UK), Fernando Saosabbas (Brazil), Enrico A (Bologna University)

Project overview

In the past two decades the understanding of atmospheric electricity made a great progress by regional and global mappings of lightning discharge with ground-based and spaceborne instruments and by discoveries of unrecognized phenomena, such as TLEs and TGFs. Here we focus on the following topics to connect different altitudes both via electromagnetic processes and via dynamic processes relating to discharges.

  1. Investigate dynamical effect of thunderstorm activity in the middle and upper atmosphere, including wave-4 structures.
  2. Investigate the effect of electrical discharges on ion/electron density in the ionosphere and atmospheric constituents.
  3. Establish the global electric circuit model, covering surface, atmosphere, ionosphere and magnetosphere.
  4. Investigate the relationship between high energy particles and thunderstorms.
  5. Investigate the relationship between thunderstorm and solar activities. (collaborating with TG1)

Project plan

1) Investigate dynamical effects of thunderstorm activity in the middle and upper atmosphere, including wave-4 structures.
Thunderstorms cause gravity waves and mesoscale vertical circulation, which reach the middle atmosphere. These dynamical motions of the atmosphere may cause wave-4 structure observed in the upper atmosphere and ionosphere. Global lightning data obtained by ground-based network and earth-orbiting satellites will be compared with the structures at higher altitudes.
2) Investigate the effect of electrical discharges on ion/electron density in the ionosphere and atmospheric constituents.
It has been revealed that lightning discharge induces a significant increase or decrease of electron density in the ionosphere both by observation and by numerical calculation. Also it is expected that the lightning discharge induces enhancement of chemical reactions in the lower and middle atmosphere. These reactions may modify abundance of ozone and NOx. The quantitative assessments of discharge effects will be made based on the spacecraft measurements as well as theoretical modeling.
3) Establish the global electric circuit model, covering surface, atmosphere, ionosphere and magnetosphere.
Although the hypothesis of global electric circuit model was proposed almost 100 years ago, understanding of this model is still at a very early stage and quantitative evidence is quite poor. Taking into account the latest observational datasets and numerical modeling will redraw this model with some essential qualitative revisions.
4) Investigate the relationship between high energy particles and thunderstorms.
It is proposed that some part of high energy electrons detected in the magnetosphere is provided by lightning discharges. Also the high energy electrons may initiate high altitude discharges such as sprites. On the other hand, high energy particles including radiation belt particles, and galactic and solar cosmic-rays could ionize the atmospheric molecules and atoms, which may result in generation of cloud particles as well as modification of atmospheric conductivity. Comparison between particle measurements by spacecrafts and those by lightning detection networks will clarify if such mechanism is quantitatively valid or not.
5) Investigate the relationship between thunderstorm and solar activities (collaborating with TG1).
A large number of ideas to explain the relationship between solar activity and the earth’s climate have been submitted over many years. One of the important scenarios that should be examined carefully is the electrical connection between atmospheric current driven by thunderstorm and the ionospheric currents driven by the interaction between solar wind and geomagnetic field. The vertical electric field modulated by the horizontal anomaly of the ionospheric potential caused by solar activity may induce the change of vertical distribution of ions, which affect the production rate of cloud particles. Or the modulated vertical field may change the lifetime of clouds.

Project activities

Coming soon.

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