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UP: Fachverband Umweltphysik

UP 8: Physics of the middle atmosphere

UP 8.4: Vortrag

Donnerstag, 21. März 2019, 12:00–12:20, HS 22

Model studies on chemical effects of sprites in relation with satellite measurements — •Holger Winkler¹, Takayoshi Yamada^2,3, Yasuko Kasai^2,3, and Justus Notholt¹ — ¹Institut für Umweltphysik, Universität Bremen — ²Terahertz Technology Research Center, National Institute of Information and Communications Technology, Japan — ³Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Japan.

Sprites are large scale electrical discharges in the mesosphere occurring above active thunderstorm clouds. The strong electric fields in sprites cause electron impact ionization, dissociation and excitation of air molecules and atoms as well as electron attachment to electronegative species. Mainly during the last decade, results of a number of model simulations of chemical sprite effects have been presented. However, until recently, there were no direct measurements of the chemical impact of sprites. Data from the Superconducting Submillimeter-Wave Limb Emission Sounder (SMILES) at the Japanese experiment module of the International Space Station indicate an increase of mesospheric HO₂ after three sprite events. These are the first direct observations of chemical sprite effects, and provide a unique opportunity to test our understanding of the chemical processes in sprites. We present results of plasma chemistry model simulations of sprites in relation with SMILES observations, and analyze the chemical reactions which lead to an increase of mesospheric HO₂ on time-scales of many minutes to a few hours after sprite events.