[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-29] Horizontal wind effects on the thermospheric composition during the geomagnetic storm

*Tingting Yu¹、Zhipeng Ren、Xuguang Cai (1.INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCES)

キーワード：O/N2, geomagnetic storm, horizontal wind

During the 20 April 2020 geomagnetic storm, a long-lived O/N₂ depletion at middle latitudes was observed by GOLD. The observed O/N₂ depletion tilts latitudinally with the lowest latitude of ~20° N at ~75° W, and changes orientation near 75° W, with a north-westward tilt to the west of ~75° W and a north-eastward tilt to the east of ~75°W. The TIEGCM shows the similar O/N₂ depletion patterns and magnitudes. Furthermore, the global simulation shows a neutral ‘tongue’ structure, which is an area of positive O/N₂ variations sandwiched by two regions of negative O/N₂ variations. The neutral 'tongue' was gradually transported to dayside accompanied by dissipation, and was also observed by GOLD during the storm recovery phase. Horizontal wind plays a major role in forming the O/N₂ depletion and neutral ‘tongue’ structure. For the O/N₂ depletion, the high-latitude westward zonal wind and the middle-latitude eastward zonal wind maintained its long existence. While the neutral ‘tongue’ was mainly driven by the poleward wind.