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

[PEM12-09] TIEGCM model validation against disturbance winds driven by geomagnetic events in 2020-2022

*Thomas J Immel¹、Lily Oglesby¹、Brian J Harding¹、Astrid Maute²、Yen-Jung Joanne Wu¹、Colin Triplett¹、Gilda Gonzàlez¹ (1.University of California, Berkeley、2.University of Colorado, Boulder)

キーワード：geomagnetic storms, disturbance winds, thermospheric storms, thermospheric winds

The MIGHTI instrument on the Ionospheric Connection Explorer (ICON) mission observed winds in the day- and night-time thermosphere continuously for 3 years (late 2019 to late 2022). Nighttime wind are retrieved by a remote sensing technique from 95-105 km, and again above 180 km, while in daytime the wind measurements are continuous throughout the daytime E- and F-region ionosphere. The ICON mission also incorporates MIGHTI measurements of winds and temperatures into a continuous TIEGCM run for the mission, through the creation of a lower boundary forcing function based on tidal Hough-modes fitted to the wind and temperature data from MIGHTI.
This continuous run is also driven by high latitude forcing based upon Weimer electric-field patterns that depend on the interplanetary magnetic field observations in the solar wind around the first Lagrange point between Earth and the sun. This run therefore contains signatures of forcing originating with both lower atmospheric source and solar wind/magnetospheric inputs. With this one can compare the competing signatures of forcing by the sun and troposphere. This study focuses on 2021 where a period of increasing solar activity exhibited many small storms that were observed by MIGHTI. We evaluate the performance of the TIEGCM model vis-à-vis these storms, and compare runs where the lower boundary forcing is simplified to identify cases where the storm effects are countered by lower atmospheric inputs.