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  • Thermospheric Responses to ...
    Gan, Quan; Eastes, Richard W.; Wu, Yen‐Jung; Qian, Liying; Cai, Xuguang; Wang, Wenbin; England, Scott L.; McClintock, William E.

    Geophysical research letters, 16 January 2024, Letnik: 51, Številka: 1
    Journal Article

    Leveraging observations by two NASA missions—GOLD (Global‐scale Observations of the Limb and Disk) and ICON (Ionospheric Connection Explorer), we investigate concurrent responses of thermospheric composition, temperatures, and neutral winds to the geomagnetic storm on 3–4 November 2021, as well as their interplay at low and middle latitudes. The synergetic observations reveal remarkable depletions up to 60%–70% in GOLD O/N2, along with large enhancements in GOLD temperatures poleward of 30° in the middle thermosphere. Meridional winds from ICON observations are altered by ∼100 m/s equatorward of 25°N latitude and at 250 km, characterized by a reversal of prevailing northward winds to geomagnetic storm‐driven southward winds. This study fills a need, after a decade‐long gap, for observing concurrent and co‐located responses of composition, temperatures, and neutral winds in the thermosphere to geomagnetic storms. Plain Language Summary Geomagnetic storms, arising from solar wind shocks emitted from the Sun, deposit a large portion of the absorbed solar energy into the Earth's high‐latitude atmosphere through Joule heating and high energy particle heating. Accurate prediction of the responses to geomagnetic storms in the thermosphere‐ionosphere is one of the core scientific objectives of space weather. The recently launched Global‐scale Observations of the Limb and Disk (GOLD) and Ionospheric Connection Explorer (ICON) missions provides an unparalleled opportunity to assess storm‐induced concurrent changes in multiple key parameters. During a G3 geomagnetic storm on 3 November 2021, GOLD observed the substantial changes of 60%–70% in thermosphere column density ratios of atomic oxygen to molecular nitrogen and temperatures. Exceptional meridional winds of 100–200 m/s were also seen by ICON over a broad altitude range. Such observations fill a decades‐long need for simultaneous observations of the key variables in the ionosphere‐thermosphere system. Key Points Remarkable depletions in O/N2 and enhancements in temperature, up to 60%–70%, are seen by Global‐scale Observations of the Limb and Disk during the geomagnetic storm Averaged southward wind deviations of ∼100 m/s are observed by Ionospheric Connection Explorer, coincident with the largest gradient in O/N2 depletions Both O/N2 and temperatures recover rapidly from the disturbed states to pre‐storm states