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Day-to-day variability of the semidiurnal tide in the F-region ionosphere during the January 2021 SSW from COSMIC-2 and ICON
  • Jens Oberheide
Jens Oberheide
Clemson University

Corresponding Author:joberhe@clemson.edu

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The semidiurnal tidal spectrum in the F-region ionosphere obtained from hourly COSMIC-2 Global Ionospheric Specification data assimilation is greatly (>50%) enhanced during the January 2021 Sudden Stratospheric Warming (SSW). Moreover, the semidiurnal migrating tidal response in topside electron densities closely follows the day-to-day changes of the 10 hPa, 60oN zonal wind from MERRA-2 during the SSW. The response is similar in the northern and southern crests of the Equatorial Ionization Anomaly (EIA) but persists towards higher magnetic latitudes and the EIA trough. A slight phase shift towards earlier local times is consistent with theoretical expectations of an E-region dynamo driving and agrees with semidiurnal tidal diagnostics of MIGHTI/ICON zonal winds at 105 km. The COSMIC-2 data are the first data set to resolve the tidal weather of the ionosphere on a day-to-day basis and, therefore, provide a new perspective on space weather variability driven by lower and middle atmosphere dynamics.