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Characterization of the Thermospheric Mean Winds and Circulation during Solstice using ICON/MIGHTI Observations
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  • Erdal Yiğit,
  • Manbharat Singh Dhadly,
  • Alexander S. Medvedev,
  • Brian J Harding,
  • Christoph R Englert,
  • Qian Wu,
  • Thomas J. Immel
Erdal Yiğit
George Mason University

Corresponding Author:[email protected]

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Manbharat Singh Dhadly
United States Naval Research Laboratory
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Alexander S. Medvedev
Max Planck Institute for Solar System Research
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Brian J Harding
University of California, Berkeley
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Christoph R Englert
Naval Research Laboratory
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Qian Wu
National Center for Atmospheric Research (UCAR)
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Thomas J. Immel
University of California, Berkeley
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Using the horizontal neutral wind observations from the MIGHTI instrument onboard NASA’s ICON (Ionospheric Connection Explorer) spacecraft with continuous coverage, we determine the climatology of the mean zonal and meridional winds and the associated mean circulation at low- to middle latitudes (10S-45N) for Northern Hemisphere solstice conditions between 90 km and 200 km altitudes, specifically on 20 June 2020 solstice as well as for a one-month period from 8 June-7 July 2020. The data are averaged within appropriate altitude, longitude, latitude, solar zenith angle, and local time bins to produce mean wind distributions. The geographical distributions and local time variations of the mean horizontal circulation are evaluated. The instantaneous horizontal winds exhibit a significant degree of spatiotemporal variability often exceeding ~150 m/s. The daily averaged zonal mean winds demonstrate day-to-day variability. Eastward zonal winds and northward (winter-to-summer) meridional winds are prevalent in the lower thermosphere, which provides indirect observational evidence of the eastward momentum deposition by small-scale gravity waves. The mean neutral winds and circulation exhibit smaller scale structures in the lower thermosphere (90-120 km), while they are more homogeneous in the upper thermosphere, indicating the increasingly dissipative nature of the thermosphere. The mean wind and circulation patterns inferred from ICON/MIGHTI measurements can be used to constrain and validate general circulation models, as well as input for numerical wave models.