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On the variability of total electron content over Europe during the 2009 and 2019 Northern Hemisphere SSWs
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  • Tarique Adnan Siddiqui,
  • Yosuke Yamazaki,
  • Claudia Stolle,
  • Astrid Maute,
  • Jan Lastovička,
  • Ilya Edemskiy,
  • Zbyšek Mošna
Tarique Adnan Siddiqui
Leibniz Institute of Atmospheric Physics

Corresponding Author:siddiqui@iap-kborn.de

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Yosuke Yamazaki
GFZ German Research Centre for Geosciences
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Claudia Stolle
GFZ Potsdam
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Astrid Maute
National Center for Atmospheric Research (UCAR)
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Jan Lastovička
Institute of Atmospheric Physics of the Czech Academy of Sciences, Bocni II, 14131 Prague 4, Czech Republic
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Ilya Edemskiy
Institute of Solar-Terrestrial Physics (RAS)
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Zbyšek Mošna
Institute of Atmospheric Physics Academy CAS
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The nature of the variability of the Total Electron Content (TEC) over Europe is investigated during the 2009 and 2019 Northern Hemisphere (NH) SSW events in this study. As the TEC variability is driven by geomagnetic and lower atmospheric forcing mechanisms, we investigate the dominant drivers and their respective contributions to TEC changes during both SSW events. We simulate the SSWs using the Whole Atmosphere Community Climate Model eXtended version (WACCM-X) and compare the semidiurnal solar and lunar tidal variabilities in the mesosphere-lower thermosphere (MLT) region. Further, in order to assess the mechanisms responsible for the TEC variability during both SSWs, we run numerical experiments using the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM). We constrain the TIE-GCM lower boundary with the WACCM-X fields and carry out simulations both with and without geomagnetic forcing for each of the SSWs. The TIE-GCM simulations allow us to isolate the geomagnetic and lower atmospheric forcing effects on the TEC. We find that there was a major enhancement in daytime TEC over Europe during the 2019 SSW event, which was predominantly geomagnetically forced (~80%), while for the 2009 SSW, the major variability in TEC was accounted for by lower atmospheric forcing.
Sep 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 9. 10.1029/2020JA028751