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Understanding the Total Electron Content Variability Over Europe During 2009 and 2019 SSWs
Author(s) -
Siddiqui T. A.,
Yamazaki Y.,
Stolle C.,
Maute A.,
Laštovička J.,
Edemskiy I. K.,
Mošna Z.,
Sivakandan M.
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028751
Subject(s) - tec , total electron content , thermosphere , ionosphere , atmospheric sciences , climatology , northern hemisphere , forcing (mathematics) , gcm transcription factors , environmental science , earth's magnetic field , climate model , geology , general circulation model , geophysics , climate change , physics , oceanography , magnetic field , quantum mechanics
The nature of the variability of the Total Electron Content (TEC) over Europe is investigated during 2009 and 2019 Northern Hemisphere (NH) SSW events in this study by using a combination of Global Navigation Satellite System (GNSS) based TEC observations and Thermosphere‐Ionosphere Electrodynamics General Circulation Model (TIE‐GCM) simulations. To simulate the SSW effects in TIE‐GCM, the dynamical fields from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM‐X) simulations of 2009 and 2019 SSWs are specified at the TIE‐GCM lower boundary. The observed and simulated TEC are in overall good agreement and therefore the simulations are used to understand the sources of mid‐latitude TEC variability during both SSWs. Through comparison of TIE‐GCM simulations with and without geomagnetic forcing, we find that the TEC variability during the 2019 SSW event, was predominantly geomagnetically forced, while for the 2009 SSW, the major variability in TEC was accounted for by the changes in vertically propagating migrating semidiurnal solar (SW2) and lunar (M2) tides. By comparing the TIE‐GCM simulations with and without the SW2 and M2 tides, we find that these semidiurnal tides contribute to ∼ 20%–25% increase in the quiet background TEC.