Variations in thermosphere composition and ionosphere total electron content under ‘geomagnetically quiet’ conditions at solar-minimum

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Friday, May 28, 2021

We conducted observational and modeling studies of thermospheric composition and ionospheric total electron content (TEC) variations during two geomagnetically quiet periods (maximum Kp=1.7) at solar minimum. Daytime thermospheric O and N2 column density ratio (∑O/N2) observed by Global-scale Observations of the Limb and Disk (GOLD) and TEC from a network of ground-based Global Navigation Satellites System receivers both exhibited large (∼30% of reference values) and long-lived (5-11 hours) day-to-day variations in roughly the same mid-latitude geographic regions. Numerical simulations replicated the observed variability, though not perfectly. Analysis of the simulations suggested that the variations were mainly generated in the high-latitudes, and were subsequently advected equatorward and westward. When high-latitudes input was turned off in simulations, the variations were negligible. This suggested the potentially important role of high-latitude geomagnetic forcing in thermospheric composition and ionospheric density variations at mid-latitudes even during some ‘geomagnetically quiet’ periods at solar-minimum.

Tie-GCM Graphic
a) AE index and b) Kp and Dst between DOY 109 and 112. The percentage difference of observed c) ∑O/N2 and d) TEC between DOY 111 and 110 at 15:10 UT. The corresponding percentage difference of ∑O/N2 and TEC simulated by TIE-GCM with Weimer (e and f) and TIE-GCM without Weimer (g and h)
Publication name: Geophysical Research Letter
Authors: Xuguang Cai, Alan G. Burns, Wenbin Wang, Liying Qian, Nicholas Pedatella, Anthea Coster, Shunrong Zhang, Stanley C. Solomon, Richard W. Eastes, Robert E. Daniell, William E. McClintock