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

Daytime thermospheric O and N2 column density ratio (∑O/N2) observed by Global-scale Observations of the Limb and Disk 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 h) 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.