Understanding nighttime ionospheric depletions associated with sudden stratospheric warmings in the American sector

Performing a set of numerical experiments with the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) constrained by a high-altitude version of the Navy Global Environmental Model, we demonstrate that this nighttime ionospheric hole was the result of increased poleward and down magnetic field line plasma motion at low and midlatitudes in response to altered F-region neutral meridional winds.

Thermospheric meridional wind modifications that produced this nighttime depletion resulted from the well-known enhancements in semidiurnal tidal amplitudes associated with stratospheric warming (SSWs) in the upper mesosphere and thermosphere. Investigations into other deep nighttime ionospheric depletions and their cause were also considered. Measurements of total electron content from Global Navigation Satellite System receivers and additional constrained TIME-GCM simulations showed that nighttime ionospheric depletions were also observed on several nights during the January-February 2010 SSW, which resulted from the same forcing mechanisms as those observed in January 2013.