Vertical Profile of the Thermospheric Response to Magnetic Storms at Polar Latitudes

Abstract:

We analyze various neutral measurements at different altitudes over the polar cap region for two magnetic storm events in January 2005, including the neutral temperature at 250 km, the neutral density at 360 km and 470 km, as well as the Poynting flux at about 840 km. All the measurements show enhancements at very high latitude poleward of 80° MLAT implying that substantial heating is supplied to the polar cap during storms. The neutrals at all altitudes respond very quickly to the magnetospheric energy input, indicating quick and strong vertical ion-neutral coupling in polar cap regions. It also suggests that the energy is mainly dissipated at altitudes below 250 km. The neutral temperature changes simulated by NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) are much lower than the observed changes by Fabry-Perot interferometer (FPI) at Resolute Bay, which indicates the lack of polar cap heating in the model. Based on these results, we conclude that the polar cap may be essential to energy input and dissipation in the MIT system and more improvements are needed to capture the strong heating in models.