A modeling study on the responses of the Mesosphere and Lower Thermosphere (MLT) temperature to the initial and main phases of geomagnetic storms at high latitudes

In the mesosphere and lower thermosphere (MLT), however, the causes of storm-time temperature changes at high latitudes are still elusive. Here, we elucidate the nature and mechanisms of MLT temperature variations at high latitudes during the 10 September 2005 storm by diagnostically analyzing the MLT thermodynamics in the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM) simulations.

In the storm's initial and main phases, the MLT temperature decreases at 0:00 local time (LT)-12:00 LT, but increases in the 12:00 LT-24:00 LT sector at high latitudes. Afterward, the temperature decrease disappears and temperature increase occurs at all local times in the high latitudes. Adiabatic heating/cooling and vertical advection associated with vertical winds are the main drivers of high-latitude temperature changes in the entire altitude range of the MLT region.