The control of background conditions on LSTAD/LSTID propagation

Abstract:

Past studies have been focused on exploring the possible generation and propagation mechanisms of the large scale traveling ionospheric/thermospheric disturbances (LSTIDs/LSTADs) generated at high latitudes by auroral processes. However, how the background conditions of the ionosphere and thermosphere impact their equatorward propagation is not well understood. This study is specifically focused on exploring the control of background conditions on the equatorward propagation of the LSTIDs/LSTADs generated at high latitudes. We employ a two-way coupled ionosphere-thermosphere model, developed by combining WACCM-X (Whole Atmosphere Community Climate Model, Extended version) with the three-dimensional ionospheric model SAMI3 (SAMI is Another Model of Ionosphere), to simulate LSTADs and LSTIDs. The background ionosphere/thermosphere conditions (such as winds, temperature, density, etc.) in the model are modified by changing the season, time of day, and solar forcing in order to assess the control of the background conditions on the propagation LSTADs/LSTIDs. We perform a variety of simulations with differing background conditions, but keeping high-latitude drivers the same that generate auroral LSTADs/LSTIDs. By comparing a range of simulations, we isolate the effect of background conditions on the long-distance propagation of LSTADs/LSTIDs.