Relative Contributions of Ion Convection and Particle Precipitation to Exciting Large-Scale Traveling Atmospheric and Ionospheric Disturbances

During geomagnetically active times, the enhanced ion convection and particle precipitation at high latitudes cause substantial disturbances in the ionosphere and thermosphere. Large-scale traveling ionospheric disturbances (LSTIDs) were identified from Global Positioning System (GPS) total electron content (TEC) measurements from 06:30 to 08:30 UT on 26 March 2014 as a result of southward turning of the interplanetary magnetic field (IMF) Bz and enhanced particle precipitation during a substorm. The comparison of LSTIDs from the global ionosphere-thermosphere model (GITM) simulations with GPS TEC measurements shows a general agreement. Further theoretical analyses with GITM were conducted to sperate the influence of ion convection and particle precipitation on the total Joule heating as well as on the resulting large-scale traveling atmospheric disturbances (LSTADs) and LSTIDs. It was found that ion convection and particle precipitation have comparable contributions to the total Joule heating, although the changes of height-integrated Joule heating due to these two forcing terms may display different distributions. In addition, the magnitudes of neutral density and TEC perturbations due to these two forcing terms were found to be comparable. Using the total energy flux versus time derived from all-sky imager measurements for this event to drive GITM improves the data-model comparison of LSTIDs. However, data-model discrepancies still exist in the timing of LSTIDs and the magnitude of TEC perturbations, which calls for further investigation and realistic event-specific specifications.