Tornado-generated Ionospheric Disturbances: Comparison of GITM-R simulations with GNSS

Geophysical events such as earthquakes, tsunamis, and tornados can create disturbances in the ionosphere-thermosphere (IT) system by propagation of the developed acoustic-gravity waves (AGWs). Large convective storms in the lower atmosphere are known to develop atmospheric disturbances that can be observed in the ionosphere by ground based Global Navigation Satellite Systems (GNSS) receivers [1]. The Easter 2020 tornados in Mississippi appeared to produce concentric Meso-scale traveling ionospheric disturbances (TIDs) that propagated beyond the Canadian border. The focus of this study is to simulate ionospheric Total Electron Content (TEC) variations induced by tornado events using a global circulation model and to subsequently compare the simulated results to the Easter 2020 event GNSS data. The tornados atmospheric influence causes relatively localized perturbations that then propagate radially outward. Simulations using the Global Ionosphere-Thermosphere Model with local mesh refinement (GITM-R) are performed to capture mesoscale subtleties in the regions near the tornado [2,3]. GITM's lower boundary is at ~100 km altitude, thus an analytical AGW propagation model is used in conjunction with an analytic tornado vortex model to specify GITM's lower boundary. The simulated TEC variations are compared to GNSS data to demonstrate GITM's ability to resolve mesoscale acoustic-gravity wave signals induced by tornados.