Space Physics Seminar fall-2015

The terrestrial ionosphere driven from above and from below: a modeling experience

The terrestrial ionosphere represents an interface between the magnetosphere and lower atmosphere. Conditions in the ionosphere depend on both the space weather from above and the neutral atmospheric dynamics from below. We perform numerical simulations of the ionosphere and look into the total electron content (TEC) disturbances induced by 1) geomagnetic storms 2) atmospheric gravity waves. For geomagnetic storms, we make TEC predictions with the Global Ionosphere-Thermosphere Model (GITM) to explore the feasibility of ionospheric forecasts with the current generation of physics-based models. A TEC metric has been developed to quantify forecasted storm-time TEC disturbances. The simulation results are compared with Global Positioning System satellite observations. For atmospheric gravity waves, we focus on upward propagating waves generated by tsunamis, which could cause traveling TEC perturbations in the ionosphere. To capture this process, we have implemented tsunami-generated gravity waves into GITM to construct a three-dimensional physics-based model Wave Perturbation-GITM. The model has been shown to reproduce the ionospheric signatures of a major tsunami event.