Ring Current Influence on Ionospheric Morpology using HEIDI/GITM

Abstract:

A longstanding challenge for ionosphere-thermosphere models has been the inclusion of accurate and self-consistent electrodynamic inputs in the auroral zone. Phenomenon such as penetration electric fields (PEFs), storm enhanced densities (SEDs), and sub-auroral polarization streams (SAPS) are inextricably linked to the coupled magnetosphere-ionosphere-thermosphere system. To address this, the global ionosphere-thermosphere model (GITM) has been coupled to the hot electron ion drift integrator (HEIDI) model of the inner magnetosphere and ring current. However, since the electrodynamic system is strongly dependent on the ionospheric conductance, HEIDI was first updated to include a self-consistent auroral model. HEIDI now calculates the total energy flux and average energy in the auroral zone by calculating the flux of electrons in the loss cone at each time-step. These are used with the Robinson formula to derive the Hall and Pedersen conductances as well as in the potential solver, along with the field-aligned currents, to generate an electric potential pattern which is subsequently used to advect the particles in HEIDI. The resulting aurora and potentials are then used to drive GITM in a one-way coupling. HEIDI and GITM were run for multiple storms using this configuration, and a number of phenomena were investigated, such as PEFs, SEDs and SAPS, as well as their influence on the thermospheric temperature, density and wind structure. Simulations of real storms were compared to incoherent scatter radar, GPS TEC, and satellite data to understand the differences between the old and new model results.