Modeling inner magnetospheric electric fields: Latest self-consistent results

This paper presents some of the latest results of self-consistent numerical modeling of large-scale inner-magnetospheric electric fields obtained with the Rice Convection Model (RCM). The RCM treats plasma drifts, electric fields, and currents in the inner magnetosphere self-consistently in the quasi-static (slow-flow) approximation under the assumption of isotropic pitch-angle distribution. Event simulations of the magnetic storm of March 31, 2001 are used with two newly available RCM input models: an empirical model of the storm-time magnetospheric magnetic field, and an empirical model of the plasma sheet. Results show that the effect of severe distortion of the magnetic field during very large magnetic storms improves the ability of the RCM to predict the location of Sub-Auroral Polarization Stream (SAPS) events, although there is not perfect agreement with observations. Weakening of shielding by region-2 Birkeland currents during times of severe magnetic field inflation also improves comparison of the RCM-computed plasmapause location with data. Results of simulations with plasma boundary sources varying in response to measured solar wind inputs show that the plasma sheet may become interchange unstable under certain geomagnetic conditions.