The effect of ring current electron scattering rates on magnetosphere-ionosphere coupling

This simulation study investigated the electrodynamic impact of varying descriptions of the diffuse aurora on the magnetosphere-ionosphere (M-I) system. Pitch angle diffusion caused by waves in the inner magnetosphere is the primary source term for the diffuse aurora, especially during storm time. The magnetic local time (MLT) and storm-dependent electrodynamic impacts of the diffuse aurora were analyzed using a comparison between a new self-consistent version of the Hot Electron Ion Drift Integrator with varying electron scattering rates and real geomagnetic storm events. The results were compared with Dst and hemispheric power indices, as well as auroral electron flux and cross-track plasma velocity observations. It was found that changing the maximum lifetime of electrons in the ring current by 2\textendash6\ h can alter electric fields in the nightside ionosphere by up to 26\%. The lifetime also strongly influenced the location of the aurora, but the model generally produced aurora equatorward of observations.