Simulations of Energetic Particle Dynamics in the Coupled Inner Magnetosphere During Double-dip Storms

Abstract:

We use a combination of several physics-based models as well as analysis of space-borne and ground-based observations to study the coupled magnetosphere-ionosphere system during the 7-10 September 2017 double-dip storm. A ring current-atmosphere interactions model with self-consistent magnetic field and (recently added) self-consistent electric field (RAM-SCBE) is used to simulate the injection of ions and electrons from the plasma sheet into the inner magnetosphere and their precipitation to the ionosphere. The boundary conditions for RAM-SCBE at geosynchronous orbit are obtained with a large-scale particle tracing model that tracks different ion species in global electric and magnetic fields. The results are compared with RAM-SCBE simulations driven by geosynchronous observations and ion composition specified after statistical studies. We investigate whether the model can reproduce the large enhancements of ring current H⁺ and O⁺ fluxes observed by Van Allen Probes and Arase satellite during the storm main phase. In addition, intense electromagnetic ion cyclotron (EMIC) waves were recorded during this storm period both in situ and on ground but with different spatial and temporal dependence. The effects from ion composition variability on ring current dynamics and EMIC wave generation are discussed.