OpenGGCM-RCM modeling of SAPS events

Abstract:

Sub-Auroral Polarization Streams (SAPS), also known as Sub-Auroral Ion Drifts (SAIDs), are fast westward flows in the ionosphere that occur at latitudes lower than auroral precipitation, and well separated from the high-latitude convection pattern. Although SAPS were first observed in the ionosphere, they can also be seen in the magnetosphere and are believed to be driven by a combination of region-2 currents and low ionospheric conductance. SAPS are thus governed both by magnetosphere and ionosphere processes and require self-consistently coupled models of the outer magnetosphere, the inner magnetosphere and the ring current, and the ionosphere-thermosphere system. Here, we present first results from the OpenGGCM-RCM coupled model, which includes all of the required physical processes and feedbacks. In particular, the ionospheric conductance is computed self-consistently from both magnetosphere electron precipitation, solar ionization, and ionospheric chemistry within the fully dynamical CTIM sub model of OpenGGCM. Furthermore, CTIM includes the recombination feedback of streaming ions. We focus on the GEM-CEDAR storm events of 2013-03-17, 2011-04-27, 2012-05-07, and 2012-09-02. We show that the coupled model produces SAPS that compare well with data in terms of location, extent, and magnitude. By modifying the conductances in the code we evaluate the potential positive feedback process of the ionospheric conductance on SAPS.