Modeling the Severe Storm on St. Patrick's Day 2015

A severe geomagnetic storm struck the magnetosphere on the St. Patrick's Day of 2015. The Dst index reached a minimum of -223 nT. Dazzling aurora were seen as far south as Oregon and Illinois. To understand the origins of this extreme event, we simulated the dynamics of energetic ions and electrons using the Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. We reproduced a number of observable signatures, such as extended ionosphere precipitation, multiple-peaks ring current seen by TWINS spacecraft, and relativistic electron enhancement during recovery seen by geosynchronous and Van Allen Probes satellites. We have performed several model runs with different input parameters and model setup to identify the physical processes responsible for the distinct features of this event.