Ring Current Decay of Moderate Storms at Solar Maximum: Global Modeling Using Superposed Epoch Upstream Conditions

This study is an extension of our previous high-performance storm simulation with the coupled BATS-R-US (Block Adaptive Tree Solar-wind Roe-type Upwind Scheme) global magnetohydrodynamics (MHD) model, Rice Convection Model (RCM), and Ridley Ionosphere Model (RIM). In this work, the superposed epoch recovery phase of 34 moderate storms at solar maximum (July, 1999 -- June, 2002) is simulated for averaged upstream solar wind conditions with the standalone RCM and also with the coupled codes. Superposed epoch averages of Dst, Sym-H, and the Los Alamos Magnetospheric Plasma Analyzer (MPA) observations at geosynchronous orbit are used to validate the modeling results. In addition, parameters in the standalone RCM and the coupled codes are adjusted to systematically study the effects of interchange instability, charge exchange rate, particle drift intensity, and particle energy levels on the ring current decay. Computer experiments will also explore how magnetic field changes and time-dependent plasma-sheet density affect the recovery phase.