Global Capabilities of Modeling Auroral Precipitation - Characterizing Contributors and Drivers

While auroral particle precipitation is a vital component in predictive studies of magnetosphere - ionosphere coupling, an accurate estimation of precipitation is challenging in global magnetohydrodynamic (MHD) models. Several studies (e.g. Wiltberger et al. 2009, Gilson et al. 2012, Zhang et al. 2015, Yu et al. 2016) have used adiabatic kinetic theory to derive individual sources of precipitation from MHD quantities. However, the driving factors behind these sources remain understudied. In this work, we investigate the impact of individual sources of precipitation & their drivers on modeled variables, with respect to variations in global conditions such as geomagnetic driving, asymmetries, distribution functions, spatial grid resolution, and physical components (e.g. ring current models).

To undertake this study, the novel MAGNetosphere - Ionosphere - Thermosphere (MAGNIT) auroral conductance model has been used to compute diffuse and monoenergetic electron and ion precipitation. MAGNIT is integrated into the Space Weather Modeling Framework to couple dynamically with the BATS-R-US MHD model, the Rice Convection Model (RCM) of the ring current & the Ridley Ionosphere Model (RIM) to simulate the April 2010 "Galaxy15" Event. The model is used with three grid configurations: the setup currently employed by NOAA's Space Weather Prediction Center and two additional configurations that decrease the minimum grid size from 1/4 RE to 1/8 & 1/16 RE. In addition, the simulation is driven with and without the dynamic coupling with RCM to study the impact of the ring current's pressure correction on precipitation. Using this model setup with a (a) Maxwellian, and (b) Kappa (k = 5) distribution, the aforementioned precipitation sources are progressively applied and compared against existing conductance models in RIM, the OVATION Prime Model and DMSP SSUSI passes of both the northern and southern poles. Further, data-model comparisons against AMPERE Field-Aligned Currents, SuperDARN convection patterns, ISRs, geomagnetic indices & magnetometer measurements are shown. Modeled results show remarkable progress in capturing mesoscale features through high-resolution MHD simulations. Results also indicate a dominant impact of ring current on the strength and morphology of the precipitation pattern.