Abstract
Despite significant developments in global modeling, the determination
of ionospheric conductance in the auroral region remains a challenge in
the space science community. With advances in adiabatic kinetic theory
and numerical couplings between global magnetohydrodynamic models and
ring current models, the dynamic prediction of individual sources of
auroral conductance have improved significantly. However, the individual
impact of these sources on the total conductance and ionospheric
electrodynamics remains understudied. In this study, we have
investigated individual contributions from four types of auroral
precipitation - electron & ion diffuse, monoenergetic & Alfven
wave-driven - on ionospheric electrodynamics using a novel modeling
setup. The setup encompasses recent developments within the University
of Michigan’s Space Weather Modeling Framework (SWMF), specifically
through the use of the MAGNetosphere - Ionosphere - Thermosphere auroral
precipitation model and dynamic two-way coupling with the Global
Ionosphere-Thermosphere Model. This modeling setup replaces the
empirical idealizations traditionally used to estimate conductance in
SWMF, with a physics-based approach capable of resolving 3-D
high-resolution mesoscale features in the ionosphere-thermosphere
system. Using this setup, we have simulated an idealized case of
southward Bz 5nT & the April 5-7 “Galaxy15” Event. Contributions from
each source of precipitation are compared against the OVATION Prime
Model, while auroral patterns and hemispheric power during Galaxy15 are
compared against observations from DMSP SSUSI and the AE-based FTA
model. Additionally, comparison of field aligned currents (FACs) and
potential patterns are also conducted against AMPERE, SuperDARN & AMIE
estimations. Progressively applying conductance sources, we find that
diffuse contributions from ions and electrons provide
~75% of the total energy flux and Hall conductance in
the auroral region. Despite this, we find that Region 2 FACs increase by
~11% & cross-polar potential reduces by
~8.5% with the addition of monoenergetic and broadband
sources, compared to <1% change in potential for diffuse
additions to the conductance. Results also indicate a dominant impact of
ring current on the strength and morphology of the precipitation
pattern.