Abstract
Atomic Hydrogen (H) is the most abundant constituent of the terrestrial
exosphere. Its charge exchange interaction with ring current ions (H+
and O+) serves to dissipate magnetospheric energy during geomagnetic
storms, resulting in the generation of energetic neutral atoms (ENAs).
Determination of ring current ion distributions through modeling depends
critically on the specification of the exospheric H density
distribution. Furthermore, theoretical studies have demonstrated that
ring current recovery rate after the storm onset directly correlates
with the H density. Although measurements of H airglow emission at
altitudes [3,6] Re exhibit storm-time variations, the H density
distributions used in ring current modeling are typically assumed to be
temporally static during storms. In this presentation, we will describe
the temporal and spatial evolution of ring current ion densities in
response to a realistically dynamic exospheric H density distribution
using the Comprehensive Inner Magnetosphere-Ionosphere Model (CIMI). The
exospheric densities used as input to the model are fully data-driven,
derived as global, 3D, and time-dependent tomographic reconstructions of
H emission data acquired from Lyman-alpha detectors onboard the NASA
TWINS satellites during the geomagnetic storm that occurred on March 17,
2013. We will examine modeled ring current recovery rates using both
dynamic and static reconstructions and evaluate the impact of realistic
storm-time exospheric variability on the simulations.