Cristian Ferradas

and 7 more

The event of 8 September 2017 was characterized by the effects of the arrival of two interplanetary coronal mass ejections on September 6th and 7th and a resultant geomagnetic storm. This storm event has been widely studied due to its extreme geo-effectiveness in the global geospace. In the inner magnetosphere, the effects included a distinct intensification of the ring current and a severely eroded plasmasphere. However, little attention has been paid to the role that the observed substorm injections played on the storm-time ring current. Starting at 1209 UT on September 8th, multiple substorm onsets occurred spreading over a wide magnetic local time range on the dawn side. Multiple substorm injections were observed simultaneously at geosynchronous orbit by the Los Alamos National Laboratory satellites and the Geostationary Operational Environmental Satellites, and by both the Exploration of energization and Radiation in Geospace/Arase and the Van Allen Probes missions deep in the inner magnetosphere. Subsequent buildup of the ring current was observed. In this study, we will investigate the role of the substorm injections on the extreme ring current response by numerical simulations with the physics-based Comprehensive Inner Magnetosphere-Ionosphere model using the geosynchronous data as boundary conditions to the model. Since the ring current has a strong influence on the inner magnetospheric dynamics, we also consider its impacts on the dynamics of the electric field and the plasmasphere. Furthermore, this study addresses the critical need to include substorms in evaluating the geo-effectiveness of geomagnetic storms.

Gonzalo Cucho-Padin

and 3 more

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.

Nat Gopalswamy

and 6 more