The Role of Substorm Injections on the Extreme Geo-Effectiveness
Observed in the Inner Magnetosphere on the 8 September 2017 Geomagnetic
Storm
Abstract
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.