Abstract

In this study, we present ionospheric observations of field-aligned currents from AMPERE and the ESA Swarm A satellite, in conjunction with high-resolution thermospheric density measurements from accelerometers on board Swarm C and GRACE-FO, for the 3rd and 4th February 2022 geomagnetic storms that led to the loss of 38 Starlink internet satellites. We study the global storm time response of the thermospheric density enhancements, including their growth, decay, and latitudinal distribution. We find that the thermospheric density enhances globally in response to high-latitude energy input from the magnetosphere-solar wind system, and takes at least a full day to recover to pre-storm density levels. We also find that the greatest density perturbations occur at polar latitudes consistent with the magnetosphere-ionosphere dayside cusp, and that there appeared to be a saturation of the thermospheric density during the geomagnetic storm on the 4th. Our results highlight the critical importance of high-latitude ionospheric observations when diagnosing potentially hazardous conditions for low-Earth-orbit satellites.