Magnetospheric Signatures of STEVE: Implications for the Magnetospheric Energy Source and Interhemispheric Conjugacy

Abstract

We present three STEVE (strong thermal emission velocity enhancement) events in conjunction with Time History of Events and Macroscale Interactions (THEMIS) in the magnetosphere and Defense Meteorological Satellite Program (DMSP) and Swarm in the ionosphere, for determining equatorial and interhemispheric signatures of the STEVE purple/mauve arc and picket fence. Both types of STEVE emissions are associated with subauroral ion drifts (SAID), electron heating, and plasma waves. The magnetosphere observations show structured electrons and flows and waves (likely kinetic Alfven, magnetosonic, or lower-hybrid waves) just outside the plasmasphere. Interestingly, the event with the picket fence had a >~1 keV electron structure detached from the electron plasma sheet, upward field-aligned currents (FACs), and ultraviolet emissions in the conjugate hemisphere, while the event with only the mauve arc did not have precipitation or ultraviolet emission. We suggest that the electron precipitation drives the picket fence, and heating drives the mauve as thermal emission.