High-resolution study of the relationship between the Region 2 equatorward boundary and soft electron precipitation

The nightside Region 2 (R2) Birkeland current system is associated with magnetospheric dynamics occurring close to the inner magnetosphere. The current carriers for this system have been studied extensively at higher energies; in this study we investigate the potential role of electrons in the less-studied suprathermal (sub-keV) range. The Enhanced Polar Outflow Probe (e-POP) instrument suite consists of eight plasma instruments including the Suprathermal Electron Imager (SEI) and the magnetic field instrument. (MGF) The SEI records two-dimensional energy-angle images of electron distribution for energies up to 350 eV at a rate of 100 images per second. The MGF samples the magnetic field at a sampling rate of 160 times per second with a resolution of 0.0625 nT. The electron precipitation over the region of 45-80 magnetic latitude during different geomagnetic conditions was examined based on data from two years of ePOP data and a total of 50 traversals of the R2 equatorward boundary were identified. We present a multi-instrument statistical study to determine the relationship between this boundary and soft electron (< 1 keV) precipitation as a function of magnetic local time and magnetic latitude.