Poynting Flux From DMSP in Auroral Boundary Coordinates

We use magnetic perturbations and ion drift velocity from the Defense Meteorology Satellite Program (DMSP)  F15, F16, F17 and F18 spacecraft to compute the downward directed DC Poynting Flux at 850 km for several years under varying solar cycle conditions. To reduce the bias from instrument artifacts in the Poynting flux, we use baseline-corrected “Level-2” magnetometer data (Kilcommons et al. 2017) and filter the Ion Drift Meter (IDM) and Retarding Potential Analyzer (RPA) measurements using the University of Texas, Dallas (UTD) quality flags. Additionally, we apply a baseline correction to the ion drift measurements to reduce bias.
To investigate partitioning of energy deposition between the auroral region and the polar cap, we use the DMSP electron precipitation auroral boundary detection algorithm (Kilcommons et al., 2017) to divide each DMSP orbit into polar cap, auroral and subauroral regions, and bin the corresponding Poynting flux both in standard magnetic coordinates and also relative to these boundaries.
We show statistical maps of ion convection velocity, average Poynting Flux strength, likelihood of strong flux, and other electrodynamic parameters both in magnetic and auroral boundary coordinates. We particularly highlight the strong influence of the sign of IMF By on the location of Poynting flux electromagnetic energy deposition.