Modeling of DMSP Surface Charging Events

Measured spectra from a selection of Defense Meteorological Satellite Program-observed charging events were analyzed, with the goal of improving modeling of auroral charging events. Each data set was examined for correlations between the chassis potential and the measured fluxes. Chassis potential was found to be correlated with both the median electron energy and the net electron flux. The background plasma density cannot be determined directly from the measured spectra due to distortions from charging and the variation in sensitivity with incident particle energy across each energy channel. Simulations using time-varying spectra show that the chassis potential responds to even fairly subtle environment changes on a millisecond time scale. As the environment measurements take 1 s per spectrum, the chassis potential can easily be changing, either steadily or erratically, during that time. Once the limitations of the measurements are accounted for, the calculated chassis potential agrees with the measured potential through the modeled charging events.