WINDII measurements of nightglow enhancements in the South Atlantic magnetic anomaly zone

Enhancements of the O(D-1) 630 nm and O(S-1) 558 nm volume emission rates w ere detected by WINDII, the Wind Imaging Interferometer on board the Upper Atmosphere Research Satellite, UARS, as its limb-locked fields of view cros sed the South Atlantic magnetic anomaly zone during periods of high geomagn etic activity The enhancement attributed to electron precipitation is 20 R for the 630 nm red line and 3 R for the 558 nm green line, less than the na tural variability of these nightglow emissions as seen from below. Neverthe less? statistical tests indicate with 95% confidence that the enhancements are significantly distinguishable from the natural variability. The red enh ancement lies west of the green because eastward drifting trapped electrons move toward lower mirror altitudes in this region. These enhancements are energetically consistent with earlier measurements of electron fluxes in th is region; we estimate the total precipitation energy deposition rate at a few megawatts.