A statistical study of the subauroral electron temperature enhancement using Dynamics Explorer 2 Langmuir probe observations

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Abstract
A statistical study of the F region subauroral electron temperature enhancement was undertaken using data from the Langmuir probe experiment on the DE‐2 satellite for 488 passes through the plasmapause region during the periods September 16–30 and October 17–26, 1981. Satellite passes covered the altitude range 350–1000 km and two local solar time intervals: 8–10 and 21–23 hours. The subauroral electron temperature enhancement has an altitude dependent occurrence frequency with strong day‐night differences. The position (invariant latitude) of the subauroral electron temperature enhancement varies with magnetic activity in much the same manner as the equatorial plasmapause signatures discussed in the literature. The magnitude of the electron temperature peak increases statistically with increasing magnetic activity about 8 K per 1 γ decrease in Dst for altitudes below 600 km and 23 K per 1 γ decrease in Dst for altitudes between 600 and 1000 km on the nightside. There is a positive gradient of peak electron temperature with height on the nightside that increases statistically from 1.4 K/km (Dst > −40) to 3 K/km (Dst < −40) reflecting enhanced heat flow from high altitudes. The statistical response of the magnitude and location of the subauroral electron temperature peak to magnetic activity can account for the observed SAR arc occurrence statistics.