Latitudinal variations in the neutral atmospheric density

Abstract

In-situ atmospheric density measurements from the Explorer 32 density gauges for the time period May through October 1966 reveal latitudinal density structure in the neutral thermosphere during geomagnetically undisturbed times. At altitudes -between 400 and 700 km the densities at northern geographic latitudes ( > 55") a r e at least 1.5 times the equatorial densities during the daytime, and greater a t night. The northern auroral zone atmospheric densities have been observed to be as much as a factor of five greater than the equatorial densities at altitudes between 450 and 600 kilometers, even on geomagnetically quiet days. These results suggest that auroral zone and high latitude heating is a permanent feature of the summer thermosphere.