Midlatitude F-region neutral winds and temperatures during the priority regular world day 14 August 1980

Abstract

Midlatitude F-region neutral winds and temperatures determined from Fabry-Perot interferometer measurements of the doppler shifts and widths of nightglow 630.0 nm line profiles are presented for the priority regular world day 14 August 1980. They exhibit, in many respects, the observed behavior for other summer, geomagnetically quiet nights at solar maximum. The neutral temperature decreases from ∼ 1500°K after sunset (21 h LT) to a minimum of ~ 1200°K before dawn (05 h LT), except to the north of the observatory. The zonal winds are eastward at sunset at ∼ 50 m/sec, decrease to zero at ∼ 02 h LT and are westward just before dawn. The meridional winds are zero just after sunset and reach a maximum equatorward value of ∼ 50–70 m/sec at local midnight but do not decrease as predicted; instead, they remain at roughly these values towards dawn. The NCAR thermospheric general circulation model (TGCM) is used to predict the global upper atmospheric temperature and circulation patterns for this world day. The model predictions agree with the measured neutral temperatures and exhibit qualitative similarities to the measured neutral winds. It is concluded that inclusion in the model of ion drift at midlatitudes should improve the agreement with observations.