Auroral zone thermospheric dynamics: 1. Averages

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Abstract
Forty‐four nights of thermospheric neutral wind and temperature measurements were obtained with a ground‐based Fabry‐Perot spectrometer at College, Alaska (65° invariant latitude), mostly during high to moderate levels of solar activity. The spectrometer scanned the O I 15,867 K (6300 Å) emission line yielding line profile measurements that originate from an altitude range between 170 and 280 km. The observed average wind direction is to the northwest in the early evening, changing to the south near midnight and then to the southeast in the morning. The overall wind pattern generally persists, but the wind speed increases with increasing geomagnetic activity. A change in the zonal wind direction occurs earlier in magnetic local time with increasing magnetic activity. The meridional wind pattern also shifts equatorward with the auroral oval during increasing magnetic activity. Consequently, the average wind pattern in the north during low geomagnetic activity is rather similar to the moderate activity average in the south, and the moderate geomagnetic activity average wind pattern in the north is similar to the high geomagnetic activity average in the south. The observed average thermospheric temperature is found to be governed by geomagnetic activity and the previous day's 10.7‐cm solar flux.

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