Temperatures and tides in the high latitude mesopause region as observed in the OH night airglow emissions

The OH (6-2) band night airglow emissions have been observed from two sites at 60 and 70°N, respectively, in Norway during the December–April periods 1985–1986 and 1986–1987. Variations in rotational temperatures at ~90 km on time scales from tens of minutes to days show similar patterns as at 80°N. The semi-diurnal tide is dominant with average peak to peak amplitudes of ~5 K over the observing periods. There is a negligible difference in average tidal amplitude at 60 and 70°N. The phase of the tide is changing slowly through the December–February period. The mid-winter to early spring average temperatures are ~10 K higher than predicted by the CIRA 1972 90 km model atmosphere for the respective sites.