Trends of airglow imager observations near Adelaide, Australia

From April, 1995 to January, 1996 a nightglow imager and an airglow photometer were colocated near Adelaide, Australia. The data obtained on more than 50 clear nights revealed seasonal changes in the airglow intensities and temperatures as well as in the gravity wave activity. These temperature data are the first seasonal results from the mid-latitude southern hemisphere mesopause region. The OH Meinel band was observed to have a rotational temperature that was warmer than the O2 Atmospheric band in the winter. There were also summer solstice maxima and winter solstice minima in the O2 Atmospheric band and OI(557.7' airglow intensities. The gravity wave activity, seen in the 50 to 80 km horizontal wavelength waves, was generally greatest in the OH Meinel layer and showed a semiannual variation with a strong summer solstice maximum. The relationship between gravity wave activity and airglow intensities disagrees somewhat with models. Compared to previous studies, the data suggest that there may be a difference in the seasonal variability of short and long period gravity waves.