A seasonal study of mesospheric temperatures and emission intensities at Adelaide and Alice Springs

Aerospace imagers operating at Alice Springs (23°42'S, 133°53'E) and Adelaide (34°55'S, 138°36'E) have collected more than 4-year of OH and O₂ atmospheric emission data. Images taken over the course of each moonless night at 5-min intervals were used to determine OH Meinel (6, 2) and O₂ Atmospheric (0, 1) band emission intensities and temperatures, as well as atmospheric gravity wave parameters. The NCAR general circulation model TIME-GCM was run for years 2002-2005 for comparison with these data. The data presented here show the interannual variability of OH and O2A emissions at two sites, Alice Springs and Adelaide, over a 4-a period. It was found that the TIME-GCM successfully reproduces many observed features of the data, including equinoctial maxima associated with the diurnal tide, a 6-h phase shift between OH temperature and intensity maxima, and springtime OH intensity enhancements at Alice Springs. However, the model tends to underestimate the depth of the summertime temperature minimum at both sites, possibly due to inadequate specification of the seasonal variation of gravity waves in the model. The model does, however, successfully describe many of the mesospheric changes observed during the 2002 stratospheric warming event.