The investigators will use an airglow imaging instrument to measure atmospheric gravity waves with horizontal wavelengths less than 100 km. They will place a new infrared airglow imager with high sensitivity at the Starfire Optical site in New Mexico. The imager will be used in conjunction with other Starfire instrumentation to investigate the breakdown of gravity waves as well as the momentum flux deposited by acoustic gravity waves, which are believed to be thermally ducted from source regions thousands of kilometers away. The investigators will also analyze airglow imaging data from northern Germany, comparing the results with similar data obtained from Illinois. At the German site, mesopause temperatures can be less than 1250 K, while in Illinois the temperatures are usually greater than 170K. In 1999, the imager will be deployed in Australia for two years, a period of time long enough to allow a better characterization of gravity wave climatology in the southern hemisphere at mid-latitude.
