CEDAR: Studies of Trapped, High Frequency Acoustic-Gravity Waves near the Mesopause

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Two sets of related measurements are proposed that build upon the PI's previous work in studying small-scale, fast atmospheric acoustic-gravity waves. During the past year and a half, a new Aerospace built infrared (1.5 - 1.7 um wavelength) airglow imager has operated at the Starfire Optical Site in New Mexico. It is now proposed to move this new fast imager to Maui to take advantage of the placement of the lidar at that site. Previous work has shown the existence of acoustic waves in time series spectra from a Hawaii based IR spectrograph. The emphasis here will be on studying the as yet poorly explored short period ( 5 minute observed period) acoustic-gravity waves, and the very small scale (a few km horizontal wavelength) instabilities. These results will complement the studies of the longer period gravity waves undertaken by other investigators using their imaging instruments at Maui.Further, there is strong experimental evidence that small-scale waves seen in airglow images are ducted from a source region in the troposphere that could be located a thousand kilometers or more from the observation site. Previous data suggest that the waves seen over Adelaide, Australia around summer solstice are ducted from a source region of strong convective activity well to the north perhaps as far away as the north coast. The PIs propose work in wave sources and propagation enabled by a unique capability for imaging and by the fortuitous nature of the climate and topography of Australia. Specifically, they propose to obtain data from two airglow imagers; one located at Adelaide and another at Alice Springs, Australia about 1500 km to the north. These will be part of a four imager chain, to begin operating in late 2001, that extends from the northern to the southern coast of Australia as part of the Darwin Wave Experiment (DAWEX) in late 2001.