Airglow imager observations of atmospheric gravity waves at Alice Springs and Adelaide, Australia during the Darwin Area Wave Experiment (DAWEX)

Copyright © 2004 by the American Geophysical Union.The Darwin Area Wave Experiment occurred in Australia from October to December 2001. An objective was to characterize the atmospheric gravity wave field produced from intense convective activity that is routinely observed around Darwin during November and December. Two airglow imagers were sited at Adelaide and at Alice Springs, each located over 1000 km south of Darwin. Waves were observed at the mesopause region propagating predominantly toward the southeast, with some going to the northwest but with none observed going from east to west. The lack of waves propagating toward the west suggests some wind filtering mechanism below 80 km altitude. Waves observed over Alice Springs were analyzed in detail on three nights. On 16 November they were seen propagating toward the northwest. It is proposed that they were generated by dynamical events associated with a cutoff low-pressure system present over southwest Australia. On 17 and 19 November the observations are consistent with wave generation by convective activity present in the Darwin area. Thus as proposed by Walterscheid et al. [1999] and Hecht et al. [2001a] , the ducting of waves from distant sources is shown to be a viable explanation for the quasi-monochromatic waves frequently observed in airglow observations. Walterscheid et al. [1999] suggested that ducting of waves from the extensive region of deep cumulus convection over northern Australia explained the strong poleward directionality seen in the summer months. The present study suggests that propagation from northern Australia is selective, and ducted waves from this region may not be the primary source of waves over Adelaide when convection is occurring over central Australia.Hecht, J. H., S. Kovalam, P. T. May, G. Mills, R. A. Vincent, R. L. Walterscheid, and J. Woith