MAXIMUM ALTITUDE PENETRATION OF ATMOSPHERIC GRAVITY-WAVES OBSERVED DURING ALOHA-93

Atmospheric Gravity Waves (AGWs) are subject to altitude propagation l imits which are governed by the diffusion processes. Diffusion times a nd scales which exceed the wave period and wavelength define the limit ing domain for AGWs. An expression is presented which defines the uppe r altitude limit to which AGWs can propagate given vertical diffusion constraints of the atmosphere. Airglow, lidar, and radar measurements are combined to characterize the intrinsic AGW parameters in the 80-10 5 km altitude region. A subset of AGWs (17) observed by airglow imager s during the ALOHA-93 were made when simultaneous wind measurements we re available and intrinsic wave parameters were calculated. The limiti ng altitude of propagation for these measured monochromatic waves is c alculated to range from 110-150 km (with a mean limiting altitude of 1 30 km). The altitude limit is for waves with necessarily lower short v ertical wavelengths and longer intrinsic periods. This observation is important for a large number of issues including energetic considerati ons regarding thermospheric heating in models which consider upward pr opagating AGWs (and energy flux) of tropospheric origin. This limited data base should be expanded for statistical significance in future wo rk.