Geophysical Research Letters
American Geophysical Union
Atmospheric Gravity Waves (AGWs) are subject to altitude propagation limits which are governed by the diffusion processes. Diffusion times and scales which exceed the wave period and wavelength define the limiting domain for AGWs. An expression is presented which defines the upper 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 80–105 km altitude region. A subset of AGWs (17) observed by airglow imagers during the ALOHA‐93 were made when simultaneous wind measurements were available and intrinsic wave parameters were calculated. The limiting altitude of propagation for these measured monochromatic waves is calculated to range from 110–150 km (with a mean limiting altitude of 130 km). The altitude limit is necessarily lower for waves with short vertical wavelengths and longer intrinsic periods. This observation is important for a large number of issues including energetic considerations regarding thermospheric heating in models which consider upward propagating AGWs (and energy flux) of tropospheric origin. This limited data base should be expanded for statistical significance in future work.
Swenson, G.R., C.S. Gardner and M.J. Taylor, Maximum penetration of atmospheric gravity waves observed during ALOHA-93, Geophys. Res. Lett., 22, 2857, 1995.