JP5.22
The sensitivity of above-cloud gravity wave breaking and turbulence to background flow conditions
Todd P. Lane, NCAR, Boulder, CO; and R. D. Sharman
Convective clouds generate gravity waves that can propagate vertically and / or horizontally away from the cloud. Such waves can influence the momentum budget of the middle atmosphere, and can contribute to turbulence and mixing in regions of wave instability and breakdown. This turbulence and mixing is important for aviation applications, and may contribute to chemical transport processes. Recent studies have shown that the horizontal scales of gravity waves generated by convection are shorter than previously thought. These short wavelength waves are more likely than their longer wavelength counterparts to breakdown close to the cloud top. It has been shown that this breaking occurs when above cloud wind shear induces a critical level aloft; such a critical level can occur if the change in wind speed is a mere 10 m/s. In this study, we conduct numerous high resolution simulations of convection with different wind and stability profiles. These simulations will be used to examine the occurrence and extent of above cloud gravity wave breaking and its sensitivity to changes in background flow conditions.
Joint Poster Session 5, Gravity waves--Poster-- (JOINT WITH MIDDLE ATMOSPHERE, FLUID DYNAMICS AND CLIMATE VARIATION
Tuesday, 14 June 2005, 4:30 PM-6:00 PM, Riverside
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