Investigation of Nonlinear Gravity Waves in the Earth's Atmosphere

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A high resolution, time dependent, nonlinear, two- dimensional gravity wave model will be used in a series of investigations to understand the dynamics of gravity wave forcing, propagation, breakdown, and their role in modifying larger scale motions in the atmospehre. These studies will use simulations of idealized flow situations to clarify basic dynamical processes in parallel with more realistic simulations to understand the magnitude and distribution of gravity wave effects in the atmosphere. Our numerical studies will be guided by estimates of mountain wave generation and propagation determined from NMC global wind and temperature analyses and global topographic data. These investigations will also involve use of observational data from the Flatland radar system as well as NASA's aircraft experiments to verify model results. The ultimate objectives of this project are to estimate the amount of gravity wave flux escaping from the troposphere as a function of mean flow conditions and topography and to develop parametrization schemes for gravity wave stress and transport to be used in general circulation models. Results from this investigation may also help to clarify the effect of small-scale (less than 100 km) variability on the transport and microphysics of aerosols and PSC's in the stratosphere. A second objective of the proposed research will be to investigate the dynamics of large amplitude atmospheric solitary waves with a series of numerical experiments. The PI's experiments will be guided by both theoretical analyses of solitary wave properties and by direct observations of atmospheric solitary waves from the Flatland Radar. The PI's studies will be especially concerned with examining the sensitivity of solitary wave structure of the background atmospheric flow.