From downslope windstorms to gravity-wave drag: Evolution of the simulation and parameterization of gravity waves

Ever since Lilly and Zipser (1972) and Lilly (1972) depicted downslope windstorms and pointed out the need for representing the effects of mountain waves in large-scale models of the atmosphere, respectively, remarkable advances have been made in the area of orographic gravity wave studies. Personally, I was fascinated by these pioneering works of Dr. Douglass Lilly, which basically steered my career as an atmospheric modeler.

Over the years, I have been involved in simulating gravity waves generated by orography to understand downslope windstorms and in representing their effects in large-scale models of the atmosphere. My research has been expanded to more general area of parameterizing the effects of gravity waves due to nonorographic sources, such as convective systems, and of coupling orographic drag parameterizations into convective and spectral drag parameterizations for use in global atmospheric prediction systems with an extended model top.

The parameterization of gravity-wave drag is no longer a stand-alone problem. It involves close interactions with other drag mechanisms in the models and thus any attempt to parameterize its effects must be made in harmony with other physical mechanisms near the surface and aloft alike. I will present some results suggesting these arguments as well as my efforts to simulate and parameterize gravity wave drag. This presentation is dedicated to the leading pioneer in this field, Dr. Lilly.