The Akio Arakawa Symposium


Representing the effects of atmospheric waves in large-scale atmospheric models

Young-Joon Kim, NRL, Monterey, CA

Parameterizing the effects of orography in terms of drag imposed on the atmosphere due to atmospheric waves is an important part of global atmospheric modeling, both for short-term weather prediction and long-term climate simulation. The spatial scale of orography in consideration ranges from grid-scale, to subgrid-scale, and further to micro or turbulence scale. The vertical range of the effects covers from the surface to the top of the atmosphere. The problem of orographic drag parameterization, therefore, spans widely in both space and time, and has evolved into a complicated science that requires comprehensive knowledge. The sources of the waves are not only orography, but also convective systems and atmospheric jets, to name the most popular. The spectrum of waves can be stationary over mountains in the lower atmosphere while it is largely nonstationary in the middle atmosphere as well as in the lower atmosphere over convective systems. The formulations to determine the source, propagation, and breaking of the waves started from a linear single-wave theory, but have evolved into full wave-spectrum nonlinear theories. Representing this complex phenomenon in large-scale models became one of the most challenging aspects in atmospheric modeling. The suggestion of Professor Arakawa to study the effects of “envelope orography” for the UCLA General Circulation Model was the starting point of my research on gravity waves. My research quickly evolved into the simulation of subgrid-scale orographic waves and their parameterization for large-scale models. It continued on to include sources other than orography, to extend from the lower atmosphere to the middle atmosphere, and to application to weather forecast models. At the conference, I will present my research on this subject in line with the current status of gravity-wave drag parameterization in the research and operational communities.

Poster Session 1, Poster Session
Tuesday, 16 January 2007, 9:45 AM-11:00 AM, Exhibit Hall C

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