Parameterization of gravity wave momentum deposition based on nonlinear wave interactions: basic formulation and sensitivity tests

We present a practical method for parameterization of gravity wave drag bas ed on the Medvedev and Klaassen (1995. Journal of Geophysical Research 100, 25,841-25,853) theory of gravity wave spectral evolution and saturation. T he only tuning necessary for the scheme involves assumptions about the natu re of the source spectrum of subgrid-scale gravity waves, i.e. the wavenumb ers, launch heights and amplitudes of the spectral components. In this pape r we employ a column model with representative distributions of mean wind a nd temperature to examine the sensitivity of the parameterized wave drag to the source spectra. For the range of anticipated variability of source spe ctra in the troposphere the scheme produces plausible results consistent wi th observations and with theoretical estimates. Computationally, the scheme is as efficient as a multiple-wave Lindzen scheme, and suitable for use in general circulation models (GCMs) of the atmosphere. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.