Toward an ultra-simple spectral gravity wave parameterization for general circulation models

Abstract

This paper reports first steps toward a computationally inexpensive spectral gravity wave parameterization scheme whose predictions approximate those of a full three-dimensional (in spectral space) spectral model of atmospheric gravity waves. A reduction to two dimensions, as proposed by Hines, requiring the neglect of Coriolis and non-hydrostatic effects, is explored on the basis of comparisons with a full three-dimensional power-spectral model that includes Coriolis and non-hydrostatic effects. The reduction tries to be more realistic in terms of spectral shapes, though simpler in terms of wave-breaking criteria. It works remarkably well in the absence of, but less well in the presence of, background shear. The reasons for the discrepancies are under investigation, as are the implications for two-dimensional schemes, including Hines' as well as ours.