The Effects of Topography on the Atmospheric Energetics in. a Low-Resolution General Circulation Model

Abstract

Abstract An analysis is made of the effect of orography on the atmospheric energetics in a low-resolution general circulation model to determine the temporal and scale dependency of these effects. The numerical model is a global, spectral, primitive equation model of the atmosphere with five equally spaced sigma levels in the vertical and triangular truncation at wavenumber 10 in the horizontal. A one-year seasonal simulation of the general circulation without mountains is compared to the results from a five-year seasonal simulation of the general circulation with mountains. The statistical significance of the topographic effects is evaluated by comparing them to magnitudes of model interannual variability determined from the five-year control simulation. A small, but important, portion of the changes due to topography are significant. At northern extratropical latitudes, the increases of eddy activities and baroclinic instability in summer resulting from incorporation of the effect of the mountains give ...