The Role of Parameterized Drag in a Troposphere-Stratosphere-Mesosphere General Circulation Model

This paper discusses simulations of the global circulation up to 0.01 mb obtained using a general circulation model with an imposed zonal wind relaxation that forces the zonal-mean state close to observations. This enables estimates to be made of the zonal drag required to bring general circulation model simulations of the middle atmospheric circulation into line with observations. The diagnosed drag is then compared with results from the Lindzen (1981) parameterization of wave drag from unresolved gravity waves. With reasonable values of the wave input parameters, the parameterization can capture many of the features of the diagnosed drag distribution, but only if some modification of the Lindzen procedure is adopted to allow the region of parameterized wave breaking to extend to lower heights.