Thermodynamic Adjustment Parameters in the Betts–Miller Scheme of Convection

Abstract

The sensitivity of the prediction of a monsoon depression to the adjustment parameters in a Betts?Miller scheme of deep convection is examined and an optimum parameter set is identified for the monsoon depression. For this purpose, a number of experiments have been carried out with a limited area model by assigning different values to the adjustment parameters, namely, the saturation pressure departure, the stability weight, and the adjustment time period. When one parameter is varied, the other two are kept constant. Results indicate that the depression track is sensitive to all three adjustment parameters. The upper-tropospheric temperature is sensitive to the stability weight and the rainfall rates are sensitive to the saturation pressure departure values. The rainfall shows minor sensitivity to the stability weight and the adjustment time period. A set of adjustment parameters that produced the best forecasts is taken as the optimum parameter set for the monsoon depression.