Applying the Betts–Miller–Janjic Scheme of Convection in Prediction of the Indian Monsoon

Abstract

The performance of the Betts?Miller?Janjic scheme of convection has been investigated for prediction of the Indian monsoons. For this purpose a limited area numerical weather prediction model with two schemes of convection, one with the Betts?Miller scheme and other with the Betts?Miller?Janjic scheme, is run for five cases of monsoon depression that made landfall over the Indian coast. The results from the two schemes are compared. Detailed analyses of mean sea level pressure, wind, and rainfall have shown that the Betts?Miller?Janjic scheme has considerably improved the rainfall prediction over the Indian landmass and improvement is also seen in the mean sea level pressure fields and cyclonic circulation associated with the depression at the 850-hPa level. The forecast results are further verified by computing the root-mean-square errors, and the difference in the skill scores between the two model runs are tested for their statistical significance. It is found that the Betts?Miller?Janjic scheme has a statistically significant effect on the model skill beyond 24 h, with maximum impact on mean sea level pressure and geopotential height.