Numerical simulation of the Indian monsoon

Abstract

A review of current work in India on modelling experiments is presented. The experiments are designed to simulate different features of the Indian summer monsoon. The first part of the paper summarises the basic structure of a model, and the problems of computational design. Different grid structures and transformation of the vertical coordinate to include mountains are discussed. Experiments are suggested for minimising truncation errors by using different reference atmospheres, and by normal mode initialisation. A brief account is provided of the use of finite elements for numerical models. The latter half of the paper deals with different physical processes in the atmosphere. They are (i) the radiation balance of the atmosphere, (ii) clouds and precipitation, (iii) frictional effects, and (iv) sea surface temperature. The results of models developed in India are compared with those obtained by general circulation models. It is shown that present models succeed in simulating certain features of the monsoon fairly well, but further work is needed to simulate other aspects, such as, rainfall.