Intraseasonal variation of the Indian summer monsoon. II. Theoretical aspects

Abstract

A class of simple zonally symmetric models of increasing complexity have yielded increasingly realistic simulations of the intraseasonal variation of the tropical convergence zone (TCZ) over the Indian region in the summer. A new model in this class, incorporates the space-time variation of surface pressure. As in the earlier models, the prominent feature of intraseasonal variation in the Indian region viz. poleward propagations of the TCZ is simulated. The rate of propagations in this model is more realistic and the period between propagations is also more realistic, being about thirty-five days. A new feature simulated by the model is the active phase of the monsoon with the TCZ persisting over the continental trough for about 20 days.