Seasonal monsoon forecast for the years 1987 and 1988

The results of several seasonal integrations with an atmospheric global circulation model with prescribed “perfect” sea surface temperatures are presented. These experiments illustrate the results of seasonal simulations for the years 1987 and 1988. These were a dry and a wet monsson year, respectively, when compared to the average. The integrations cover the period from June 1 through August 31 for both years and were carried out at two horizontal resolutions, T42 and T106, of a global model containing two different parameterizations of surface hydrology. The seasonal differences of the motion fields, divergent circulations and rainfall distributions for these respective experiments are compared with the corresponding observed fields. The sensitivity of seasonal simulations to the initial state is explored with integrations starting on two successive dates. In these experiments we diagnose differences of the simulated time mean states from residue free budgets of the complete vorticity equation.