NUMERICAL EXPERIMENT ON THE SEASONAL TRANSITION OF GENERAL CIRCULATION OVER ASIA - PART Ⅰ

The onset of the 1979 summer monsoon is investigated using the ECMWF grid-point model. The role of the Tibetan Plateau in this process is investigated by means of parallel model integrations with different orographies. Similarly, the relative roles of land-sea thermal contrast, latent heat release and Southern Hemisphere influence are studied. The influence of the African Highland on the onset of the Somali jet is also explored. A generally satisfactory performance of the model in representing the onset of the monsoon is documented and various contributions to this from different model components are discussed. In Pan I of this paper the impact from the Southern Hemisphere is presented.