A Study of South Asian Monsoon Convection and Tropical Upper Easterly Jet During Northern Summer 1991.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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This work studies the 1991 northern summer monsoon over India and surrounding areas using Japanese GMS and Indian INSAT geostationary satellite data, the ECMWF objective re-analysis, and the NMC sea surface temperature analysis. Monthly and weekly mean fields are first used to examine the development of the monsoon over the entire domain and to identify the timing of the onset over India. Latent heat fluxes are shown to be important in the monsoon development process. The relationship between the synoptic variations of a convective index derived from satellite data and the upper tropospheric easterly jet show two possible effects of cumulus convection on the easterly jet. The first is a forcing of the jet maximum near southern India when convection flares up to the north in the monsoon trough. This is believed to be the result of the Coriolis acceleration of the southward outflow of the local Hadley cell. The second is a damping of the upper jet by cumulus momentum transport that occurs at the same location as the jet maximum. This second effect is most clearly shown in regions of strong vertical shear.