Abstract
The main features of the monsoon are first described emphasising particularly its essentially interhemispheric character and showing how the latent heat release associated with the rainfall over India and its neighbours and radiative cooling over the Indian Ocean determine the monsoon flow at lower and upper levels.
An area is then selected between 22.5°N and 32.5°S, and 37.5°E and 117.5°E for estimating surface transfers of latent and sensible heat and net tropospheric heating for the six half-monthly periods of June-August 1990 using ECMWF operational analyses. The results show that less than a quarter of the surface energy input is exported from the region; the rest is offset by radiative cooling, mainly over the S. Indian Ocean.
It is inferred that much of the observed variability associated with the location and intensity of monsoon rainfall, at least on time scales up to about a month, are determined primarily by feed-back mechanisms within this region. It is proposed that such studies, carried out routinely and linked to limited area numerical experiments, could contribute substantially to our understanding of these processes. At the same time analyses of the much smaller lateral boundary fluxes could enable the nature of the interaction of the monsoon circulation with larger scale phenomena such as ENSO to be separately identified and quantified.
