Air-mass dynamics or subsidence processes in the Arabian Sea monsoon

Soundings over the Arabian Sea during the International Indian Ocean Expedition period and climatological data over the west coast of India have been discussed to determine the cause of the low-level inversion and the influence of the Western Ghats on the inversion and precipitation. There does not appear relation between maximum divergence and lowest height of base of inversion as presumed by Flohnet al. The pattern of precipitation frequency on the west coast as seen from Fig. 2 of Ramage does not show the same trend either as the number of rainy days or rainfall at the coastal observatories. The depth of the moist layer and the height of base of inversion increase as the Western Ghats are approached, such changes not occurring off west Kathiawar-Kutch-Sind where there are no orographic barriers on the coast. The air-mass considerations to explain the low-level inversion over the Arabian Sea, would appear substantially valid even now.