A study of sea surface temperature and pressure patterns over the Indian Ocean regions in some years of contrasting SW monsoon rainfall in India

Abstract

A study is made of the sea surface temperature and pressure patterns for different months over Indian Ocean (north of 15 deg. S and between 40 deg. E and 100 deg. E) with the help of marine annual summary data published for the years 1961, 1964 and 1965, 1966.

The zone of warmest sea surface waters during the months of April and May was observed to be located northward in the years 1961 and, 1964, the years of good monsoon over India as compared to 1965 and 1966, the years of bad monsoon over India. The values of SST were also higher for most of the oceanic areas in the years 1961 and 1964 as compared to 1965 and 1966.

Well defined pressure patterns with isobars 1008 and 1009 mb encircling and pressure gradient directed towards Indian Peninsula were observed during the months of April in 1961 and 1964 but in 1965 these features in the pressure pattern were absent.

A general fall of SST values ranging from 1 deg. to 3 deg. C was observed during the monsoon months in most of the oceanic areas. Besides, a study has been made of the seasonal variation of SST and pressure and some probable explanation has been offered for the appearance of coldest waters along north Somali coast to east Arabia coast during monsoon season (June to September).