Sea and air temperatures distribution over the Arabian Sea during southwest monsoon, 1973

Abstract

Based on MONEX 1973 data, the sea surface and air temperatures in the troposphere over the Arabian Sea during spells of active and weak monsoon over India have been analysed.

            The studies show that a cold area lies off Kerala coast and a cold tongue extends from off Somalia coast to central Arabian Sea in the lower troposphere during both the spells. Isotherms are parallel to the Arabian coastline with temperatures falling steeply seawards. Temperature gradient reverses at 500 mb over coastal Arabia during he eastern cloud both the spel19andover coastal Maharashtra during weak monsoon, but aloft the north to south temperature gradient with isotherms running east to west is maintained. There is no reversal of temperature gradient at any level over north Arabian Sea and Pakistan coast. The sea is warmer than the air during active monsoon off the west coast of India and colder than the air during weak monsoon. This feature is in some way associated with the development of a trough of low pressure off the west coast during active monsoon and 81 rid e during weak monsoon.

           No significant difference in the temperature andm9isture contents is observed between the two spells in the very low levele. The lower and middle troposphere, however, near the equator is generally cool and moist during weak monsoon while over the central and northern parts of the Arabian Sea, it is warmer and much drier than during active monsoon.

         The veering and strengthening of the westerlies up to about 1.5 km a.s.1 resulting in the low level westerly jet appears to be mainly a frictional effect in- the surface layers.