Journal of the Marine Biological Association of India

Onset and advance of southwest monsoon along west coast of India

Volume 14 Issue 2

A. S. Ramanathan

Abstract

The problem of the onset of south-west monsoon over Kerala and Its advance along the West-coast has been investigated for the period 1956-1969 making use of the extended charts for the surface and 500 mb. It is shown that the following extra>tropical synoptic features have a strong influence on the onset of monsoon over Kerala and its advance  long the west coast.

1. Variations of trough ridge pattern at 500 mb as observed between 40⁰ and 50⁰

round 60⁰E (Aral Sea region) during May and June.

2, The nature of monsoon activity over coastal Burma at the time of onset of monsoon over Kerala and during the subsequent period in May and June.

In the light of the above synoptic features, the late and early arrival of monsoon over Kerala, its quick and slow advance along the west coast and its temporary weakening and revival during the months of May and June are examined in detail. The formation of low pressure arras over Arabian Sea and the subsequent intensification of some of them during the months of May and June is also examined and its association with the synoptic features

listed above is discussed. A passing reference has also been made to the heavy rainfall over Kerala and coastal Mysore during July 1968 and relevant remarks made on the same. 

Date : 30-12-1972