South-West Monsoon Rainfall of Kerala and Its Variability

Abstract

This study focuses on the south –west monsoon rainfall over Kerala and its variability both on the spatial and temporal scales. The main objectives of the study are, interanual, long-term and decadal variabilities in MRF(monsoon rain fall),relationship between antecedent global circulation parameters, diurnal variability using data of a large number of stations in Kerala and the spatial distribution of rainfall under two large scale synoptic. Kerala gets nearly 190cm of rainfall during the south-west monsoon season 1st June to 30th September. This is more than twice the monsoon rainfall of India. A good part of kerala’s rainfall is caused by the orography of the Western Ghats Mountain ranges. The state receives 286cm of annual rainfall of which 68%is during the south-west monsoon season. The summer monsoon rainfall of Kerala shows a decreasing trend of 12.0%in 96 years. The study shows that the Intra Seasonal Oscillations(ISO) of the monsoon season has large interanual variability,some years having long period and other years having short period ISO. It is seen that Western Ghats has a strong control on the east west profile on the monsoon rainfall.