Monsoon onset over Kerala and pre monsoon rainfall peak

Abstract

In the present study the pentad Global Precipitation Climatology Project (GPCP) estimate have been used, which is a blended product of microwave, infrared and in-situ gauge data for the region bounded by 8 ° - 13 ° N; 70 ° - 95 ° E, from 1^st March to 31^st May for the years 1979 to 2001. The monsoon onset dates over Kerala, as declared by India Meteorological Department has been used in the present study. For each year, the midday of the pentad with the rainfall peak was looked for in the period from 1^st April to 10^th May and identified as the Pre Monsoon Rainfall Peak (PMRP). The analysis showed that PMRP exists about seven pentads prior to the onset of the monsoon over Kerala coast. The correlation between PMRP date and the monsoon onset date over Kerala was found to be 0.72, which was statistically significant. Thus, as is felt that the pre monsoon rainfall estimate from the satellite data can be used for predicting the monsoon onset over Kerala coast. The results and the methodology used are briefly presented.