Role of the ITCZ over the north Indian ocean and Pre-Mei-Yu front in modulating July rainfall over India

Abstract

Southwest monsoon rainfall over India during July 2002 was the lowest since instrumental records of rainfall data have been available. The present study is an attempt to examine some of the probable causes for this unprecedented low rainfall during July. It is found that the strength of the intertropical convergence zone (ITCZ) over the north Indian Ocean and the pre-mei-yu front over the northwest Pacific Ocean during the month of May has significant positive correlation with the July rainfall over India, and it can be used as a precursor for predicting July rainfall over India. The activity of the ITCZ over the north Indian Ocean and pre-mei-yu front in May is an indicator of the strength of first monsoon intraseasonal oscillation (ISO). It was also found that the ITCZ over the north Indian Ocean and pre-mei-yu front were not active during May 2002, probably because of the weak ISO activity during the first half of the monsoon season.