Athulya Radhakrishnan

Abstract

The mechanism behind extreme rainfall events (rainfall ≥ 150mm) over central India during the months of June – September is studied using high resolution daily gridded rainfall data. The present study shows that extreme rainfall events have been significantly increasing over the central India (at about 1 event per 2 years) from 1982-2012 with year to year variability. In contradiction with previous studies, current study shows that monsoon depressions forming over the Bay of Bengal and the Arabian Sea are not playing a major role in the extreme rainfall events over central India. Further, it has been found out that an amplification of the synoptic scale moisture convergence is leading to the increase in extreme rainfall events over the study region. The analysis of vertically integrated moisture flux and zonal wind circulation on extreme rainfall days give compelling evidence of an anomalous moisture transport from the western Indian Ocean and its convergence over central India. A warming ocean and atmosphere can be accounted for the increase in the moisture availability in the atmosphere which along with the anomalous moisture transport, results in an increase in extreme precipitation events and floods over central India.