Diurnal and spatial variation of Indian summer monsoon rainfall using tropical rainfall measuring mission rain rate

SummaryThis paper deals with the diurnal and spatial variation of summer monsoon (JJAS) rainfall, extremes and its frequency for a period of 12 years using the TRMM (Tropical Rainfall Measuring Mission) rain rate data set. Rainfall and frequency of rain events are more observed over the western coastal belts, northeastern regions, foothills of Himalayas and Bay of Bengal regions. Average seasonal rainfall is about 400 mm from 150 rainy hours. The rainfall amount and frequency of rain events show a peak at 1730 IST over Central India, 0230 IST over the foothills of Himalayas and 0830 IST over the north Bay of Bengal. Rainfall over the west coast is more evenly distributed throughout the day. Diurnal pattern of rain intensity is different than that of the rainfall, it is more over the Gujarat regions and peak is observed at 1730 IST and 0230 IST. The relative contribution of rainfall by each octet towards the seasonal total is different. Contribution of rainfall towards its seasonal is maximum at 1730 IST over the main land and is different over other regions. In addition to this, the diurnal pattern of high intensity (90th percentile and above) and low intensity (10th percentile and below) rainfall during the season were also analyzed to find out their spatial distribution. We found that the diurnal pattern is more prominent for the high intensity rainfall than that for the low rainfall intensity. Maximum rainfall hours show systematic southward propagation from early morning to late night.

► The average diurnal pattern of seasonal rainfall is explained in detail.
► Explained the diurnal pattern of number of events of seasonal rainfall.
► Explained the spatial and diurnal structure of high and low rainfall activities.
► Studies the spatial structure of trough and crest of the rainfall over Indian domain.