Morphology of the vertical structure of precipitation over India and adjoining oceans based on long-term measurements of TRMM PR

Abstract

The spatial and seasonal variability of the vertical structure of precipitation has been studied using 15 years of Tropical Rainfall Measuring Mission's Precipitation Radar (TRMM PR) version 7 data over India and adjoining oceans. Special emphasis has been put on six different climatic rain regimes and on different types of precipitation including the virga rain. The distribution of reflectivity factor (Z) above the freezing level height is broader in northwest India (NWI) and narrower over the Arabian Sea and west coast of India (ASWC) than in other selected regions, due to dominance of deep and shallow convective rain, respectively, in those regions. The height variation of contours in normalized distributions for Z indicates that evaporation of raindrops (low-level hydrometeor growth) could be significant in NWI (ASWC and Bay of Bengal). All the above features show clear seasonal variation and are observed predominantly during the southwest monsoon. The occurrence of virga rain clearly shows land-ocean contrast (less over the oceans) and seasonal variation (preponderant during premonsoon). Among different rain categories, the stratiform (convective) rain had highest (lowest) fraction of virga rain of >15–30% (<10%) over land regions. 1. The storm height (SH) vertical distributions show a peak in the vicinity of bright band (BB) in all regions, except for those regions and seasons, where convective precipitation is dominant. The well-defined BB feature and SH exhibit significant seasonal and regional variations, which are linked to variations in the occurrence of stratiform rain and height of BB. The spatial and seasonal variations of mean SH and the occurrence of deep and overshooting convective rain show good correspondence with the spatial variation of convective available potential energy.