Regional and seasonal differences of radar reflectivity slopes in lower troposphere in convective and stratiform precipitation using TRMM PR data

Abstract

Abstract Slopes of radar reflectivity below freezing height (FZH) is a critical parameter to estimate the correct rainfall near the surface. TRMM PR based radar reflectivity slopes is presented here, during Indian and Austral summer monsoon by calculating them in lower troposphere (< 4 km). Slopes are either positive or negative, which means they are either decreasing or increasing towards the surface. In majority of cases, slopes decrease towards the surface over land, but increases towards the surface over ocean. A close similarity has been observed in the tropical oceanic areas in convective precipitation and Arabian Ocean consists of the highest fraction (89.10~%) of negative slopes, whereas Bay of Bengal has the highest fraction of positive slopes (21~%) in convective precipitation. Western Himalaya Foothills has the highest fraction of positive slope in convective precipitation and shows that ~ 76% and 83% of convective and stratiform profiles decrease towards the surface. During Austral summer monsoon Maritime Continent consists of the highest fraction of negative slopes (~ 92%%) in convective precipitation followed by Equatorial Indian Ocean. Land vs ocean and regional differences in radar reflectivity slopes are higher in convective precipitation compared to stratiform precipitation. Vertical profiles with extreme positive (> 1) slopes have higher ETH in convective precipitation over tropical ocean during both the seasons, whereas over the land higher ETHs are contributing to negative slopes.