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

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 are presented here, during Indian and Austral summer monsoon by calculating them in the lower troposphere (< 4 km). Slopes are either positive or negative, which means that the radar reflectivity either decreases (positive slopes) or increases (negative slopes) towards the surface. In the majority of cases, slopes decrease towards the surface over land, but over oceans increase towards the surface. In general, the slopes in convective tropical precipitation are negative where the Arabian Ocean has the highest fraction (similar to 89%) of negative slopes. However, Bay of Bengal has the highest fraction of positive slopes (similar to 21%). Western Himalaya Foothills has the highest fraction of positive slopes in convective precipitation and shows that similar to 76% and similar to 83% of convective and stratiform profiles decrease towards the surface. During the Austral summer monsoon, the Maritime Continent has the highest fraction of negative slopes (similar to 92%) in convective precipitation followed by the 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 dBZ/km) slopes have higher echo top height (ETH) in convective precipitation over the tropical ocean during both the seasons, whereas over land, higher ETHs are associated with negative slopes.