Precipitation characteristics around Bangladesh revealed by TRMM data

Bangladesh region is interesting regions in a core region of the Asian monsoon. The Bangladesh region is a very flat region facing to the Bay of Bengal. The precipitaion characteristics are studied using the long-term Tropical Rainfall Measuring Mission (TRMM) data. Over the Bangladesh, the stability of the atmosphere seems to affect the precipitation system in the vertical profiles. In the pre-monsoon season, rain rate increases with height in the lower part of the profile, while in the mature monsoon season, rain rate is nearly constant in the lower part of the profile. The structure of precipitation system is more persistent and homogenous in the mature monsoon season. The rain top is higher in pre-monsoon season than in mature monsoon season. The rain total is generally determined by rain frequency. The horizontal size of the precipitation systems is larger for pre-monsoon season than for mature monsoon season. In other words, the precipitation system is small but many in the mature monsoon season. This fact may be explained that the atmosphere is sufficently humid to be easily triggered by small liftings. These characteristics are reflected in the rain retrieval biases in precipitation radar and microwave radiometers in space.