Seasonal transition of precipitation characteristics associated with land surface conditions in and around Bangladesh

Abstract

This study examined the seasonal transition of precipitation characteristics and its association with land surface conditions in and around Bangladesh, where land surface conditions are predominantly wet. Hourly rain rate data from the Global Satellite Mapping of Precipitation Microwave‐Infrared Combined Product and 10 day soil moisture data from the Advanced Microwave Scanning Radiometer Earth Observing System were used over the 7 years from 2003 to 2009. Area mean values of soil moisture, and precipitation amount, frequency, and intensity were calculated for each 10 day period. Results showed that higher precipitation amount and frequency were observed over the wet soil conditions, which indicates that soil moisture was influenced by previous precipitation events. However, the soil moisture could also control the precipitation characteristics. The seasonal and interannual variations in all regions suggested that precipitation amount and frequency increased in moist soil conditions, which is associated with an increase of water vapor supplied from the moist land surface. Over a flat plain (87°E–91°E, 23°N–25°N), a higher afternoon precipitation intensity was observed over drier land surfaces. This relationship was observed on seasonal and interannual variations. This suggests that the land surface conditions in this region can affect the afternoon precipitation intensity to some extent, although changes of atmospheric conditions can be a major factor particularly for the seasonal changes. However, this relationship was not observed in mountainous regions. This can be explained by other factors, such as thermally induced local circulations by the surrounding topography, being stronger than the impact of land surface conditions.

Weakening of rainfall intensity on wet soils over the wet Asian monsoon region using a high-resolution regional climate model

“…Although many numerical studies have shown the simulated evidence, it is generally difficult to obtain observational evidence. For example, Ono and Takahashi (2016) and Takahashi (2016) showed a similar tendency of the effect of land-surface conditions on rainfall intensity over the wet Asian monsoon region from observed datasets. However, more studies are required to fully understand the mechanisms of these responses.…”

Lightning activity associated with precipitation and CAPE over Bangladesh

“…We also found positive correlation during pre‐monsoon ( r = 0.663) than monsoon ( r = 0.455). Relatively low correlation in this study may be attributed to a variety of factors such as mesoscale convective system of the region (Choudhury et al ., ), seasonal transition of precipitation characteristics (Ono and Takahashi, ), cloud height, intensity of rainfall, ice content per lightning flash and properties of precipitation systems (Islam and Uyeda, ; Lal and Pawar, ; Rafiuddin et al ., ). Rafiuddin et al .…”

The role of local topography and sea surface temperature on summer monsoon precipitation over Bangladesh and northeast India

“…Phase 1 and 2 of the MJO circulation creates a strong moisture convergence near the Meghalaya Plateau, leading to intensified precipitation over northeast India and the northern Bangladesh region during the summer monsoon. Several studies have also reported that changes in soil moisture contribute to the pre‐monsoon and monsoon precipitation variation over Bangladesh (Ono and Takahashi, 2016; Sugimoto and Takahashi, 2017).…”