Bangladesh is under the strong influence of the South Asian monsoon. Extensive damages caused by frequent severe flood events in this country call for a study of nationwide precipitation climatology. Here, we examine spatiotemporal variations of precipitation in Bangladesh using rain gauge data at 35 stations for the period 2003–2016. The annual precipitation amount in Bangladesh is 2263 mm, and it shows large spatial variations. The annual precipitation amount is large in the southeastern coastal region of the country and the region close to the Meghalaya Plateau, and it is small in the west central region. 17% and 73% of the annual precipitation amount are observed in the pre-monsoon season (March to May) and monsoon season (June to September), respectively. The pattern of the diurnal variation of precipitation differs depending on regions of Bangladesh. In the northern region of the country, the precipitation maximum occurs in the late night to early morning in both the pre-monsoon and monsoon seasons. The late night to early morning maximum of precipitation is associated with the large horizontal convergence of low-level water vapor flux. The Himalaya Mountains and the Meghalaya Plateau together with more nighttime moisture transport due to the strengthened nighttime low-level wind seem to play roles in enhancing nighttime precipitation. In the southwestern region of the country, the precipitation maximum is observed in the early evening in the pre-monsoon season, which is associated with the large convective instability in the afternoon, and it is observed in the early afternoon in the monsoon season. In the southeastern region of the country, the diurnal variability of precipitation is smallest in the pre-monsoon season compared with other regions of the country in the pre-monsoon and monsoon seasons and the precipitation maximum occurs in the late night to early morning in the monsoon season.

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全国雨量计数据显示孟加拉国降水的时空变化

孟加拉国受到南亚季风的强烈影响。由于该国频繁发生的严重洪灾事件而造成的广泛破坏，要求对全国降水气候学进行研究。在这里，我们使用2003-2016年期间35个站点的雨量计数据检查了孟加拉国的降水时空变化。孟加拉国的年降水量为2263毫米，其空间变化很大。该国东南沿海地区和靠近梅加拉亚高原的地区的年降水量较大，而在中西部地区的年降水量较小。在季风前季节（3月至5月）和季风季节（6月至9月）分别观测到年降水量的17％和73％。降水日变化的模式因孟加拉国的地区而异。在该国北部地区，最大的降雨发生在季风前和季风季节的深夜至清晨。从深夜到清晨，最大的降水与低水平水汽通量的大水平收敛有关。喜马拉雅山脉和梅加拉亚邦高原以及夜间低水平风的增强导致夜间水分输送更多，似乎在增加夜间降水方面发挥了作用。在该国西南地区，季风前季节的傍晚观测到最大的降水量，这与下午的大对流不稳定有关，在季风季节的午后观测到。在该国东南地区，与季风前和季风季节的该国其他地区相比，季风前季节的降水的日变化最小，并且最大降水发生在深夜和清晨。季风季节。