Bangladesh is greatly susceptible to the impacts of climate change. Climate change has enhanced the frequency and intensity of extreme events in Bangladesh, thus resulting in loss of biodiversity and agricultural crop production. However, trend studies in the frequency of climatic variables like rainfall at the micro-scale are less explored in the previous literature. Therefore, this study aims to explore the spatiotemporal trends in the frequency of daily rainfall using different statistical models based on 23 station data from 1975 to 2017 in Bangladesh. The statistical results show that the frequency of rainfall ranges of < 5 mm, > 10 to ≤ 15 mm, > 15 to ≤20 mm, and > 25 to ≤ 30 mm exhibited an increasing trend while rainfall ranges of > 5 to ≤ 10 mm, > 20 to ≤ 25 mm, > 30 to ≤ 35 mm, and > 35 mm displayed a decreasing trend (p > 0.10). The jump test results indicate that only one jump occurred in the average rainfall ranges of > 15 to ≤ 20 mm (p < 0.10). The changes in temporal trends of different rainfall frequency ranges show an irregular pattern during the study period. The spatial map of trends among various rainfall ranges over sub-climatic regions is heterogeneous nature which varies from region wise and station wise. The probability density function (PDFs) of rainfall frequency ranges will move upward in the future and broaden with an increase in the forthcoming period. To adapt to climate change, the findings highlight the need for the advancement of water resource management and reallocation of agricultural adaptation plans in Bangladesh.

孟加拉国非常容易受到气候变化的影响。气候变化增加了孟加拉国极端事件的发生频率和强度，从而导致生物多样性丧失和农作物生产。然而，在以前的文献中很少研究诸如降雨等气候变量频率的趋势研究。因此，本研究旨在基于1975年至2017年孟加拉国的23个台站数据，使用不同的统计模型探索日降雨频率的时空趋势。统计结果表明，降雨范围<5 mm，> 10到≤15 mm，> 15≤≤20 mm，> 25到≤30 mm的频率呈现增加趋势，而降雨范围> 5到≤10 mm ，> 20至≤25 mm，> 30至≤35 mm和>p > 0.10）。跳跃试验结果表明，在平均降雨量> 15至≤20 mm时，仅发生了一次跳跃（p <0.10）。在研究期间，不同降雨频率范围的时间趋势变化显示出不规则的模式。亚气候区域内各种降雨范围之间趋势的空间图是异质性的，它在区域和站点之间是不同的。降雨频率范围的概率密度函数（PDFs）将来将向上移动，并随着即将到来的周期的增加而扩大。为了适应气候变化，调查结果强调了孟加拉国需要加强水资源管理和重新分配农业适应计划。