The study explores the spatial variability and related characteristics of south Asian summer monsoon rainfall and extreme rainfall events based on APHRODITE rainfall products. An attempt was also made to investigate their association with global climate indices. Most of the South Asian regions are vulnerable to extreme rainfall events and many of these lead to major hydrological disasters. Such events are adversely affecting flora and fauna, causing large-scale damage to the livelihood and economy. We have analysed the characteristics of extreme rainfall events during the summer monsoon season for 65 years (1951–2015). The statistical method based on the percentile of daily rainfall amount (>99th percentile) was used to identify the extreme rainfall zones. We have also attempted to explore the spatio-temporal features and heterogeneity of these extreme events at a finer spatial resolution. We examined the linear trend of these extreme rain events on the spatial domain and found that extreme rainfall decreases over northcentral Indian and southwestern coastal belts. An increase in the frequency and amount of rainfall from extreme rain events were observed in the western coastal belts between 16° to 20° N and central Indian regions along with the coastal areas of Bangladesh and Myanmar. The linear trends of extremes exhibit remarkable differences from the trends of seasonal rainfall. The results from the probability density function (PDF) analysis are also supporting the trend analysis of mean and extremes in all the five regions. It was also observed a distinct shift in the PDF curve during the pre and post 1980 periods. Moreover, we have analysed the relationship of various climate indices (Niño3.4, Modoki, DMI, PDO, AMO, and AZM) with the mean and extreme rainfalls in addition to the spatial trends. Most of the indices show a significant inverse relationship with mean and extreme rainfalls. The areas of significant correlation are less in the case of extreme rainfall while comparing with that of the mean rainfall.

该研究基于APHRODITE降雨产品探索了南亚夏季风降雨和极端降雨事件的空间变异性及相关特征。还尝试调查它们与全球气候指数的关联。大多数南亚地区容易受到极端降雨事件的影响，其中许多会导致重大水文灾害。此类事件对动植物群产生不利影响，对生计和经济造成大规模破坏。我们分析了 65 年（1951-2015 年）夏季风季极端降雨事件的特征。采用基于日降雨量百分位（>99%）的统计方法识别极端降雨区。我们还尝试以更精细的空间分辨率探索这些极端事件的时空特征和异质性。我们在空间域上检查了这些极端降雨事件的线性趋势，发现印度中北部和西南沿海带的极端降雨减少。在北纬 16 度至 20 度之间的西部沿海地带、印度中部地区以及孟加拉国和缅甸的沿海地区，极端降雨事件造成的降雨频率和降雨量有所增加。极端降水的线性趋势与季节性降雨的趋势存在显着差异。概率密度函数的结果 ( 我们在空间域上检查了这些极端降雨事件的线性趋势，发现印度中北部和西南沿海带的极端降雨减少。在北纬 16 度至 20 度之间的西部沿海地带、印度中部地区以及孟加拉国和缅甸的沿海地区，极端降雨事件造成的降雨频率和降雨量有所增加。极端降水的线性趋势与季节性降雨的趋势存在显着差异。概率密度函数的结果 ( 我们在空间域上检查了这些极端降雨事件的线性趋势，发现印度中北部和西南沿海带的极端降雨减少。在北纬 16 度至 20 度之间的西部沿海地带和印度中部地区以及孟加拉国和缅甸的沿海地区，极端降雨事件引起的降雨频率和降雨量有所增加。极端降水的线性趋势与季节性降雨的趋势存在显着差异。概率密度函数的结果 ( 极端降水的线性趋势与季节性降雨的趋势存在显着差异。概率密度函数的结果 ( 极端降水的线性趋势与季节性降雨的趋势存在显着差异。概率密度函数的结果 (PDF ) 分析还支持所有五个区域的均值和极值的趋势分析。还观察到 1980 年前后和 1980 年后 PDF 曲线的明显变化。此外，除了空间趋势外，我们还分析了各种气候指数（Niño3.4、Modoki、DMI、PDO、AMO 和 AZM）与平均和极端降雨量的关系。大多数指数与平均和极端降雨量呈显着负相关。与平均降雨量相比，极端降雨情况下相关性显着的区域较少。