In the present paper, the variabilities and long-term trends of summer monsoon rainfall for different intensity bins (dry, low, moderate, high, very high, and extreme) are studied for five homogeneous regions, namely Northeast India (NEI), Northcentral India (NCI), Northwest India (NWI), Westcentral India (WCI), and Peninsular India (PI) for 118 years (1901–2018). The study was carried out based on gridded rainfall data from the India Meteorological Department (IMD). The rainfall characteristics such as number of rainy days, percentage contribution, and periodicity of rainfall intensity classes are analysed and found to be different in different homogeneous regions. The long-term trend (1901–2018) of total rainfall showed a significant increasing trend (19.9 mm decade⁻¹) in NEI and significant decreasing trends in NCI (9.6 mm decade⁻¹) and PI (4.9 mm decade⁻¹). Analysis on rainfall intensity indicates a significant increasing trend for high, very high, and extreme classes in NEI, a significant increasing trend for dry, and a decreasing trend for moderate and very high classes over NCI and PI. From correlation analysis among the homogeneous regions, it is found that the rain events in different intensity classes show different relationships, which indicate the regional heterogeneity in rainfall characteristics. It is also important to note that an increase in rainfall contribution from very high and extreme classes was found over NEI, NWI, and WCI in the multidecadal period of 1991–2018, while NCI showed a decrease during this period; however, in NCI, a drastic increase for these intensity bins is distinct during the 1961–1990 multidecadal period. In addition to the trends and variabilities, we also explored spatial heterogeneity of different rainfall intensity categories, and found remarkable differences from one homogeneous region to another.

在本文中，研究了印度东北部（NEI）、中北部五个均质区域（干燥、低、中、高、极高和极端）不同强度区间（干燥、低、中、高、极高和极端）夏季季风降雨的变化和长期趋势。印度 (NCI)、印度西北部 (NWI)、印度中西部 (WCI) 和印度半岛 (PI) 118 年（1901-2018 年）。该研究是根据来自印度气象部门 (IMD) 的网格降雨数据进行的。分析了降雨天数、贡献百分比和降雨强度等级的周期性等降雨特征，发现在不同的均质区域中是不同的。总降雨量的长期趋势（1901-2018 年）呈显着增加趋势（19.9 mm 十年^-1) 在 NEI 和 NCI（9.6 毫米十年^-1）和 PI（4.9 毫米十年^-1）的显着下降趋势）。对降雨强度的分析表明，NEI 的高、特高和极端等级有显着增加趋势，干旱有显着增加趋势，而 NCI 和 PI 的中和特高等级则呈下降趋势。从均质区域间的相关性分析发现，不同强度等级的降雨事件呈现出不同的关系，表明降雨特征存在区域异质性。还需要注意的是，在 1991-2018 年的几十年间，NEI、NWI 和 WCI 的极高和极端等级的降雨贡献增加，而 NCI 在此期间呈下降趋势；然而，在 NCI 中，在 1961-1990 年的几十年期间，这些强度区间的急剧增加是明显的。除了趋势和变化，