This investigation highlights changes and various facets of inter-connections between rainfall over India and its prominent drivers such as Southern Oscillation (SO) and Indian Ocean Dipole (IOD). As the monsoon rainfall over majority of sub-divisions from Northeast India (NEI) and Central Northeast India regions (53% area) exhibits declining trend, which are reflected in annual rainfall (AR) as well. On the contrary, during the post-1971 period, the post-monsoon rainfall is observed to be decreasing over all the regions, except Peninsular India (PI). Moreover, the contradictory trends in monsoon and post-monsoon rainfall are registered over the PI, Northwest India (NWI) and West Central India regions. The significant increase in IOD (warming over Arabian Sea) is observed with a swift rise after 1960. Under changing climate conditions, a decline in rainfall and an increase in IOD Index (IODI) may aggravate the water scarcity challenge in semi-arid regions. More than 70% of sub-divisions has positive and negative relationship of SO with monsoon and post-monsoon rainfall, respectively. This contradiction is particularly observed over PI Region, which led to weaker SO-AR relationship. As compared to SO-rainfall relationship, almost opposite picture is observed in the case of sub-divisional and regional rainfall (monsoon and post-monsoon)-IOD relationship. The SO-AR relationship displays epochs of weak (1941–1970 and 1995–2016) and strong (1871–1941 and 1970–1995) connections. Interestingly, the strengthening of the IOD-AR relationship is responsible for the weakening of SO-AR and vice-versa, especially during the post-1970 period. It is evident that the strengthening of SO-IOD relationship results in good rainfall over India, as it shows a significant positive relationship and explains about 6 to 38% variations in regional and All-India annual rainfall.

这项调查突出了印度降雨与其主要驱动因素（如南方涛动 (SO) 和印度洋偶极子 (IOD) 之间的相互联系的变化和各个方面）。由于印度东北部 (NEI) 和印度东北部中部地区 (53% 地区) 的大部分分区的季风降雨量呈下降趋势，这也反映在年降雨量 (AR) 中。相反，在 1971 年后期间，除印度半岛 (PI) 外，所有地区的季风后降雨量都在减少。此外，在 PI、印度西北部 (NWI) 和印度中西部地区记录了季风和季风后降雨的矛盾趋势。观察到 IOD（阿拉伯海变暖）显着增加，并在 1960 年后迅速上升。在不断变化的气候条件下，降雨量的减少和 IOD 指数（IODI）的增加可能会加剧半干旱地区的缺水挑战。超过 70% 的分区 SO 分别与季风和季风后降雨呈正相关和负相关。这种矛盾在 PI Region 上尤为明显，导致 SO-AR 关系较弱。与 SO-降雨关系相比，在分区和区域降雨（季风和季风后）-IOD 关系的情况下观察到几乎相反的情况。SO-AR 关系显示了弱（1941-1970 和 1995-2016）和强（1871-1941 和 1970-1995）连接的时期。有趣的是，IOD-AR 关系的加强是 SO-AR 减弱的原因，反之亦然，尤其是在 1970 年后时期。