The recent trends in the Indian summer monsoon rainfall

India gets maximum rain during the summer months of June through September, called Indian summer monsoon rainfall (ISMR). The increasing/decreasing trend of ISMR affects millions of agriculture-dependent people in India. The spatial deviation of long-term ISMR trends indicates the monsoon circulation shift and should be minutely observed. The current study has observed that the ISMR has statistically significantly increased/decreased in western/eastern India in the last four decades. The significance of these trends is checked by evaluating the incomplete beta function used as a p-Value calculator for the Student t-test. In the meantime, the Indian Ocean has become more active due to its recent warming. The warming of the equatorial Indian Ocean has increased the in-situ convection south of the equatorial Indian Ocean, whose subsidising Hadley’s branches has increased the upper-tropospheric geopotential height (GPH) in northern Europe and southern Africa. The north Europe GPH is associated with the Eurasian wave having massive ridges over eastern Europe and east Asia sandwiched with a trough east of the Caspian Sea. The penetration of this trough towards the Indian landmass has created favourable conditions for deep convection. Besides, the southern African GPH increases the cross-equatorial flow, which interacts with the mid-tropospheric trough over the Arabian Sea, increasing the moisture flow/convergence over western India. The interaction of the cross-equatorial flow with the upper-tropospheric penetrated trough through the Indian landmass increases the moist static energy, which results in heavy rainfall over west India and causes a shift of monsoon westward. This teleconnection could further be examined in the seasonal forecast models.