Deciphering Long‐Distance Climate Interactions: A Teleconnection‐Based Analysis of Indian Summer Monsoon Variability

This study explores the variations in Indian summer monsoon rainfall (ISMR) and its substantial influence on India’s economic and ecological landscape. The research particularly focuses on the relationship between ISMR and several distant monsoon indices, including the “Indian Summer Monsoon Index (ISMI), East Asian Summer Monsoon Index (EASMI), South Asian Summer Monsoon Index (SASMI), and Western–North Pacific Monsoon Index (WNPMI).” Spanning from 1948 to 2017, the study uses high‐resolution gridded precipitation data to analyze correlations, coherence patterns, and teleconnections between ISMR and these indices. To capture the statistical characteristics of the monsoon, methodologies such as Spearman’s rank correlation, the Mann–Kendall trend test, Sen’s slope estimator, and wavelet transform coherence (WTC) analysis were applied. Results indicate that SASMI ( ρ = 0.539) stands out as a robust alternative long‐distance indicator, exhibiting stronger correlation with ISMR after ISMI ( ρ = 0.709). Notably, the Himalayan (Him) and North‐Eastern (NE) regions demonstrated heightened sensitivity to SASMI’s influence. The study further reveals a significant decline in monsoonal precipitation across India, with an average reduction of 0.652 mm/year. Drying trends are particularly pronounced in regions such as the Him (−0.976 mm/year; −0.131%/year), NE (−1.281 mm/year; −0.113%/year), West‐Central (WC; −0.772 mm/year; −0.074%/year), and Peninsular (Pen; −0.317 mm/year; −0.043%/year) areas. Conversely, a modest wetting trend (0.187 mm/year) is observed in the North‐Western (NW) region. Regional variations in rainfall patterns persist, with increased precipitation evident in the Western Ghats, WC, NE, and Eastern India, while other parts experience reduced rainfall. An essential finding of the study is the previously underestimated influence of SASMI on ISMR. Between 1971 and 2006, weak coherence patterns suggest a diminishing association between ISMR and ISMI, potentially attributed to climatic fluctuations and the overarching effects of climate change.