Impact of Long‐Distance Interaction Indicator (Monsoon Indices) on Spatio‐Temporal Variability of Precipitation Over the Mahanadi River Basin

Abstract

AbstractThe variability of the Indian Summer Monsoon Rainfall (ISMR), lasting from June to September, has a major impact on the Indian economy and ecosystem. An attempt to assess the temporal fluctuation of ISMR with the long‐distance interaction indicators has been presented here. This also corroborates the argued statement of a weakening relationship between ISMR and Indian Summer Monsoon Index (ISMI) due to significant temporal fluctuation. Monsoon indices: the ISMI, East Asian Summer Monsoon Index (EASMI), South Asian Summer Monsoon Index (SASMI), and Western‐North Pacific Monsoon Index (WNPMI) have been studied to create a correlation, coherency, and teleconnection with the ISMR over the Mahanadi River basin (MRB) during 1948–2017. High‐resolution gridded precipitation data were employed to assess the statistical properties of the monsoon and to address the correlation, coherency, and teleconnection with the ISMR. Spearman's rank‐based correlation test, a non‐parametric Mann‐Kendall trend test, and Sen's slope have been used to assess the statistical properties of observed precipitation and the monsoon indices. Furthermore, wavelet transform coherence is used to detect transient correlations between ISMR and monsoon indices that have previously been uncorrelated. SASMI (ρ = 0.440) dominates ISMI (ρ = 0.422) as the most significant and influential long‐distance indicator with ISMR. The findings were reconfirmed on a sub‐basin scale, with the middle Mahanadi River Basin (MMRB) being the most significant and influential, whereas the upper Mahanadi River Basin and lower Mahanadi River Basin were the second and third most influential, respectively.