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Abstract:
The study examines the interannual relationship between the variability of sea ice extent in the Indian Ocean sector (20–90oE) and Indian summer monsoon rainfall under the influence of Mascarene High. Sea ice extent during April-May-June (AMJ) appears to have a significant correlation with the summer monsoon rainfall over the Peninsular India region during June-July-August-September from 1979 to 2013. We utilized reanalysis, satellite, and in-situ observation data from 1979 to 2013. The empirical orthogonal function (EOF) and correlation analysis show that the first and third modes of principal component (PC1 and PC3) of SIE in the Indian Ocean sector during April-May-June (AMJ) are significantly correlated with the second mode of principal component (PC2) of Indian summer monsoon rainfall. The reanalysis data revealed that the changes in the SIE in the Indian Ocean sector excite meridional wave train responses along the Indian Ocean for both principal component modes. Positive (negative) SIE anomalies based on first and third EOFs (EOF1 and EOF3) contribute to the strengthening (weakening) of the Polar, Ferrel, and Hadley cells, inducing stronger (weaker) convective activity over the Indian latitudes. The weak (strong) convective activity over the Indian region leads to less (more) rainfall over the region during low (high) sea ice phase years. Furthermore, a weaker (stronger) polar jet during the low (high) sea ice phase is also noted.
