Influence of the IOD on the Indian Monsoon Rainfall

Sliding correlation (11 years window) correlation between Indian Summer Monsoon Rainfall (ISMR) and Dipole Mode Index (Magenta) and Nino3 SSTA (Turquoise)

Ashok et al. (2001) identified influence of the Indian Ocean Dipole (IOD) on the interannual variability of the Indian summer monsoon rainfall (ISMR) for the period 1958-1997 (Ashok et al., 2001). The IOD and the ENSO have complementarily affected the ISMR during the last four decades. Whenever the ENSO-ISMR correlation is low (high), the IOD-ISMR correlation is high (low).  The IOD plays an important role as a modulator of the Indian monsoon rainfall and influences the correlation between the ISMR and ENSO. Ashok et al, using an AGCM, have discovered that the ENSO-induced anomalous circulation over the Indian region is either countered or supported by the IOD-induced anomalous meridional circulation cell, depending upon the phase and amplitude of the two major tropical phenomena in the Indo-Pacific sector.



Reference:

Ashok, K., Guan, Z., and T.Yamagata. Impact of the Indian Ocean Dipole on the relationship between the Indian monsoon rainfall and ENSO. 2001 Geophysical Research Letters, 28, 4499-4502 (Manuscript in pdf) (Figures in pdf)

 

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