| Summary: | This paper explores the three-way interactions between the Indian monsoon, the North Atlantic and the Tropical Pacific. Four climate records were analyzed: the monsoon rainfall in two Indian regions, the Southern Oscillation Index for the Tropical Pacific, and the NAO index for the North Atlantic. The individual records exhibit highly significant oscillatory modes with spectral peaks at 7–8 yr and in the quasi-biennial and quasi-quadrennial bands. The interactions between the three regions were investigated in the light of the synchronization theory of chaotic oscillators. The theory was applied here by combining multichannel singular spectrum analysis (M-SSA) with a recently introduced varimax rotation of the M-SSA eigenvectors. A key result is that the 7–8-yr and 2.7-yr oscillatory modes in all three regions are completely synchronized, and the energy ratio analysis suggests that the NAO induces these modes in the other two regions. Both these modes in the NAO appear to be connected to the intrinsic variability of the Gulf Stream front. It was found therewith that the South Asian monsoon is not slaved to forcing from the equatorial Pacific, although it does interact
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