In the present paper, two methods are used to analyze the SST data from the ECMRWF and the NCEP/NCAR datasets. The first is a classical EOF (Empirical Orthogonal Function) analysis, which allows reconstructing the El-Nino, the La-Nina events with a good accuracy only by the first few EOF. However, the periods between these events need much more EOF for the reconstruction. The variability in midlatitudes is also not separated because of a strong signal in the tropics. Therefore, for the separation of these signals, the cluster method is used. The results obtained show that except a signal in the tropics, there exists a clearly marked signal in the subpolar gyre and the Kuroshio Extension with the inter-decadal modulation.

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