ENSO and PDO
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I don't have the answers to your questions at the moment - it would take a little digging. Based on this previous work (Fig. 3), the peak correlation between ENSO and the PDO is between 0.6 and 0.7, so it does leave a considerable amount of PDO variability (>50%) that is independent of ENSO. Still, I would think this winter's situation is unusual, but global sea surface temperatures in general have been very unusual over the past year.