Midlatitude circulation patterns associated with decadal and interannual Pacific Ocean variability

Abstract

The exact nature of the interaction between the Pacific Ocean and the climate of the Northern Hemisphere is still in large part uncertain. To investigate these interactions, canonical correlation analysis is applied to relate midlatitude atmospheric circulation variability with Pacific Ocean SST variability. The leading mode corresponds closely to decadal PDO‐like variability and the second mode is comparable to ENSO. Consequently, we identified different atmospheric circulation patterns related to the spatially similar, but temporally different modes of SST variability. Circulation variability over Eurasia is linked with the decadal SST variability, while the interannual SST variability is linked to circulation variability over the eastern Pacific. This suggests that decadal SST variability, in part, could be forced by the atmosphere. Furthermore, while the PDO switched back into its negative phase in the late 1990s, the decadal SST variability as related to circulation did not. Instead, the interannual mode has shifted into a negative phase, indicating a change in the nature of ocean‐atmosphere interaction in the late 1990s.