Yeh, S.-W.,Y.-J. Kang, Y. Noh and A. J. Miller, 2011:

The North Pacific climate transitions of the winters of 1976/77 and 1988/89

Journal of Climate, 24, 1170-1183.

Abstract. We examine characteristic changes in North Pacific sea surface temperature (SST) variability during the boreal winter (December-January-February) for two subperiods (1956-88 and 1977-2009) during which the 1976-77 and the 1988-89 climate transitions occurred. It is found that the Pacific Decadal Oscillation (PDO)-like SST variability plays a dominant role in the 1976-77 climate transition, while both the North Pacific Gyre Oscillation (NPGO)-like and PDO-like SST variability contribute to the 1988-89 climate transition. Furthermore, the leading mode changes from PDOlike SST variability in 1956-88 to NPGO-like SST variability in 1977-2009, indicative of an enhancement of NPGO-like SST variability since 1988. Changes in sea level pressure across the 1976-77 climate transition project strongly onto the Aleutian low pressure system. But sea level pressure changes across the 1988-89 climate transition project primarily onto the North Pacific Oscillation, which is associated with remote changes in the Arctic Oscillation over the polar region, as well. This contributes to enhancing the NPGO-like SST variability after 1988. We also analyze the output from an ensemble of TOGA experiments in which the observed SSTs are inserted only at grid points in the tropics between 20.S and 20.N. The results indicate that the changes in the North Pacific atmosphere in the 1976-77 climate transition are mostly due to the tropics, whereas those in the 1988-89 climate transition are not.

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