Western tropical Pacific multidecadal variability forced by the Atlantic multidecadal oscillation

Cheng Sun,Fei-Fei Jin,In-Sik Kang,Fred Kucharski,Ruiqiang Ding,Jianping Li

doi:10.1038/ncomms15998

Abstract

Observational analysis suggests that the western tropical Pacific (WTP) sea surface temperature (SST) shows predominant variability over multidecadal time scales, which is unlikely to be explained by the Interdecadal Pacific Oscillation. Here we show that this variability is largely explained by the remote Atlantic multidecadal oscillation (AMO). A suite of Atlantic Pacemaker experiments successfully reproduces the WTP multidecadal variability and the AMO–WTP SST connection. The AMO warm SST anomaly generates an atmospheric teleconnection to the North Pacific, which weakens the Aleutian low and subtropical North Pacific westerlies. The wind changes induce a subtropical North Pacific SST warming through wind–evaporation–SST effect, and in response to this warming, the surface winds converge towards the subtropical North Pacific from the tropics, leading to anomalous cyclonic circulation and low pressure over the WTP region. The warm SST anomaly further develops due to the SST–sea level pressure–cloud–longwave radiation positive feedback. Our findings suggest that the Atlantic Ocean acts as a key pacemaker for the western Pacific decadal climate variability.

Highlights

Observational analysis suggests that the western tropical Pacific (WTP) sea surface temperature (SST) shows predominant variability over multidecadal time scales, which is unlikely to be explained by the Interdecadal Pacific Oscillation
The spectrum of detrended WTP SST is characterized by a high and significant concentration of variance at multidecadal time scales with a peak at quasi-60 years, indicating pronounced multidecadal variability over the WTP region
The observational analysis suggests that the WTP SST shows very strong multidecadal variability that is significantly correlated with the Atlantic multidecadal oscillation (AMO)

Summary

Introduction

Observational analysis suggests that the western tropical Pacific (WTP) sea surface temperature (SST) shows predominant variability over multidecadal time scales, which is unlikely to be explained by the Interdecadal Pacific Oscillation. Several studies have suggested that there is an Atlantic–Pacific connection at low-frequency time scales, but they have focused on the North Pacific decadal variability[33], the eastern Pacific response (or IPO-like pattern) to the Atlantic forcing[34,35], and the trend of the tropical atmosphere–ocean coupled system over recent decades[36,37,38].

Methods

Results

Conclusion