Analysis of Decadal Climate Variability in the Tropical Pacific by Coupled GCM  

作　　者：ZHANG Ya-Le YU Yong-Qiang 

机构地区：[1]State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics （IAP）, Chinese Academy of Sciences, Beijing 100029, China [2]Gracluate University of the Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Atmospheric and Oceanic Science Letters》2011年第4期204-208,共5页大气和海洋科学快报（英文版）

基　　金：supported by the National Basic Research Program of China (973 program,Grant No.2010CB950502);the National Natural Science Foundation of China (Grant Nos.40975065 and 40821092)

摘　　要：This study presents the spatial and temporal structures of the decadal variability of the Pacific from an extended control run of a coupled global climate model (GCM).The GCM used was version-g2.0 of the Flexible Global Ocean Atmosphere Land System (FGOALS-g2.0) developed at LASG/IAP.The GCM FGOALS-g2.0 re-produces similar spatial-temporal structures of sea surface temperature (SST) as observed in the Pacific decadal os-cillation (PDO) with a significant period of approximately 14 years.Correspondingly,the PDO signals were closely related to the decadal change both in the upper-ocean temperature anomalies and in the atmospheric circulation.The present results suggest that warm SST anomalies along the equator relax the trade winds,causing the SSTs to warm even more in the eastern equatorial Pacific,which is a positive feedback.Meanwhile,warm SST anomalies along the equator force characteristic off-equa-torial wind stress curl anomalies,inducing much more poleward transport of heat,which is a negative feedback.The upper-ocean meridional heat transport,which is asso-ciated with the PDO phase transition,links the equatorial to the off-equatorial Pacific Ocean,acting as a major mechanism responsible for the tropical Pacific decadal variations.Therefore,the positive and negative feedbacks working together eventually result in the decadal oscilla-tion in the Pacific.This study presents the spatial and temporal structures of the decadal variability of the Pacific from an extended control run of a coupled global climate model （GCM）. The GCM used was version g2.0 of the Flexible Global Ocean Atmosphere Land System （FGOALS-g2.0） developed at LASG/IAP. The GCM FGOALS-g2.0 reproduces similar spatial-temporal structures of sea surface temperature （SST） as observed in the Pacific decadal oscillation （PDO） with a significant period of approximately 14 years. Correspondingly, the PDO signals were closely related to the decadal change both in the upper-ocean temperature anomalies and in the atmospheric circulation. The present results suggest that warm SST anomalies along the equator relax the trade winds, causing the SSTs to warm even more in the eastern equatorial Pacific, which is a positive feedback. Meanwhile, warm SST anomalies along the equator force characteristic off-equatorial wind stress curl anomalies, inducing much more poleward transport of heat, which is a negative feedback. The upper-ocean meridional heat transport, which is associated with the PDO phase transition, links the equatorial to the off-equatorial Pacific Ocean, acting as a major mechanism responsible for the tropical Pacific decadal variations. Therefore, the positive and negative feedbacks working together eventually result in the decadal oscillation in the Pacific.

关 键 词：Pacific decadal oscillation coupled GCM air-sea interaction meridional heat transport 

分 类 号：P732[天文地球—海洋科学] P467