Local and remote SST variability contribute to the westward shift of the Pacific Walker circulation during 1979–2015

Geoscience Letters

Chueh-Hsin Chang¹  Hailong Liu²  Xichen Li³  Xinyue Wang⁴  Wenzhu Wang⁴  Jiang Zhu⁴  Nathaniel C. Johnson⁵  Tao Lian⁶ 

[1] Center for Climate Change Prediction Research, Ewha Womans University, Seoul, South Korea;Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China;Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China;State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China;Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China;University of Chinese Academy of Sciences, Beijing, China;NOAA Geophysical Fluid Dynamics Laboratory, 08540, Princeton, NJ, USA;State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China;Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China;School of Oceanography, Shanghai Jiao Tong University, Shanghai, China;

关键词: Pacific Walker circulation;    Inter-basin interaction;    Atlantic multi-decadal oscillation;    Atmosphere–ocean interaction;   

DOI  :  10.1186/s40562-021-00180-0

来源: Springer

【 摘 要 】

During the modern satellite era since 1979, the Pacific Walker circulation (PWC) experienced an intensification and a westward shift, which has broad impacts on the global climate variability. While the strengthening of the PWC has been shown to be driven by both the regional Pacific sea surface temperature (SST) and the remote forcing from other basins, its westward shift is primarily attributed to the phase change of the Atlantic Multidecadal variability. In this study, we investigate the potential effect of the remote SST forcing from the Atlantic and the Indian Oceans on the westward shift of the PWC, through statistical analysis and numerical experiments using atmospheric and coupled models. Results show that the tropical Atlantic warming plays a key (decisive) role in driving the PWC westward shift by triggering a Gill–Matsuno-type circulation anomaly in the tropics. This circulation response drives anomalous surface westerlies over the eastern Pacific and subsidence over the central Pacific that weakens the eastern part of the PWC, meanwhile generating easterly wind anomalies over the central-western Pacific and anomalous atmospheric convection over the western Pacific that intensifies the western part of the PWC. This direct forcing contributes ~ 32% of the observed PWC movement, while the Atlantic-induced inter-basin SST changes contribute another ~ 36% of its westward shift according to coupled model simulation results. Our results reinforce the importance of the inter-basin interactions in adjusting the tropical climate variabilities, and have broad implication for projecting the global climate.

【 授权许可】

CC BY