Impacts of the Atlantic warm pool on North American precipitation and global sea surface temperature in a coupled genera
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Impacts of the Atlantic warm pool on North American precipitation and global sea surface temperature in a coupled general circulation model Chunzai Wang1,2,3 · Sheng Chen1,2,3 · Zhenya Song4,5 · Xin Wang1,2,3 Received: 26 July 2020 / Accepted: 6 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The responses of North American precipitation to the Atlantic warm pool (AWP) are investigated by using observational data and the NCAR Community Earth System Model. We show that the responses are controlled by different physical mechanisms in different seasons. In the warm season, a large AWP reduces the North Atlantic subtropical high, consistent with Gill’s physics. The corresponding influence over North America is northerly wind anomalies in the lower atmosphere, which leads to a precipitation suppression in the central United States. However, in the cold season the AWP’s impact on North American precipitation is operated via the teleconnection of cold SST anomalies in the tropical Pacific which are induced by the AWP. A large AWP enhances the local Hadley circulation that moves across the equator to the tropical southeastern Pacific in the boreal summer. This inter-hemispheric process strengthens the atmospheric sinking and then increases the South Pacific subtropical high, resulting in the enhancement of the surface easterly trade wind and thus cold SST anomalies in tropical southeastern Pacific. The wind-evaporation-SST and Bjerknes feedbacks further lead tropical central Pacific SST to a La Niña-like pattern, which is consistent with that the significant and negative correlation between ENSO and the AWP is observed after the 1990s when the AWP leads by 6–9 months. The AWP-induced La Niña-like SST anomalies in the tropical central Pacific further prompts a negative phase of the Pacific North American teleconnection, resulting in decreased precipitation over the southern United States; and vice versa. In addition to the AWP-induced central Pacific-type of ENSO events, the paper also shows the influences of the AWP on SSTs in the North Pacific and Indian Oceans.
1 Introduction
* Chunzai Wang [email protected] * Sheng Chen [email protected] 1
State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
2
Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
3
Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou, China
4
First Institute of Oceanography, Ministry of Natural Resources, Qingdao, China
5
Key Laboratory of Marine Science and Numerical Modeling, Ministry of Natural Resources, Qingdao, China
The American West, northern Mexico and central United States have subjected severe droughts (e.g., Seager 2007, Seager et al. 2009; Hoerling et al. 2014), which largely influence people’s normal life and cause a lot of economical loss. Using output from climate models in the Intergovernmenta
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