气候变化领域集成服务门户(CCPortal): A stronger versus weaker Walker: understanding model differences in fast and slow tropical Pacific responses to global warming

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DOI	10.1007/s00382-021-05818-5
	A stronger versus weaker Walker: understanding model differences in fast and slow tropical Pacific responses to global warming
	Heede U.K.; Fedorov A.V.; Burls N.J.
发表日期	2021
ISSN	0930-7575
起始页码	227
结束页码	243
英文摘要	The tropical Pacific response to radiative forcing remains uncertain as projected future changes to the Walker circulation and SST patterns vary substantially among climate models. Here, we study what sets the magnitude and timescales of the response and why they differ across models. Specifically, we compare the fast and slow responses of the tropical Pacific to abrupt CO2 increases (2, 4, 8, 16 × CO2) in two configurations of the same model family (CESM) that differ in horizontal resolution and mean biases. We find that the model with a higher resolution shows a transient ocean thermostat-like response to CO2-forcing, with a stronger Walker cell and lack of warming in the eastern Pacific trade wind belts. This fast response lasts for about 50 years and is followed by a slight Walker cell weakening and equatorial warming. The second model, with a coarser resolution, shows a weak and short-lasting ocean thermostat response, followed by pronounced Walker cell weakening and eastern equatorial Pacific warming, similar to the long-term pattern noted in previous studies. These fast and slow responses also manifest in experiments where CO2 is gradually increased. We relate the magnitude of the fast ocean-thermostat response to the structure of the equatorial thermocline, setting the strength of the Bjerknes feedback. The magnitude and timing of the delayed eastern equatorial Pacific warming are related to the competition of positive feedbacks amplifying the ocean thermostat against the effect of ocean subsurface warming eroding the thermostat. The latter effect is further amplified by the slowdown of oceanic subtropical cells and enhanced extra-tropical warming. Different balances between these effects could explain the large spread in the model future projections for the tropical Pacific. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/183433
作者单位	Department of Earth and Planetary Sciences, Yale University, 210 Whitney Avenue, New Haven, CT 06511, United States; LOCEAN/IPSL, Sorbonne University, Paris, France; Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, Fairfax, VA, United States
推荐引用方式 GB/T 7714	Heede U.K.,Fedorov A.V.,Burls N.J.. A stronger versus weaker Walker: understanding model differences in fast and slow tropical Pacific responses to global warming[J],2021.
APA	Heede U.K.,Fedorov A.V.,&Burls N.J..(2021).A stronger versus weaker Walker: understanding model differences in fast and slow tropical Pacific responses to global warming.Climate Dynamics.
MLA	Heede U.K.,et al."A stronger versus weaker Walker: understanding model differences in fast and slow tropical Pacific responses to global warming".Climate Dynamics (2021).