气候变化领域集成服务门户(CCPortal): Time Scales and Mechanisms for the Tropical Pacific Response to Global Warming: A Tug of War between the Ocean Thermostat and Weaker Walker

CCPortal

DOI	10.1175/JCLI-D-19-0690.1
	Time Scales and Mechanisms for the Tropical Pacific Response to Global Warming: A Tug of War between the Ocean Thermostat and Weaker Walker
	Heede U.K.; Fedorov A.V.; Burls N.J.
发表日期	2020
ISSN	0894-8755
起始页码	6101
结束页码	6118
卷号	33 期号:14
英文摘要	Different oceanic and atmospheric mechanisms have been proposed to describe the response of the tropical Pacific to global warming, yet large uncertainties persist on their relative importance and potential interaction. Here, we use idealized experiments forced with a wide range of both abrupt and gradual CO2 increases in a coupled climate model (CESM) together with a simplified box model to explore the interaction between, and time scales of, different mechanisms driving Walker circulation changes. We find a robust transient response to CO2 forcing across all simulations, lasting between 20 and 100 years, depending on how abruptly the system is perturbed. This initial response is characterized by the strengthening of the Indo-Pacific zonal SST gradient and a westward shift of the Walker cell. In contrast, the equilibrium response, emerging after 50-100 years, is characterized by a warmer cold tongue, reduced zonal winds, and a weaker Walker cell. The magnitude of the equilibrium response in the fully coupled model is set primarily by enhanced extratropical warming and weaker oceanic subtropical cells, reducing the supply of cold water to equatorial upwelling. In contrast, in the slab ocean simulations, the weakening of the Walker cell is more modest and driven by differential evaporative cooling along the equator. The ''weaker Walker'' mechanism implied by atmospheric energetics is also observed for the midtroposphere vertical velocity, but its surface manifestation is not robust. Correctly diagnosing the balance between these transient and equilibrium responses will improve understanding of ongoing and future climate change in the tropical Pacific. © 2020 American Meteorological Society. All rights reserved.
英文关键词	Carbon dioxide; Cells; Climate models; Cytology; Evaporative cooling systems; Global warming; Oceanography; Tropics; Coupled climate model; Different mechanisms; Equatorial upwelling; Evaporative cooling; Extratropical warming; Fully-coupled model; Surface manifestations; Walker circulation; Transient analysis; air-sea interaction; carbon dioxide; climate modeling; experimental study; global warming; sea surface temperature; temperature gradient; troposphere; Walker circulation; zonal wind; Pacific Ocean; Pacific Ocean (Tropical)
语种	英语
来源期刊	Journal of Climate
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/171225
作者单位	Department of Earth and Planetary Sciences, Yale University, New Haven, CT, 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.. Time Scales and Mechanisms for the Tropical Pacific Response to Global Warming: A Tug of War between the Ocean Thermostat and Weaker Walker[J],2020,33(14).
APA	Heede U.K.,Fedorov A.V.,&Burls N.J..(2020).Time Scales and Mechanisms for the Tropical Pacific Response to Global Warming: A Tug of War between the Ocean Thermostat and Weaker Walker.Journal of Climate,33(14).
MLA	Heede U.K.,et al."Time Scales and Mechanisms for the Tropical Pacific Response to Global Warming: A Tug of War between the Ocean Thermostat and Weaker Walker".Journal of Climate 33.14(2020).