气候变化领域集成服务门户(CCPortal): Early Eocene vigorous ocean overturning and its contribution to a warm Southern Ocean

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DOI	10.5194/cp-16-1263-2020
	Early Eocene vigorous ocean overturning and its contribution to a warm Southern Ocean
	Zhang Y.; Huck T.; Lique C.; Donnadieu Y.; Ladant J.-B.; Rabineau M.; Aslanian D.
发表日期	2020
ISSN	18149324
起始页码	1263
结束页码	1283
卷号	16 期号:4
英文摘要	The early Eocene (∼ 55 Ma) was the warmest period of the Cenozoic and was most likely characterized by extremely high atmospheric CO2 concentrations. Here, we analyze simulations of the early Eocene performed with the IPSL-CM5A2 Earth system model, set up with paleogeographic reconstructions of this period from the DeepMIP project and with different levels of atmospheric CO2. When compared with proxy-based reconstructions, the simulations reasonably capture both the reconstructed amplitude and pattern of early Eocene sea surface temperature. A comparison with simulations of modern conditions allows us to explore the changes in ocean circulation and the resulting ocean meridional heat transport. At a CO2 level of 840 ppm, the early Eocene simulation is characterized by a strong abyssal overturning circulation in the Southern Hemisphere (40 Sv at 60 S), fed by deepwater formation in the three sectors of the Southern Ocean. Deep convection in the Southern Ocean is favored by the closed Drake and Tasmanian passages, which provide western boundaries for the buildup of strong subpolar gyres in the Weddell and Ross seas, in the middle of which convection develops. The strong overturning circulation, associated with subpolar gyres, sustains the poleward advection of saline subtropical water to the convective regions in the Southern Ocean, thereby maintaining deepwater formation. This salt-advection feedback mechanism is akin to that responsible for the present-day North Atlantic overturning circulation. The strong abyssal overturning circulation in the 55Ma simulations primarily results in an enhanced poleward ocean heat transport by 0.3-0.7PW in the Southern Hemisphere compared to modern conditions, reaching 1.7PW southward at 20° S, and contributes to keeping the Southern Ocean and Antarctica warm in the Eocene. Simulations with different atmospheric CO2 levels show that ocean circulation and heat transport are relatively insensitive to CO2 doubling. © 2020 Author(s).
语种	英语
scopus关键词	advection; atmospheric chemistry; carbon dioxide; concentration (composition); Eocene; feedback mechanism; heat transfer; overturn; paleogeography; proxy climate record; reconstruction; sea surface temperature; Southern Hemisphere; Antarctica; Atlantic Ocean; Atlantic Ocean (North); Atlantic Ocean (North); Australia; Drake Passage; Southern Ocean; Tasmania
来源期刊	Climate of the Past
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/146694
作者单位	Univ Brest, CNRS, IRD, Ifremer, Laboratoire d'Oceánographie Physique et Spatiale (LOPS), IUEM, Brest, France; Laboratoire des Sciences du Climat et de l'Environnement, LSCE-IPSL, CEA, CNRS, UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France; Aix Marseille Univ, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence, France; Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, United States; CNRS, Univ Brest, Univ Bretagne Sud, Laboratoire Geósciences Oceán (LGO, UMR6538), IUEM, Plouzané, France; Ifremer, Unité de Recherche Geósciences Marines, Centre de Bretagne, Plouzané, France
推荐引用方式 GB/T 7714	Zhang Y.,Huck T.,Lique C.,et al. Early Eocene vigorous ocean overturning and its contribution to a warm Southern Ocean[J],2020,16(4).
APA	Zhang Y..,Huck T..,Lique C..,Donnadieu Y..,Ladant J.-B..,...&Aslanian D..(2020).Early Eocene vigorous ocean overturning and its contribution to a warm Southern Ocean.Climate of the Past,16(4).
MLA	Zhang Y.,et al."Early Eocene vigorous ocean overturning and its contribution to a warm Southern Ocean".Climate of the Past 16.4(2020).