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DOI	10.5194/cp-15-1939-2019
	A South Atlantic island record uncovers shifts in westerlies and hydroclimate during the last glacial
	Björck S.; Sjolte J.; Ljung K.; Adolphi F.; Flower R.; Smittenberg R.H.; Kylander M.E.; Stocker T.F.; Holmgren S.; Jiang H.; Muscheler R.; Afrifa Y.K.K.; Rattray J.E.; Van Der Putten N.
发表日期	2019
ISSN	18149324
起始页码	1939
结束页码	1958
卷号	15 期号:6
英文摘要	Changes in the latitudinal position and strength of the Southern Hemisphere westerlies (SHW) are thought to be tightly coupled to important climate processes, such as cross-equatorial heat fluxes, Atlantic Meridional Overturning Circulation (AMOC), the bipolar seesaw, Southern Ocean ventilation and atmospheric CO2 levels. However, many uncertainties regarding magnitude, direction, and causes and effects of past SHW shifts still exist due to lack of suitable sites and scarcity of information on SHW dynamics, especially from the last glacial. Here we present a detailed hydroclimate multiproxy record from a 36.4-18.6 kyr old lake sediment sequence on Nightingale Island (NI). It is strategically located at 37ĝF S in the central South Atlantic (SA) within the SHW belt and situated just north of the marine Subtropical Front (SF). This has enabled us to assess hydroclimate changes and their link to the regional climate development as well as to large-scale climate events in polar ice cores. The NI record exhibits a continuous impact of the SHW, recording shifts in both position and strength, and between 36 and 31 ka the westerlies show high latitudinal and strength-wise variability possibly linked to the bipolar seesaw. This was followed by 4 kyr of slightly falling temperatures, decreasing humidity and fairly southerly westerlies. After 27 ka temperatures decreased 3-4 ĝC, marking the largest hydroclimate change with drier conditions and a variable SHW position. We note that periods with more intense and southerly-positioned SHW seem to be related to periods of increased CO2 outgassing from the ocean, while changes in the cross-equatorial gradient during large northern temperature changes appear as the driving mechanism for the SHW shifts. Together with coeval shifts of the South Pacific westerlies, our results show that most of the Southern Hemisphere experienced simultaneous atmospheric circulation changes during the latter part of the last glacial. Finally we can conclude that multiproxy lake records from oceanic islands have the potential to record atmospheric variability coupled to large-scale climate shifts over vast oceanic areas.. © 2019 All rights reserved.
语种	英语
scopus关键词	atmosphere-ocean coupling; heat flux; hydrometeorology; Last Glacial; latitudinal gradient; meridional circulation; regional climate; Southern Hemisphere; temperature gradient; westerly; Atlantic Ocean; Atlantic Ocean (South); Nightingale Island; Pacific Ocean; Pacific Ocean (South); Saint Helena; Southern Ocean; Tristan da Cunha
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/146769
作者单位	Department of Geology, Lund University, Lund, 22362, Sweden; Department of Geological Sciences and the Bolin Centre for Climate Research, Stockholm University, Stockholm, 10691, Sweden; University of Bern, Physics Institute, Climate and Environmental Physics, Sidlerstrasse 5, Bern, 3012, Switzerland; Department of Geography, University College London, London, WC1E 6BT, United Kingdom; Key Laboratory of Geographic Information Science, East China Normal University, Shanghai, 200062, China; School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, B15 2TT, United Kingdom; Department of Biological Sciences, University of Calgary, Calgary, Canada; Earth and Climate Cluster, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, Netherlands; Oeschger Centre for Climate Change Research, University of Bern, Bern, 3012, Switzerland
推荐引用方式 GB/T 7714	Björck S.,Sjolte J.,Ljung K.,et al. A South Atlantic island record uncovers shifts in westerlies and hydroclimate during the last glacial[J],2019,15(6).
APA	Björck S..,Sjolte J..,Ljung K..,Adolphi F..,Flower R..,...&Van Der Putten N..(2019).A South Atlantic island record uncovers shifts in westerlies and hydroclimate during the last glacial.Climate of the Past,15(6).
MLA	Björck S.,et al."A South Atlantic island record uncovers shifts in westerlies and hydroclimate during the last glacial".Climate of the Past 15.6(2019).