Glacial–interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

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• 作者：Raquel A. Lopes dos Santos ; Matthias Prange ; Isla S. Castañ ; eda ; Enno Schefuß ; Stefan Mulitza ; Michael Schulz ; Eva M. Niedermeyer ; Jaap S. Sinninghe Damsté ; Stefan Schouten
• 关键词：U^K'₃₇ ; TEX₈₆ ; Atlantic meridional overturning circulation ; thermocline
• 刊名：Earth and Planetary Science Letters
• 出版年：2010
• 出版时间：1 December 2010
• 年：2010
• 卷：300
• 期：3-4
• 页码：407-414
• 全文大小：970 K

文摘

Changes in the strength of Atlantic meridional overturning circulation (AMOC) are known to have profound impacts on global climate. Coupled modelling studies have suggested that, on annual to multi-decadal time scales, a slowdown of AMOC causes a deepening of the thermocline in the tropical Atlantic. However, this process has been poorly constrained by sedimentary geochemical records. Here, we reconstruct surface (U^K'₃₇ Index) and thermocline (TEX^H₈₆) water temperatures from the Guinea Plateau Margin (Eastern tropical Atlantic) over the last two glacial–interglacial cycles (~ 192 kyr). These paleotemperature records show that periods of reduced AMOC, as indicated by the δ¹³ C benthic foraminiferal record from the same core, coincide with a reduction in the near-surface vertical temperature gradient, demonstrating for the first time that AMOC-induced tropical Atlantic thermocline adjustment exists on longer, millennial time scales. Modelling results support the interpretation of the geochemical records and show that thermocline adjustment is particularly pronounced in the eastern tropical Atlantic. Thus, variations in AMOC strength appear to be an important driver of the thermocline structure in the tropical Atlantic from annual to multi-millennial time scales.