Oceanic heat pulses fueling moisture transport towards continental Europe across the mid-Pleistocene transition
Oceanic heat pulses fueling moisture transport towards continental Europe across the mid-Pleistocene transition
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DOI：
10.1016/j.quascirev.2017.11.009
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发表时间：
2018-01-01
影响因子：
4
通讯作者：
Friedrich, O.
中科院分区：
文献类型：
--
作者：
Bahr, A.;Kaboth, S.;Friedrich, O.
中更新世过渡期（MPT；约 1.2-0.7 Ma）的特点是北半球冰盖不断增长，冰期-间冰期周期从 41 kyr 转变为 100 kyr。随着大冰盖的增长，大气和海洋的环流格局也发生了变化。北大西洋的一个主要特征是风力驱动的副热带环流，它是欧洲大陆热量和湿气的主要提供者。在这里，我们研究了 MPT 期间副热带环流强度和空间结构的变化及其对大陆水分平衡的影响。为了重建副热带环流动力学，我们对伊比利亚边缘站点 U1385 的深部有孔虫 Globorotalia infata 进行了成对的 Delta O-18 和 Mg/Ca 分析，产生了 1400 至 500 ka 之间的温跃层温度 (T-therm) 变化。副热带环流的东部边界。U1385站点T-therm的长期趋势与MPT期间逐渐增强的冰川的北大西洋气候演化相反。特别是，MIS 20 和 18 冰川的标志是伊比利亚半岛附近温暖的温跃层水域。我们推断，（次）极锋向南移动使副热带环流内温跃层水域的源区从高纬度地区转移到中纬度地区。此外，MPT期间地中海出水量强劲，导致温暖的海水平流至伊比利亚半岛。欧洲东南部 MIS 20 和 18 期间的潮湿条件表明，来自这种温水的大气水分可能已被平流输送到欧洲大陆深处，并促进了高山冰川的生长。 (C) 2017 Elsevier Ltd. 保留所有权利。
The mid-Pleistocene Transition (MPT; approx. 1.2-0.7 Ma), is characterized by growing Northern Hemisphere ice sheets and the shift from a 41 kyr to a 100 kyr glacial-interglacial cyclicity. Concomitant to the growth of large ice sheets, atmospheric and oceanic circulation pattern have changed. One key feature of the North Atlantic is the wind-driven Subtropical Gyre, a major provider of heat and moisture for continental Europe. Here, we investigate changes in the strength and spatial configuration of the Subtropical Gyre during the MPT and its impact on the continental moisture balance.To reconstruct Subtropical Gyre dynamics, we conducted paired delta O-18 and Mg/Ca analyses on the deep-dwelling foraminifera Globorotalia inflata from Iberian Margin Site U1385 yielding thermocline temperature (T-therm) variability between 1400 and 500 ka at the eastern boundary of the Subtropical Gyre.Long-term trends of T-therm at Site U1385 oppose the North Atlantic climatic evolution of progressively intensified glacials during the MPT. Particularly, glacials MIS 20 and 18 were marked by warm thermocline waters off Iberia. We infer that a southward shift of the (sub)polar front displaced the source region of thermocline waters within the Subtropical Gyre from high to mid-latitudes. In addition, a strong Mediterranean Outflow Water production during the MPT caused the advection of warm waters to Iberia. Humid conditions during MIS 20 and 18 in SE Europe indicate that atmospheric moisture derived from this warm water might have been advected deep into continental Europe and contributed to enhanced growth of Alpine glaciers. (C) 2017 Elsevier Ltd. All rights reserved.