Atlantic Water advection to the eastern Fram Strait Multiproxy evidence for late Holocene variability
Atlantic Water advection to the eastern Fram Strait Multiproxy evidence for late Holocene variability
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DOI：
10.1016/j.palaeo.2011.05.030
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发表时间：
2011-08
期刊：
影响因子：
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通讯作者：
K. Werner;R. Spielhagen;D. Bauch;H. Hass;E. Kandiano;Katarzyna Zamelczyk
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文献类型：
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作者：
K. Werner;R. Spielhagen;D. Bauch;H. Hass;E. Kandiano;Katarzyna Zamelczyk
从斯瓦尔巴群岛西部的大陆边缘的AMS放射性碳测年的沉积物芯的多代理数据集显示，在过去的两千年的多年代际气候变率。对南极和底栖稳定同位素、南极有孔虫动物群和岩石成因参数的调查旨在通过强度、温度和盐度揭示大西洋水向东弗拉姆海峡的平流。在过去的2000年里，大西洋水一直存在于该地点。叠加在海冰/冰山的增加上，在公元1000年至1200年，在著名的中世纪气候异常（MCA）期间，检测到大西洋水流入和季节性无冰条件的强度加强。然而，MCA的温度从未超过世纪的温度。自公元1400年以来，冰筏碎片和高南极有孔虫通量的显着较高的部分表明，该网站位于季节性高度波动的海冰边缘的区域。公元800年前后和公元1730年之后，南极有孔虫通量急剧减少，表明夏季气候凉爽，海冰/冰山的影响很大。大量的亚极地南极有孔虫物种Turborotalia quinqueloba（尺寸为150-250μm）表明，在公元1860年之后，大西洋水已经加强流入弗拉姆海峡东部。然而，地表条件保持寒冷，直到世纪低南极有孔虫通量表明。最有可能的是在世纪初，小冰期结束时的寒冷条件在地表持续存在，而温暖和含盐的大西洋水已经加强，因此下沉到寒冷的上层混合层以下。具有高丰度的亚极地南极有孔虫的表层沉积物表明，在过去的几十年里，大西洋水的强烈流入为弗拉姆海峡东部提供了季节性的无冰条件。
A multiproxy data set of an AMS radiocarbon dated 46cm long sediment core from the continental margin off western Svalbard reveals multidecadal climatic variability during the past two millennia. Investigation of planktic and benthic stable isotopes, planktic foraminiferal fauna, and lithogenic parameters aims to unveil the Atlantic Water advection to the eastern Fram Strait by intensity, temperatures, and salinities. Atlantic Water has been continuously present at the site over the last 2000years. Superimposed on the increase in sea ice/icebergs, a strengthened intensity of Atlantic Water inflow and seasonal ice-free conditions were detected at ~1000 to 1200AD, during the well-known Medieval Climate Anomaly (MCA). However, temperatures of the MCA never exceeded those of the 20th century. Since ~1400AD significantly higher portions of ice rafted debris and high planktic foraminifer fluxes suggest that the site was located in the region of a seasonal highly fluctuating sea ice margin. A sharp reduction in planktic foraminifer fluxes around 800AD and after 1730AD indicates cool summer conditions with major influence of sea ice/icebergs. High amounts of the subpolar planktic foraminifer species Turborotalia quinqueloba in size fraction 150–250μm indicate strengthened Atlantic Water inflow to the eastern Fram Strait already after ~1860AD. Nevertheless surface conditions stayed cold well into the 20th century indicated by low planktic foraminiferal fluxes. Most likely at the beginning of the 20th century, cold conditions of the terminating Little Ice Age period persisted at the surface whereas warm and saline Atlantic Water already strengthened, hereby subsiding below the cold upper mixed layer. Surface sediments with high abundances of subpolar planktic foraminifers indicate a strong inflow of Atlantic Water providing seasonal ice-free conditions in the eastern Fram Strait during the last few decades.