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首页> 外文期刊>Paleoceanography >Persistent climatic and oceanographic oscillations in the subpolar North Atlantic during the MIS 6 glaciation and MIS 5 interglacial
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Persistent climatic and oceanographic oscillations in the subpolar North Atlantic during the MIS 6 glaciation and MIS 5 interglacial

机译：MIS 6冰川期和MIS 5冰川间期在北极亚极持续的气候和海洋振荡

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摘要

Rapidly accumulating sediments from the Bjorn drift deposit south of Iceland are studied for comparison of glacial/interglacial climate changes related to millennial variability of the subpolar surface and deep ocean circulation in the North Atlantic. High-resolution faunal, isotopic, and sedimentary analyses reveal a strong multimillennial climatic variability interpreted as oscillations in heat transport westward south of Iceland during marine isotope stage 6 (MIS 6), possibly related to the strength of the subpolar gyre (SPG). The oscillations persisted from MIS 6 through the following interglacial (MIS 5), although with diminished magnitude, and were respectively characterized by repeated advances of the polar front south of Iceland during MIS 6 and southward migrations of the Arctic front due to cold surface outflow through the East Greenland and East Iceland Currents during MIS 5. Incursions of cold, fresh surface waters, and drifting ice affected the dynamics of the SPG, episodically causing it to weaken and contract to the northwest. During these intervals of diminished SPG, the northward transport of subtropical heat and salt was strengthened and preferentially conveyed to the northeast past Iceland, enhancing deep-water formation in the Nordic Seas. By contrast, when the SPG was strong, more subtropical water and its associated heat were entrained within the relatively warm Irminger Current flowing westward south of Iceland. These oceanographic oscillations were associated with repeated multimillennial cooling and warming episodes during the glacial stage MIS 6, equivalent to the Dansgaard-Oeschger cycles of the last glaciation.
机译：对冰岛南部比约恩（Bjorn）漂流沉积物快速积聚的沉积物进行了研究，以比较与北大西洋次极地表的千年变化和深海环流有关的冰川/冰川间气候变化。高分辨率动物区系，同位素和沉积分析揭示了很强的跨千年气候变率，其解释为在海洋同位素第6阶段（MIS 6）期间冰岛向南以西传热的振荡，可能与亚极地回旋（SPG）的强度有关。 MIS 6的震荡一直持续到随后的冰间期（MIS 5），尽管幅度减小，并分别以MIS 6期间冰岛南部极地锋的反复不断前进和由于冷面流出而导致北极锋向南迁移的特征为特征。 MIS 5期间东部格陵兰岛和冰岛东部海流的涌入。寒冷，新鲜的地表水和流冰的入侵影响了SPG的动力，从而使SPG减弱并向西北收缩。在SPG减少的这段时间里，亚热带热量和盐分的北向输送得到了加强，并被优先输送到冰岛东北部，从而增强了北欧海域的深水形成。相比之下，当SPG较强时，更多的亚热带水及其伴生的热量被夹带在冰岛南部以西的相对温暖的艾明格海流中。这些海洋振荡与冰川期MIS 6期间反复的千禧年降温和变暖事件有关，这相当于最后一次冰期的Dansgaard-Oeschger周期。

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