Alkenone data from ODP Hole 162-983C@en

Alkenone data from ODP Site 983 (UK37, UK'37 and %C37:4) spanning the 0.5-1.5 Ma interval, used to reconstruct sea surface temperatures and polar water mass expansion during the mid-Pleistocene transition (MPT). Past surface ocean circulation changes associated with the mid‐Pleistocene transition, 0.9-0.6 Ma, were reconstructed in the northern North Atlantic (ODP 983) using proxies for subarctic/subpolar water mass distributions (%C37:4 alkenone) and sea surface temperature (UK37, UK'37). A secular expansion of subarctic waters occurred from ∼1.15 Ma, spanning both glacial and interglacial intervals. After 0.9 Ma, low %C37:4 at Site 983 records a northward retreat of subarctic waters during interglacials in the Atlantic, while continued high glacial %C37:4 indicate extensive subarctic waters during glacial maxima associated with the development of the larger late Pleistocene ice sheets. It is proposed that the expansion of subarctic waters between 1.15 and 0.9 Ma exerted negative feedbacks to the moisture supply to the ice sheet source regions and may account for the apparent delayed ice sheet response to atmosphere‐ocean circulation changes associated with the mid‐Pleistocene transition that began as early as 1.2 Ma.本数据集包含大洋钻探计划（Ocean Drilling Program, ODP）983站位的烯酮（alkenone）数据，覆盖0.5至1.5百万年的时间区间，涉及的指标包括UK37、UK'37以及%C37:4，可用于重建中更新世转型期（mid-Pleistocene Transition, MPT）期间的海表温度与极地水团扩张演化情况。针对0.9至0.6百万年的中更新世转型期相关的古表层海洋环流变化，研究团队通过亚北极/副极地水团分布代用指标（%C37:4烯酮）与海表温度代用指标（UK37、UK'37），在北大西洋北部的ODP 983站位完成了相关古环境重建工作。约1.15百万年以来，亚北极水团发生长期持续扩张，覆盖了冰期与间冰期所有时段。0.9百万年之后，983站位较低的%C37:4值记录了大西洋间冰期内亚北极水团的北撤现象；而冰期持续偏高的%C37:4值则表明，在与大规模晚更新世冰盖发育相关的冰盛期（glacial maxima）内，亚北极水团的分布范围显著扩张。研究提出，1.15至0.9百万年期间亚北极水团的扩张对冰盖源区的水汽供应产生了负反馈效应，这或许可以解释为何冰盖对早至1.2百万年就已启动的中更新世转型期海气环流变化的响应出现明显延迟。