Sea ice in the Okhotsk Sea plays a significant role in global climate change. However, the history and mechanism of changes in sea ice spanning the last glacial cycle remain controversial. In this study, an 8.8 m core (LV55-40-1) was recovered from the southwestern Okhotsk Sea that contains a continuous sea ice record over the past ~110 kyr. The sand fraction and dropstones were used as ice-rafted debris proxies to reconstruct the history of sea ice variations over the last ~110 kyr and to determine the underlying causes on orbital and millennial timescales. Sea ice expansions occurred during MIS 5b, MIS 4, mid-MIS 3, and early MIS 1, which were controlled mainly by decreased autumn insolation on an orbital timescale. Superimposed on the orbital-scale changes, millennial-scale variations in sea ice were also observed, with 19 expansion events that coincided with cold Dansgaard-Oeschger stadials. Millennial scale sea ice variations were most likely controlled by both the Arctic oscillation (AO) and the East Asian summer monsoon (EASM). During periods of negative AO patterns, decreased air temperatures over the Okhotsk Sea caused more active sea ice formation. Such conditions could have been reinforced, by a reduced influence of warm advection at the surface of the Okhotsk Sea caused by decreased discharge from the Amur River that resulted from a weakened EASM during cold stadials.

中文翻译：

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末次间冰期以来鄂霍次克海西南部海冰的轨道和千年变化及其意义

鄂霍次克海的海冰在全球气候变化中扮演着重要角色。然而，跨越最后一次冰川周期的海冰变化的历史和机制仍然存在争议。在这项研究中，从鄂霍次克海西南部回收了一个 8.8 m 的岩心 (LV55-40-1)，其中包含过去 ~110 kyr 的连续海冰记录。沙子部分和落石被用作冰筏碎片代理，以重建过去~110 kyr 海冰变化的历史，并确定轨道和千年时间尺度上的根本原因。海冰扩张发生在 MIS 5b、MIS 4、MIS 3 中期和 MIS 1 早期，主要受轨道时间尺度上秋季日照减少的控制。叠加在轨道尺度变化上，还观察到海冰千年尺度的变化，有 19 个扩展事件与寒冷的 Dansgaard-Oeschger 体育场同时进行。千年尺度的海冰变化很可能同时受北极振荡（AO）和东亚夏季风（EASM）的控制。在负 AO 模式期间，鄂霍次克海上空的气温降低导致更活跃的海冰形成。鄂霍次克海海面暖平流的影响减少，这种情况可能会得到加强，这是由于冷场期间EASM减弱导致阿穆尔河的流量减少。鄂霍次克海的气温下降导致更活跃的海冰形成。鄂霍次克海海面暖平流的影响减少，这种情况可能会得到加强，这是由于冷场期间EASM减弱导致阿穆尔河的流量减少。鄂霍次克海的气温下降导致更活跃的海冰形成。鄂霍次克海海面暖平流的影响减少，这种情况可能会得到加强，这是由于冷场期间EASM减弱导致阿穆尔河的流量减少。