The Labrador Sea is important for the modern global thermohaline circulation system through the formation of intermediate Labrador Sea Water (LSW) that has been hypothesized to stabilize the modern mode of North Atlantic deep-water circulation. The rate of LSW formation is controlled by the amount of winter heat loss to the atmosphere, the expanse of freshwater in the convection region and the inflow of saline waters from the Atlantic. The Labrador Sea, today, receives freshwater through the East and West Greenland currents (EGC, WGC) and the Labrador Current (LC). Several studies have suggested the WGC to be the main supplier of freshwater to the Labrador Sea, but the role of the southward flowing LC in Labrador Sea convection is still debated. At the same time, many paleoceanographic reconstructions from the Labrador Shelf focussed on late deglacial to early Holocene meltwater run-off from the Laurentide Ice Sheet (LIS), whereas little information exists about LC variability since the final melting of the LIS about 7000 years ago. In order to enable better assessment of the role of the LC in deep-water formation and its importance for Holocene climate variability in Atlantic Canada, this study presents high-resolution middle to late Holocene records of sea surface and bottom water temperatures, freshening, and sea ice cover on the Labrador Shelf during the last 6000 years. Our records reveal that the LC underwent three major oceanographic phases from the mid- to late Holocene. From 6.2 to 5.6 ka, the LC experienced a cold episode that was followed by warmer conditions between 5.6 and 2.1 ka, possibly associated with the late Holocene thermal maximum. While surface waters on the Labrador Shelf cooled gradually after 3 ka in response to the neoglaciation, Labrador Shelf subsurface or bottom waters show a shift to warmer temperatures after 2.1 ka. Although such an inverse stratification by cooling of surface and warming of subsurface waters on the Labrador Shelf would suggest a diminished convection during the last 2 millennia compared to the mid-Holocene, it remains difficult to assess whether hydrographic conditions in the LC have had a significant impact on Labrador Sea deep-water formation.

中文翻译：

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过去6000年中地表和地下拉布拉多陆架水的质量状况

拉布拉多海通过形成中间的拉布拉多海水（LSW）对现代全球热盐循环系统很重要，该水被假设为稳定北大西洋深水循环的现代模式。LSW的形成速率受冬季热量散失到大气中，对流区域中的淡水泛滥以及盐水从大西洋的流入控制。今天，拉布拉多海通过东西格陵兰洋流（EGC，WGC）和拉布拉多洋流（LC）接收淡水。多项研究表明，WGC将成为拉布拉多海淡水的主要供应者，但向南流动的LC在拉布拉多海对流中的作用仍存在争议。同时，拉布拉多大陆架的许多古海洋学重建都集中在Laurentide冰盖（LIS）的晚冰期到全新世早期融水径流，而自从LIS最终融化大约7000年前以来，关于LC变异性的信息很少。为了能够更好地评估LC在加拿大大西洋深水形成中的作用及其对全新世气候变化的重要性，本研究提供了高分辨率的中新世至晚全新世海面和底水温度记录，清新度和在过去的6000年中，拉布拉多架上的海冰覆盖了。我们的记录表明，从全新世中期到晚期，LC经历了三个主要的海洋学阶段。在6.2至5.6ka之间，LC经历了寒冷天气，随后温度升高到5.6至2.1ka之间，可能与晚全新世的热最大值有关。虽然拉布拉多架上的地表水在3ka之后响应新的冰河逐渐冷却，但拉布拉多架下层或底水在2.1ka之后显示向温暖的温度转变。尽管通过拉布拉多架地表的冷却和地下水的变暖进行的这种逆分层表明，与全新世中期相比，最近两千年期间的对流减少，但仍然难以评估LC的水文条件是否具有显着性。对拉布拉多海深水形成的影响。Labrador Shelf地下或底部水域在2.1？ka之后显示向温暖温度的转变。尽管通过拉布拉多架地表的冷却和地下水的变暖进行的这种逆分层表明，与全新世中期相比，最近两千年期间的对流减少，但仍然难以评估LC的水文条件是否具有显着性。对拉布拉多海深水形成的影响。Labrador Shelf地下或底部水域在2.1？ka之后显示向温暖温度的转变。尽管通过拉布拉多架地表的冷却和地下水的变暖进行的这种逆分层表明，与全新世中期相比，最近两千年期间的对流减少，但仍然难以评估LC的水文条件是否具有显着性。对拉布拉多海深水形成的影响。