Cooling of the West Spitsbergen Current: Wintertime Observations West of Svalbard
Cooling of the West Spitsbergen Current: Wintertime Observations West of Svalbard
复制标题
西斯匹次卑尔根洋流变冷：斯瓦尔巴群岛以西的冬季观测
DOI：
10.1029/94jc01824
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发表时间：
1994
影响因子：
--
通讯作者：
E. D’Asaro
中科院分区：
文献类型：
--
作者：
T. Boyd;E. D’Asaro
西斯匹次卑尔根海流（WSC）是北冰洋和格陵兰海深层对流区热量和盐的主要来源。WSC洋流在下游急剧冷却。利用在斯匹次卑尔根岛进行的为期3周的隆冬航行的水文和速度数据，研究了WSC的热量收支和冷却机制。WSC中平均热通量的下游发散在电流宽度上平均产生至少1000±400 Wm−2的热损失。大约350 Wm−2被损耗到大气中，200 Wm−2被损耗到比洋流稍宽的区域融化的冰中。WSC对大气的冷却将流入的大西洋水（AW）转化为低北极中层水，这种水的盐度足以对流。冰的冷却作用将AW转化为更新鲜的北极地表水，这些水太轻而无法对流。这两种转换的相对重要性主要取决于风从巴伦支海将冰平流到WSC上空的速度。WSC最温暖的水通常在地表以下100-200米处。尽管缺乏与表面的直接接触，但在我们的观测中，这个温暖的核心在800 Wm−2左右冷却。这个速率太大了，不可能是由静脉扩散引起的。我们认为，该地区的高能涡旋场沿着连接暖核和地表的陡峭的等压面扩散热量，每天数次更新表层。这与观测到的浅层混合层和高侵入程度相一致。我们的结论是，大气和来自巴伦支海的冰冷却了WSC的表层，中尺度涡旋的等压流扩散不断地更新了该表面，从而冷却了WSC的内部。这些过程的相对强度决定了流入的暖的、含盐的水是转化为淡的、新鲜的地表水还是含盐的、冷的中间水。
The West Spitsbergen Current (WSC) is the major source of heat and salt for the Arctic Ocean and the areas of deep convection in the Greenland Sea. The WSC current cools dramatically downstream. Hydrographic and velocity data from a 3-week, midwinter cruise off Spitsbergen are used to investigate the heat budget of the WSC and the mechanisms of cooling. The downstream divergence of mean heat flux in the WSC produces a heat loss of at least 1000±400 Wm−2 averaged over the width of the current. Approximately 350 Wm−2 is lost to the atmosphere and 200 Wm−2 is lost to melting ice over a region somewhat wider than the current. Cooling of the WSC to the atmosphere converts the inflowing Atlantic Water (AW) to Lower Arctic Intermediate Water, which is sufficiently salty to convect. Cooling by ice converts the AW to much fresher Arctic Surface Water, which is too light to convect. The relative importance of these two conversions is primarily controlled by the rate at which the wind advects ice from the Barents Sea over the WSC. The warmest water of the WSC is often observed 100–200 m below the surface. Despite the lack of direct contact with the surface, this warm core cools at about 800 Wm−2 in our observations. This rate is too large to be caused by diapycnal diffusion. We suggest that the energetic eddy field in this area diffuses heat along the steeply sloping isopycnal surfaces that connect the warm core to the surface, renewing the surface layer several times per day. This is consistent with the very shallow surface mixed layers and high level of intrusions observed. We conclude that the surface layer of the WSC is cooled by the atmosphere and by ice from the Barents Sea and that isopycnal diffusion by mesoscale eddies continually renews this surface, thus cooling the interior of the WSC. The relative magnitude of these processes determines whether the inflowing warm, salty AW is converted to light, fresh surface water or salty, cold intermediate water.