The Antarctic coastal current in the southeastern Weddell Sea
The Antarctic coastal current in the southeastern Weddell Sea
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威德尔海东南部的南极沿岸流
DOI：
10.1007/bf00238257
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发表时间：
1992
期刊：
影响因子：
1.7
通讯作者：
G. Krause
中科院分区：
文献类型：
--
作者：
E. Fahrbach;G. Rohardt;G. Krause
1989年1月至3月，在EPOS第3航段期间，在威德尔海东南部进行了一次水文测量，测量的断面横跨Kapp Norvegia和哈雷湾外的大陆架和斜坡。该数据集代表南极夏季的海洋学状况。冬季观测是在1989年9月和10月的冬季威德尔环流研究期间获得的。在夏季，表层水相对温暖，盐度低。哈雷湾地区遭遇异常温暖的天气，海面温度接近+1 ° C。在大陆坡上部，锋面区将东部陆架水与南极表层水（近表层）和温暖的深层水（深层）分开。与锋面相关的水平压力梯度产生了南极沿岸流的高速核心。在冬季，南极地表水被更冷的高盐度冬季水所取代。停泊在Kapp Norvegia和Vestkapp的海流计的测量值用于描述海流场及其波动的平均特征。在Kapp Norvegia，年平均流速为10至20厘米/秒。地转流切变表明，流核的速度向哈雷湾方向减小。海流具有明显的季节变化和年际差异。这些与Georg von Neumayer站观测到的风场变化相比较。叠加的是更高频率的波动，其能量范围在5到15天之间，这也在风测量中发现。海流速度变化的相当一部分是由潮汐引起的。海洋条件受当地海底地形的强烈影响。诺维吉亚角外陆架边缘的地形上升减少了水平平流，并允许一片寒冷的冬季水被保存到夏天。相比之下，在哈雷湾的陆架上发现了一片温暖的深水。这表明，由于与公海以及近表层的交换率不同，近底层的情况相当不均匀。
SummaryBetween January and March 1989 during EPOS leg 3, a hydrographic survey was carried out in the southeastern Weddell Sea on transects across the continental shelf and slope off Kapp Norvegia and Halley Bay. This data set represents oceanographic conditions during Antarctic summer. Winter observations were obtained during the Winter Weddell Gyre Study in September and October 1989. During summer the water in the surface layer is relatively warm and of low salinity. In the area of Halley Bay exceptionally warm conditions were encountered with sea surface temperatures of nearly +1°C. Over the upper continental slope a frontal zone separates Eastern Shelf Water from Antarctic Surface Water in the near surface layer and from Warm Deep Water in the deeper layers. The horizontal pressure gradient associated with the front produces the high velocity core of the Antarctic Coastal Current. In winter Antarctic Surface Water is replaced by colder Winter Water of higher salinity. Measurements from current meters moored off Kapp Norvegia and Vestkapp are used to describe the mean features of the current field and its fluctuations. At Kapp Norvegia annual mean current speeds range from 10 to 20 cm/s. The geostrophic current shear indicates that the speed of the current core decreases towards Halley Bay. The currents show significant seasonal variations with strong interannual differences. These compare well with the variations of the wind field observed at the Georg von Neumayer Station. Superimposed are higher frequency fluctuations with an energetic range between 5 and 15 days which is found in the wind measurements as well. A considerable part of the current velocity variance is due to the tides. The oceanographic conditions are strongly influenced by the local bottom topography. A topographic rise at the shelf edge off Kapp Norvegia reduces horizontal advection and allows a patch of cold Winter Water to be preserved into the summer. In contrast, a patch of Warm Deep Water was found on the shelf of Halley Bay. This illustrates rather heterogeneous conditions in the near bottom layers due to differences in the exchange rate with the open ocean as well as with the near surface layers.