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首页> 外文会议>NATO Advanced Research Workshop on the Freshwater Budget of the Arctic Ocean, Apr 27-May 1, 1998, Tallinn, Estonia >EXCHANGES OF FRESHWATER THROUGH THE SHALLOW STRAITS OF THE NORTH AMERICAN ARCTIC
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EXCHANGES OF FRESHWATER THROUGH THE SHALLOW STRAITS OF THE NORTH AMERICAN ARCTIC

机译：穿过北美北极浅海峡的淡水交换

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The shallow straits of the North American Arctic include Bering Strait, which connects the Pacific Ocean to the Arctic Ocean, and the myriad channels of the Canadian Arctic Archipelago, which connect the Arctic Ocean to the Atlantic. A net flux of freshwater passes from the North Pacific into the North Atlantic via these straits (plus Fram Strait), and thereby stabilizes a global imbalance in precipitation less evaporation between the two major ocean basins. At the same time, the fluctuating outflows of fresh Arctic waters into the Greenland Sea, via Fram Strait, and into the Labrador Sea, via the Canadian Arctic Archipelago, may control the occurrence of deep ocean convection in these areas. For these reasons, the freshwater fluxes through the shallow straits of the North American Arctic are important within the global climate system. To meet the needs of climate prediction, we need (a) to estimate to known accuracy the magnitudes of the present fluxes of freshwater through these straits, and their seasonal and interannual variations, and (b) to develop an understanding of the forcing of and controls on these fluxes. It is important to clarify the meaning of the term freshwater flux. Formally, the freshwater flux is the rate of transport of seawater mass, minus the rate of transport of the mass of salt contained within it. More intuitive, if less rigorous, is the freshwater anomaly flux. This is the volume flux of zero-salinity water that must be combined with a volume flux of reference-salinity water to yield the flux of seawater of the salinity observed. Imprecision associated with use of volume rather than mass in this definition is negligible relative to the inaccuracy of present estimates. Here we use freshwater flux to denote the latter concept. The choice of reference salinity is arbitrary. Here we use the convenient whole-number value 35, which approximates the maximum salinity within the Arctic basins. This reference yields a freshwater flux at typical Arctic surface-water salinity that is about 8% higher than the 34.8-reference used elsewhere. The difference is insignificant relative to present uncertainty in these fluxes. Past efforts to observe flows in the shallow straits of the North American Arctic have rightly concentrated on determining the fluxes of water volume, and their variations. Even the accuracy of volume-flux estimates is low, since few data are available. Measuring the fluxes of freshwater is a much greater challenge. According to the most recent estimates, by Aagaard and Carmack, the principal oceanic influx of freshwater (adjusted to reference salinity 35) to the Arctic is through Bering Strait (1800 km~3 y~(-1)). The major outflow is through Fram Strait (2800 km~3 y~(-1)) as ice, with an additional 1170 km~3 y~(-1) as water. These authors assess the freshwater outflow through the Canadian Arctic to be about the same as Fram Strait (1230 km~3 y~(-1)), but the ice outflow to be smaller (155 km~3 y~(-1)). Ingram and Prinsenberg derive a much larger value (7100 km~3 y~(-1)) for the Canadian freshwater outflow. Estimates of the net export south through Davis Strait into the Labrador Sea are intermediate, 3100 km~3 y~(-1) as water and 1100 km~3 y~(-1) as ice. Clearly, we are far from understanding the oceanic fluxes of freshwater in the Arctic. This paper will illustrate the observational basis of these preliminary estimates, and propose a more sophisticated context to guide future consideration of this issue.
机译：北美北极的浅海峡包括连接太平洋和北冰洋的白令海峡，以及连接北冰洋和大西洋的加拿大北极群岛的无数海峡。净淡水通量通过这些海峡（加上弗拉姆海峡）从北太平洋进入北大西洋，从而稳定了全球主要失衡，减少了两个主要海盆之间的蒸发。同时，波动的新鲜北极水经弗拉姆海峡流入格陵兰海，再经加拿大北极群岛流入拉布拉多海，可控制这些地区深海对流的发生。由于这些原因，在全球气候系统中，流经北美北极浅海峡的淡水流量非常重要。为了满足气候预测的需求，我们需要（a）以已知的精度估算目前通过这些海峡的淡水通量的大小，季节和年际变化，以及（b）了解对强迫的影响。控制这些通量。阐明术语淡水通量的含义很重要。形式上，淡水通量是海水质量的传输速率减去其中所含盐质量的传输速率。如果不那么严格，则更直观的是淡水异常通量。这是零盐度水的体积通量，必须将其与参考盐度水的体积通量相结合，以产生观察到的盐度海水通量。与当前估计的不准确性相比，在此定义中，与使用体积而不是质量相关的不精确度可以忽略不计。在这里，我们使用淡水通量来表示后一个概念。参考盐度的选择是任意的。在这里，我们使用方便的整数值35，它近似于北极盆地内的最大盐度。该参考文献在典型的北极地表水盐度下产生的淡水通量比其他地方使用的34.8参考文献高约8％。相对于这些通量中的当前不确定性而言，差异不明显。过去观测北美北极海峡水流的努力正确地集中在确定水量通量及其变化上。由于很少有可用数据，因此即使是流量估计的准确性也很低。测量淡水通量是一个更大的挑战。根据Aagaard和Carmack的最新估计，主要的海洋淡水（经参考盐度35调整后）流入白令海峡（1800 km〜3 y〜（-1））。主要流出量为冰流经弗拉姆海峡（2800 km〜3 y〜（-1）），另外还有1170 km〜3 y〜（-1）为水。这些作者估计通过加拿大北极的淡水流出量与Fram海峡大致相同（1230 km〜3 y〜（-1）），但冰流出量较小（155 km〜3 y〜（-1））。 。英格拉姆（Ingram）和普林森贝格（Prinsenberg）为加拿大的淡水流出量得出了一个更大的值（7100 km〜3 y〜（-1））。通过戴维斯海峡向南进入拉布拉多海的净出口估计为中间，水为3100 km〜3 y〜（-1），冰为1100 km〜3 y〜（-1）。显然，我们离了解北极淡水的海洋通量还很远。本文将说明这些初步估计的观察基础，并提出一个更复杂的背景来指导将来对该问题的考虑。

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