Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre
Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre
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DOI：
10.1038/ngeo1379
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发表时间：
2012-03-01
影响因子：
18.3
通讯作者：
Bacon, Sheldon
中科院分区：
文献类型：
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作者：
Giles, Katharine A.;Laxon, Seymour W.;Bacon, Sheldon
北冰洋的淡水收支包括河流径流、降水、蒸发、海冰以及与北太平洋和大西洋的交换(1)。超过7万公里的淡水储存在北冰洋的上层，导致北极上层海水的盐度较低，被强烈的盐跃层与下面温暖的咸水分开。空间和时间有限的观测表明，在过去几十年里，北冰洋的淡水含量增加了，主要是在西部（3-5）。模型表明，风驱动的辐合驱动淡水积累(6)。在这里，我们使用1995年至2010年间的连续卫星测量数据来显示，与北极西部波弗特环流相关的海面高度圆顶一直在变陡，表明环流在自旋上升。我们发现，风场旋度的趋势（风场旋度是衡量导致水辐合或辐散的空间梯度）呈现出相应的空间格局，表明风驱动的辐合控制着淡水的变化。我们估计北冰洋西部的淡水储藏量增加了8,000 +/- 2,000 km(3)，这与水文观测结果一致（4,5），并得出结论，风场的逆转可能导致波弗特环流的自旋下降，并将这些淡水释放到北冰洋。
The Arctic Ocean's freshwater budget comprises contributions from river runoff, precipitation, evaporation, sea-ice and exchanges with the North Pacific and Atlantic(1). More than 70,000 km(3) of freshwater(2) are stored in the upper layer of the Arctic Ocean, leading to low salinities in upper-layer Arctic sea water, separated by a strong halocline from warm, saline water beneath. Spatially and temporally limited observations show that the Arctic Ocean's freshwater content has increased over the past few decades, predominantly in the west(3-5). Models suggest that wind-driven convergence drives freshwater accumulation(6). Here we use continuous satellite measurements between 1995 and 2010 to show that the dome in sea surface height associated with the western Arctic Beaufort Gyre has been steepening, indicating spin-up of the gyre. We find that the trend in wind field curl-a measure of spatial gradients in the wind that lead to water convergence or divergence-exhibits a corresponding spatial pattern, suggesting that wind-driven convergence controls freshwater variability. We estimate an increase in freshwater storage of 8,000 +/- 2,000 km(3) in the western Arctic Ocean, in line with hydrographic observations(4,5), and conclude that a reversal in the wind field could lead to a spin-down of the Beaufort Gyre, and release of this freshwater to the Arctic Ocean.