Short-term impacts of enhanced Greenland freshwater fluxes in an eddy-permitting ocean model
Short-term impacts of enhanced Greenland freshwater fluxes in an eddy-permitting ocean model
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DOI：
10.5194/os-6-749-2010
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发表时间：
2010-01-01
期刊：
影响因子：
3.2
通讯作者：
Aksenov, Y.
中科院分区：
文献类型：
--
作者：
Marsh, R.;Desbruyeres, D.;Aksenov, Y.
在一个敏感性实验中，一个允许涡旋的海洋环流模型被迫与现实的淡水通量从格陵兰冰盖，平均为1991-2000年期间。通量得到的质量平衡模型的冰盖，被迫与ERA-40再分析数据集。淡水通量分布在格陵兰岛周围，作为规定径流中的附加项，代表冰盖的季节性融化和固定的全年冰山崩解通量，为8.5个模型年。通过添加格陵兰淡水通量与现实的地理分布和季节性，实验的目的是调查海洋的响应突然和空间/时间均匀放大冰盖融化和排放，而不是本地化或逐渐变化的淡水通量。通过比较敏感性实验和控制实验，没有额外的通量对区域水文和环流的影响进行了研究。到敏感性实验结束时，大部分额外的淡水已经积累在巴芬湾，只有一小部分已经到达拉布拉多海的内部，那里的冬季混合层深度对盐度的微小变化很敏感。因此，对大规模环流的影响非常轻微。格陵兰西海岸强烈的清新作用的间接影响是对格陵兰周围环流的一个小的反气旋成分，它与风力驱动的气旋环流相反，并使通过加拿大群岛的净南向气流减少了约10%。对2000年后格陵兰质量损失加速的影响进行了讨论。
In a sensitivity experiment, an eddy-permitting ocean general circulation model is forced with realistic freshwater fluxes from the Greenland Ice Sheet, averaged for the period 1991-2000. The fluxes are obtained with a mass balance model for the ice sheet, forced with the ERA-40 reanalysis dataset. The freshwater flux is distributed around Greenland as an additional term in prescribed runoff, representing seasonal melting of the ice sheet and a fixed year-round iceberg calving flux, for 8.5 model years. By adding Greenland freshwater fluxes with realistic geographical distribution and seasonality, the experiment is designed to investigate the oceanic response to a sudden and spatially/temporally uniform amplification of ice sheet melting and discharge, rather than localized or gradual changes in freshwater flux. The impacts on regional hydrography and circulation are investigated by comparing the sensitivity experiment to a control experiment, without additional fluxes. By the end of the sensitivity experiment, the majority of additional fresh water has accumulated in Baffin Bay, and only a small fraction has reached the interior of the Labrador Sea, where winter mixed layer depth is sensitive to small changes in salinity. As a consequence, the impact on large-scale circulation is very slight. An indirect impact of strong freshening off the west coast of Greenland is a small anti-cyclonic component to the circulation around Greenland, which opposes the wind-driven cyclonic circulation and reduces net southward flow through the Canadian Archipelago by similar to 10%. Implications for the post-2000 acceleration of Greenland mass loss are discussed.