Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea
Contrasts in Arctic shelf sea-ice regimes and some implications: Beaufort Sea versus Laptev Sea
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北极陆架海冰状况的对比和一些影响：波弗特海与拉普捷夫海
DOI：
10.1016/0025-3227(94)90182-1
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
D. Nürnberg
中科院分区：
文献类型：
--
作者：
E. Reimnitz;D. Dethleff;D. Nürnberg
阿拉斯加博福特海陆架宽<80 km的冬季冰态的特征是压缩和剪切，导致形成主要的接地压力脊系统，稳定了陆架中部的快冰，基本上没有开放水域。相比之下，冬季冰制度的500公里宽的拉普捷夫海架是由风吹从陆地到海洋，因此是扩张。一个常年的冰间湖与数百个宽达数百米、非常光滑的近海坚冰接壤。在这片开放水域中，快速形成的冰不断被平均风场平流输送到近海，使拉普捷夫海成为北冰洋和跨极漂移的唯一主要冰工厂。相反，随着夏季变暖，这个黑暗的冰间湖变成了一个高热量的区域，这导致冰缘后退到比博福特海更高的纬度和更远的距离（>500公里）。因此，每年的冻结并不包括老的，深吃水的冰，并与缺乏压缩，这种深吃水的冰不会产生原位，如在博福特海架。拉普捷夫海有多达1000公里的提取在夏末，当冻结风暴移动和大（6米）的波浪可以形成。此外，在冬季的前三个月，冰间湖位于近海，水深仅为10米。与短程博福特海的条件相比，湍流和冻结是冰碛和锚冰夹带沉积物的绝佳条件。我们预计夹带每年发生一次。与博福特海陆架的冰凿作用不同，拉普捷夫海的底形可能以水力底形为主，与大量的冰生成相对应，拉普捷夫海生成了更多的浓水，可能伴随着下坡输沙。温盐对流在中陆架冰间湖，再加上冰龙骨的底部破坏率降低，可能会提高底栖生物的生产力，并允许建立开放式陆架底栖生物群落，在博福特海只能在屏障岛屿的保护下茁壮成长。海象也需要全年开放的水域，这是海底生物高生产力的间接证据。相比之下，缺乏合适的环境限制了海象从博福特海，虽然超过700公里远的南部。我们可以推测博福特海和拉普捷夫海不同冰态的其他后果，但这几个例子有助于指出从北美北极获得的知识扩展到其他浅北极大陆架环境的危险。
The winter ice-regime of the <80 km wide Alaskan Beaufort Sea shelf is characterized by compression and shearing, resulting in the formation of major grounded pressure ridge systems stabilizing the fast ice on the mid-shelf, and essentially no open-water areas. In contrast, the winter ice-regime of the 500-km wide Laptev Sea shelf is controlled by winds blowing from land to sea, and is therefore dilational. A perennial polynya borders the hundreds of kilometers-wide and very smooth fast ice offshore. In this body of open water, rapidly forming ice is continuously advected offshore by the mean wind field, making the Laptev Sea the single major ice factory for the Arctic Ocean and Transpolar Drift. Conversely, with summer warming this dark polynya turns into an area of high heat gain, which results in the retreat of the ice edge to a much higher latitude and greater distance (>500 km) from the mainland than in the Beaufort Sea. As a result, the annual freeze-up does not incorporate old, deep-draft ice, and with a lack of compression, such deep-draft ice is not generated in situ, as on the Beaufort Sea shelf.The Laptev Sea has as much as 1000 km of fetch at the end of summer, when freezing storms move in and large (6 m) waves can form. Also, for the first three winter months, the polynya lies inshore at a water depth of only 10 m. Turbulence and freezing are excellent conditions for sediment entrainment by frazil and anchor ice, when compared to conditions in the short-fetched Beaufort Sea. We expect entrainment to occur yearly. Different from the intensely ice-gouged Beaufort Sea shelf, hydraulic bedforms probably dominate in the Laptev Sea.Corresponding with the large volume of ice produced, more dense water is generated in the Laptev Sea, possibly accompanied by downslope sediment transport. Thermohaline convection at the midshelf polynya, together with the reduced rate of bottom disruption by ice keels, may enhance benthic productivity and permit establishment of open-shelf benthic communities which in the Beaufort Sea can thrive only in the protection of barrier islands. Indirect evidence for high benthic productivity is found in the presence of walrus, who also require year-round open water. By contrast, lack of a suitable environment restricts walrus from the Beaufort Sea, although over 700 km farther to the south. We could speculate on other consequences of the different ice regimes in the Beaufort and Laptev Seas, but these few examples serve to point out the dangers of exptrapolating from knowledge gained in the North American Arctic to other shallow Arctic shelf settings.