AN ARCTIC SOURCE FOR THE GREAT SALINITY ANOMALY - A SIMULATION OF THE ARCTIC ICE-OCEAN SYSTEM FOR 1955-1975
AN ARCTIC SOURCE FOR THE GREAT SALINITY ANOMALY - A SIMULATION OF THE ARCTIC ICE-OCEAN SYSTEM FOR 1955-1975
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DOI：
10.1029/93jc01504
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发表时间：
1993-09-15
影响因子：
3.6
通讯作者：
HAKKINEN, S
中科院分区：
文献类型：
--
作者：
HAKKINEN, S
一个完全预报北极冰-海模式被用来研究1955-1975年期间海冰的年际变化，并解释了20世纪60年代后期格陵兰和冰岛海冰范围的大变化。特别是，该模型被用来检验Aagaard和Carmack（1989）的猜想，即大盐度异常（GSA）是1968年大量冰输出的结果。本文的目的是探讨风场变化对高纬冰洋环流的影响。在模拟中，格陵兰海的冰范围在20世纪60年代增加，在1968年达到最大值，正如观察到的那样，冰范围的最大值总是在通过弗拉姆海峡的冰输出的大脉冲之前。1968年的冰输出事件是模拟中最大的，大约是平均值的两倍，相当于1600 km 3的过量淡水。格陵兰海的模拟上层水柱在1968年秋季的盐度最低，随后是非常低的冬季盐度。模拟结果表明，除了向格陵兰海输出高于平均水平的冰外，还有淡水输出，以支持高于平均水平的冰盖。三个低盐度异常，这是由冰生产/融化的变化，退出通过弗拉姆海峡在1963-1965年，1966年和1967-1969年，后两个事件与净淡水输出约900立方公里。格陵兰海2500 km 3的模拟淡水输入总量与GSA通过拉布拉多海时约2200 km 3的估计淡水过剩总量相比很好（Dickson等人，1988年）。考虑到模型中的不确定性，冰输出可能占淡水过剩的更大部分。然而，主要的结论是，这些模型结果表明，大南半球的起源是在北极，如Aagaard和Carmack（1989年）所建议的，并支持北极可能在气候变化中发挥积极作用的观点。
A fully prognostic Arctic ice-ocean model is used to study the interannual variability of the sea ice during the period 1955-1975 and to explain the large variability of the ice extent in the Greenland and Iceland seas during the late 1960's. In particular, the model is used to test the conjecture of Aagaard and Carmack (1989) that the Great Salinity Anomaly (GSA) was a consequence of the anomalously large ice export in 1968. The objective here is to explore the high-latitude ice-ocean circulation changes due to wind field changes. In the simulations the ice extent in the Greenland Sea increased during the 1960's, reaching a maximum in 1968, as observed, and maxima in ice extent were always preceded by large pulses of ice export through the Fram Strait. The ice export event of 1968 was the largest in the simulation, being about twice as large as the average and corresponding to 1600 km3 of excess fresh water. The simulated upper water column in the Greenland Sea has a salinity minimum in the fall of 1968, followed by very low winter salinities. The simulations suggest that, besides the above average ice export to the Greenland Sea, there was also fresh water export to support the larger than average ice cover. Three low-salinity anomalies, which are created by the variability in ice production/melt, exited through the Fram Strait in 1963-1965, 1966, and 1967-1969, the later two events being associated with a net freshwater export of about 900 km3. The total simulated freshwater input of 2500 km3 to the Greenland Sea compares well with the estimated total freshwater excess of the GSA of about 2200 km3 as it passed through the Labrador Sea (Dickson et al., 1988). Considering the uncertainties in the model, it is possible that the ice export could account for even larger portion of the freshwater excess. However, the main conclusion is that these model results show the origin of the GSA to be in the Arctic, as suggested by Aagaard and Carmack (1989) and support the view that the Arctic may play an active role in climate change.