Arctic Ocean Warming Contributes to Reduced Polar Ice Cap
Arctic Ocean Warming Contributes to Reduced Polar Ice Cap
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DOI：
10.1175/2010jpo4339.1
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发表时间：
2010-12-01
影响因子：
3.5
通讯作者：
Toolen, John
中科院分区：
文献类型：
--
作者：
Polyakov, Igor V.;Timokhov, Leonid A.;Toolen, John
对现代和历史观测的分析表明，近几十年来北冰洋中深度（150-900米）大西洋水（AW）的温度有所上升。全球变暖在时间上是不平衡的；在20世纪90年代中期观测到一个类似于1摄氏度的局部最大值，随后出现了其间的一个最小值和一次额外变暖，2007年达到顶峰，气温比20世纪90年代高0.24摄氏度。相对于1999年之前所有数据的气候学，2007年在欧亚和马卡罗夫盆地观测到的最极端的温度异常高达1摄氏度甚至更高。阿瓦西变暖与北冰洋中部阿瓦西上边界的大量（高达75-90米）浅滩化和欧亚盆地上层海洋分层的减弱有关。综上所述，这些观测结果表明，欧亚盆地的变化促进了更多的AW热量向上转移到海洋表层。现有的有限观测和ID海柱模式的结果支持这一通过欧亚盆地盐斜向上传播的AW热的推测。三维冰-海洋耦合模式的实验反过来表明，在类似50年后，由于1D模式显示的海洋热通量增加0.5 W m(-2)，冰厚损失了28-35 cm。这一减薄量与根据快速冰厚下降观测估计的局地大气热力强迫造成的29厘米冰厚损失相当。这意味着，近年来观测到的极端冰损失中，AW变暖帮助极地冰帽形成了先决条件。
Analysis of modern and historical observations demonstrates that the temperature of the intermediate-depth (150-900 m) Atlantic water (AW) of the Arctic Ocean has increased in recent decades. The AW warming has been uneven in time; a local similar to 1 degrees C maximum was observed in the mid-1990s, followed by an intervening minimum and an additional warming that culminated in 2007 with temperatures higher than in the 1990s by 0.24 degrees C. Relative to climatology from all data prior to 11999, the most extreme 2007 temperature anomalies of up to 1 degrees C and higher were observed in the Eurasian and Makarov Basins. The AW warming was associated with a substantial (up to 75-90 m) shoaling of the upper AW boundary in the central Arctic Ocean and weakening of the Eurasian Basin upper-ocean stratification. Taken together, these observations suggest that the changes in the Eurasian Basin facilitated greater upward transfer of AW heat to the ocean surface layer. Available limited observations and results from a ID ocean column model support this surmised upward spread of AW heat through the Eurasian Basin halocline. Experiments with a 3D coupled ice-ocean model in turn suggest a loss of 28-35 cm of ice thickness after similar to 50 yr in response to the 0.5 W m(-2) increase in AW ocean heat flux suggested by the 1D model. This amount of thinning is comparable to the 29 cm of ice thickness loss due to local atmospheric thermodynamic forcing estimated from observations of fast-ice thickness decline. The implication is that AW warming helped precondition the polar ice cap for the extreme ice loss observed in recent years.