The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf
The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf
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DOI：
10.5194/tc-14-2173-2020
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发表时间：
2020-07-06
期刊：
影响因子：
5.2
通讯作者：
Watkins, Daniel
中科院分区：
文献类型：
--
作者：
Krumpen, Thomas;Birrien, Florent;Watkins, Daniel
2019年9月，极地号研究破冰船开始了迄今为止最大的多学科北极考察，即MOSAiC（北极气候研究多学科漂流观测站）漂移实验。在浮冰上停泊了整整一年，因此包括冬季，探险队宣布的目标是更好地了解和量化影响海冰质量和能量预算的大气-冰-海洋系统内的相关过程，最终导致大大改善气候模型。卫星观测、大气再分析数据和附近气象站的读数表明，冬季末的高冰输出和异常高的气温相互作用导致了自可靠的仪器记录开始以来最长的无冰夏季。我们使用拉格朗日跟踪工具和热力学海冰模型表明，携带中央天文台（CO）的MOSAiC浮冰于2018年12月初在新西伯利亚群岛北部的冰间湖事件中形成。结果进一步表明，CO附近（< 40 km距离）的海冰比周围的冰更年轻，薄36%，这对冰动力学以及海洋和大气之间的动量和热量传递有潜在的影响。2019年秋季对各种参考浮冰进行的海冰调查证实了冰厚度的这种梯度，在CO周围的冰芯（所谓的脏海冰）中发现的沉积物证实了在生长的早期阶段与浅水沃茨的接触，与跟踪分析一致。由于西伯利亚大陆架上的冰在第一个夏天存活下来的越来越少（Krumpen等人，MOSAiC实验为研究海冰作为气体、常量营养素、铁、有机物、沉积物和污染物从大陆架地区向北冰洋中部及更远地区的运输介质的作用提供了独特的机会。与过去26年的数据相比，2019年9月底遇到的海冰已经可以被归类为异常薄，进一步预测季节性无冰海洋的变化可能会切断冰漂流物的远程运输未来的跨极漂流。海冰远距离迁移的减少将对北冰洋中部生物地球化学物质的重新分布产生重大影响，从而影响到北冰洋与气候有关的微量气体的平衡、初级生产和生物多样性。
In September 2019, the research icebreaker Polarstern started the largest multidisciplinary Arctic expedition to date, the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) drift experiment. Being moored to an ice floe for a whole year, thus including the winter season, the declared goal of the expedition is to better understand and quantify relevant processes within the atmosphere-ice-ocean system that impact the sea ice mass and energy budget, ultimately leading to much improved climate models. Satellite observations, atmospheric reanalysis data, and readings from a nearby meteorological station indicate that the interplay of high ice export in late winter and exceptionally high air temperatures resulted in the longest ice-free summer period since reliable instrumental records began. We show, using a Lagrangian tracking tool and a thermodynamic sea ice model, that the MOSAiC floe carrying the Central Observatory (CO) formed in a polynya event north of the New Siberian Islands at the beginning of December 2018. The results further indicate that sea ice in the vicinity of the CO ( < 40 km distance) was younger and 36 % thinner than the surrounding ice with potential consequences for ice dynamics and momentum and heat transfer between ocean and atmosphere. Sea ice surveys carried out on various reference floes in autumn 2019 verify this gradient in ice thickness, and sediments discovered in ice cores (so-called dirty sea ice) around the CO confirm contact with shallow waters in an early phase of growth, consistent with the tracking analysis. Since less and less ice from the Siberian shelves survives its first summer (Krumpen et al., 2019), the MOSAiC experiment provides the unique opportunity to study the role of sea ice as a transport medium for gases, macronutrients, iron, organic matter, sediments and pollutants from shelf areas to the central Arctic Ocean and beyond. Compared to data for the past 26 years, the sea ice encountered at the end of September 2019 can already be classified as exceptionally thin, and further predicted changes towards a seasonally ice-free ocean will likely cut off the long-range transport of ice-rafted materials by the Transpolar Drift in the future. A reduced long-range transport of sea ice would have strong implications for the redistribution of biogeochemical matter in the central Arctic Ocean, with consequences for the balance of climate-relevant trace gases, primary production and biodiversity in the Arctic Ocean.