New perspectives on Arctic Sea Ice Variability in the 20th Century

该项目将进一步加深我们对20世纪北极海冰及其与大气和海洋相互作用的了解。科学认识北极海冰的可变性受到卫星持续监测的时间相对较短(从1979年至今)以及20世纪上半叶未完成的海冰和大气观测的限制。该项目将对20世纪北极海冰和海面温度进行新的、实际的重建，并用它来研究20世纪初北极海冰变暖(ETCW)，这是1915-1940年间北极显著变暖的一个特别有趣的时期。ETCW是一个特别有趣的时期，因为众所周知，在1915-1940年间，北极显著变暖，但在此期间重建的海冰范围并没有显示出现实的相应海冰损失，因为海冰数据不佳。此外，广泛使用的20世纪再分析也未能捕捉到北极的ETCW，很可能是因为使用了这些海冰重建作为边界条件。因此，要研究ETCW和卫星之前的20世纪北极气候变异性，必须寻找其他工具。该项目将首先使用微动环流完全耦合地球系统模拟模拟和集合数据同化相结合的方法来创建20世纪北极海冰-海洋系统的物理一致性重建。其次，由于ETCW被认为是过去1000年来北极气候变化年代际变化最大的事件之一，其机制尚不清楚，该项目将通过以下研究问题来调查推动ETCW的机制：大西洋和太平洋在迫使ETCW中扮演了什么角色？海冰减少在推动ETCW中扮演了什么角色？新的北冰洋海冰-海洋系统重建将通过北极数据中心提供给研究界。该项目将支持一名早期职业研究人员和一名研究生。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project will further our understanding of Arctic sea ice in the 20th century and how it interacted with the atmosphere and ocean. Scientific understanding Arctic sea-ice variability is limited by the relatively short period of continuous monitoring by satellites (which covers 1979 to present) and incomplete sea ice and atmospheric observations for the first half of the 20th century. This project will produce a new, physically realistic reconstruction of Arctic sea ice and sea surface temperatures during the 20th century and use it to study Arctic sea ice during the Early 20th century Warming (ETCW), a particularly interesting period between 1915-1940 when the Arctic warmed significantly. The ETCW is a particularly interesting period, as it is well established that during 1915-1940 the Arctic warmed significantly, but reconstructions of sea-ice extent during that time do not show a realistic corresponding sea ice loss due to poor sea ice data availability. In addition, widely used 20th century reanalysis also fail to capture the ETCW in the Arctic, most likely due to the use of these sea ice reconstructions as boundary conditions. Thus, to study the ETCW and pre-satellite 20th century Arctic climate variability, one must look to other tools. This project will first create a physically consistent reconstruction of the 20th century Arctic sea ice-ocean system using a combination of nudged-circulation fully coupled earth system modeling simulations and ensemble data assimilation. Second, as the ETCW is identified as one of the largest episodes of multi-decadal Arctic climate variability in the last millennium and its mechanisms are still poorly understood, the project will investigate the mechanisms that drove the ETCW through the following research questions: what are the roles of the Atlantic and Pacific in forcing the ETCW?, and what is the role of sea ice loss in driving the ETCW? The new Arctic sea ice-ocean system reconstruction will be made available to the research community through the Arctic Data Center. The project will support an early career researcher and a graduate student.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.