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

University Of Washington, Seattle WA

Investigators

Abstract

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.