The circulation and fluxes from the Arctic into the North Atlantic Ocean 1979-2002 model results

Abstract

The recent decreasing trend of sea ice cover in the Arctic region and its projected future reduction has direct implications for the global thermohaline circulation and the U.S. Navy. This thesis provides a qualitative and quantitative analysis of the freshwater export from the Arctic Ocean through the Canadian Arctic Archipelago (CAA) and the Fram Strait into the deep-water formation region of the Labrador Sea, using model data from 1979 to 2002. The results of this thesis directly aid the Navy in preparing personnel, ships, and weapons systems to operate efficiently in a possible ice-free Arctic. A coupled ice-ocean model of the pan-Arctic region at a 1/12-degree and 45-level grid resolution was used to produce data over a 24-year time period. The 24-year averaged annual velocity, temperature, and salinity profiles were compared for each of the analyzed stations. Additionally, 24-year mean monthly volume and freshwater flux time series plots and annual cycle plots were also produced to analyze the region's interannual variability from 1979 to 2002. The results show that the Canadian Arctic Archipelago is the major contributor of freshwater to the Labrador Sea. The CAA is a direct pathway for increased freshwater export from the Arctic into the sub-arctic seas where North Atlantic Deep Water(NADW)forms. The increased freshwater flux through the CAA, found in this study, supports the earlier reports on the freshening of NADW and a possibility of reduction in the meridional overturning rate in the North Atlantic. An increase in freshwater export from the Arctic is a good indicator of increasing sea ice reduction. The predicted opening of the Arctic to commercial and military vessels poses a direct threat to U.S. economical and strategic interests in the Arctic region. This thesis supports the U.S. Navy's ability to operate in a possibly ice-free Arctic.