Date of Award

Spring 2020

Document Type

Open Access Thesis

Department

Marine Science

First Advisor

Subrahmanyam Bulusu

Abstract

Salinity and freshwater fluxes are important tools for monitoring the amount of freshwater entering and exiting the Arctic Ocean. Satellite-derived salinity provides a way to study surface advective freshwater fluxes; however, sea ice contamination, among others, remains an obstacle in the accuracy and reliability of these measurements. In this study, salinity and surface freshwater fluxes are calculated using NASA’s Soil Moisture Active Passive (SMAP) and the ESA’s Soil Moisture Ocean Salinity (SMOS), Argo, and the European Centre for Medium-Range Weather Forecast’s Ocean Reanalysis version 4 (ORAS4). ORAS4 compares well to Argo in the subarctic seas and is used for comparison to the satellites in the Bering Strait and Barents Sea Opening (BSO). There is agreement between satellites and ORAS4 on average and variability of freshwater fluxes in the Bering Strait, demonstrating the potential satellites have to study these fluxes in lower latitude subarctic regions with high freshwater variability. In the BSO, however, the satellites were not able to capture similar fluxes as ORAS4, indicating the need to improve satellitederived salinity in polar regions.

This finding is increasingly important as the Arctic changes and more accurate, widespread data are needed. Satellites and models are

used to examine decadal changes in the Arctic Ocean and subarctic seas. Salinity has undergone one of the most significant changes, as there is a juxtaposition of trends, with the Canada Basin freshening, and many other seas undergoing salinification. This is caused by decreasing sea ice, and a shift toward an anticyclonic atmospheric circulation regime over the Arctic, which alters riverine flow,

freshwater output, and Beaufort Gyre strength. Increasing ocean temperatures across the Arctic Ocean and most significantly, the subarctic Atlantic region, are also found. This likely contributed to thermal expansion which, in addition to ice sheet loss, has caused increasing sea level anomalies across the Arctic and subarctic regions. The warming and salinification in the subarctic Atlantic and Barents Sea may be due to an increased proportion of Atlantic waters in the region, owing to the shift to a more anticyclonic circulation regime in the late 1990s.

Rights

© 2020, Rachel Elizabeth Nichols

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