Evolving Ice-Ocean Dynamics of the Western Arctic

Abstract

This dissertation examines the western Arctic Ocean and how its freshwater content and dynamics have evolved, particularly in the Beaufort Gyre circulation system north of Alaska. The recent growth of the Beaufort Sea Seasonal Ice Zone and its large freshwater content relative to the rest of the Arctic Ocean make it an ideal laboratory to understand the transformation of the air-ice-ocean physical system under a changing climate. We consider this system in part through the lens of its freshwater, bringing together in-situ and satellite observations and models to describe changes in mixed-layer salinity, ocean velocity, and surface stress. The first part of this manuscript looks at the effect of large-scale sea ice retreat on local ocean mixed-layer freshwater content, and the second part examines changes in ocean and ice circulation speeds—and with them, resulting surface stresses—over time. These changes affect ocean freshwater content and gyre equilibration, both of which are observed to have stabilized in the last decade after a period of spin-up. The third part of this dissertation examines how ice-ocean stress coefficients behave at daily to monthly timescales, and how they too may have changed in recent decades. Together, this work provides a three-dimensional, updated description of how the Beaufort Sea surface physical system operates and transports freshwater, especially under recently diminished ice cover.