Surface waves in the Beaufort Sea

Thesis (Master's)--University of Washington, 2016-06

The rapidly changing Arctic sea ice cover affects surface wave growth across all scales. The effect of sea ice extent on wave growth is studied using in situ measurements of waves observed from freely-drifting buoys during the 2014 open water season. Wave measurements made in open water areas of the Beaufort Sea are interpreted using open water distances determined from satellite ice products and wind forcing time series measured in situ with the buoys. A significant portion of the wave observations are found to be limited by open water distance (fetch) when the wind duration was sufficient for wind and wave conditions to be considered stationary. The scaling of wave energy and frequency with open water distance demonstrates the indirect effects of ice cover on regional wave evolution. Waves measurements in partial ice cover in the marginal ice zone (MIZ) can be similarly categorized as distance-limited by an ‘effective fetch’, representing the distance between ice floes, calculated by applying the fit from the open water scaling. The process of local wave generation in ice appears to be a strong function of the ice concentration, wherein the ice cover severely reduces the effective fetch. The wave field in the Beaufort Sea is thus a function of the sea ice both locally, where wave growth primarily occurs in the open water between floes, and regionally, where the ice edge provides a more classic fetch limitation. Observations of waves in recent years may be indicative of an emerging trend in the Arctic Ocean, where we will observe increasing wave energy with decreasing sea ice extent.