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Stevens, Samuel William

University of British Columbia

Coastal oceans are disproportionately important compared to their limited size. Semi-enclosed coastal areas, in particular, are geomorphologically diverse regions that often support high primary productivity and can offer rich sheltered habitats for large marine communities. Due to their enclosed nature, these areas are uniquely vulnerable to the impacts of climate change and pollution as deep water masses can have long residence times, which can generate hypoxic conditions and cause an accumulation of long-lived contaminants, among other issues. Understanding the subsurface circulation of these areas is important to understanding and predicting the evolution of these conditions. However, the processes that drive circulation occur on time and space scales that span the entire coastal continuum, ranging from synoptic-scale processes at the ocean margin through to microscale processes in the interior basins. For this reason, semi-enclosed seas are often under-sampled relative to the multiple scales of variability that drive their circulation. Here, I present research on the subsurface circulation of two of North America's largest deep stratified marginal seas: the Salish Sea, with a particular focus on the Strait of Georgia; and the Gulf of St. Lawrence. These areas have diverse geographic features, yet share a number of oceanographic similarities, such as exhibiting rotationally-modified estuarine circulations. In these regions, I outline and quantify subsurface mixing dynamics, transit times, transit pathways, and advection speeds via observations, regional-scale model outputs, and simplified 1D models. One strong motivation for this research was to generate novel tools for oceanographers to study these regions and similar regions globally. I have approached this in a number of ways. For example, I make broad use of hydrographic data gathered via an extensive volunteer program in British Columbia, highlighting the utility and efficacy of citizen science as a scientific resource. Furthermore, over a three year period, I designed, developed, and deployed a new neutrally-buoyant float system, nicknamed "Swish floats", to provide low cost Langrangian measurements of subsurface dispersion. Finally, I spearheaded analyses in the first ever deliberate subsurface tracer release experiment in the Gulf of St. Lawrence.

Text

2024-03-04

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87517

Oceanography

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/