Date

Spring 2026

Document Type

Master's Thesis (Open Access)

Degree Name

Master of Science (M.S.)

Department

Moss Landing Marine Laboratories

Abstract

Coastal submarine canyons are dynamic environments where internal waves, wind forcing, and complex bathymetry interact to regulate physical and biogeochemical variability. This study investigates how intra- and interannual variability in internal waves and upwelling-favorable winds influence cold-water mass intrusions and associated biogeochemical responses at the head of the Monterey Bay Submarine Canyon. Using a 2010--2021 time series of nearshore physical and chemical observations from the Moss Landing Marine Laboratories intake system, combined with local and offshore wind measurements, this work examines variability across seasonal to interannual timescales. Results show that semidiurnal M2 internal tides are the primary drivers of cold, nutrient-rich, oxygen-poor water intrusions into the nearshore. These intrusions are strongly modulated by seasonal stratification, with enhanced internal wave energy and nonlinear behavior during spring and summer, and reduced activity during winter. Diurnal sea breezes further modulate nearshore variability by enhancing local upwelling and contributing to high-frequency temperature fluctuations, particularly during the upwelling season. However, internal wave dynamics remain largely independent of local wind forcing, indicating distinct but interacting physical mechanisms. Biogeochemical variables, including dissolved oxygen, nitrate, pH, and fluorescence, are tightly coupled to these physical drivers, reflecting repeated delivery of subsurface water to the canyon head. Interannual variability, including reduced physical-biogeochemical coherence in 2019, highlights sensitivity to broader climate conditions. Overall, this study demonstrates that canyon bathymetry, internal wave dynamics, and wind forcing jointly regulate the timing and magnitude of nearshore physical and biogeochemical variability, with implications for coastal productivity and ecosystem resilience.

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