The Southern California Bight (SCB), an eastern boundary upwelling system, is impacted by global warming, acidification and deoxygetation, and receives anthropogenic nutrients from a coastal population of 20 million people.
We describe the configuration, forcing, and validation of a realistic, submesoscale resolving ocean model as a tool to investigate coastal eutrophication. This modeling system represents an important achievement because it strikes a balance of capturing the forcing by U.S. Pacific Coast-wide phenomena, while representing the bathymetric features and submesoscale circulation that affect the vertical and horizontal transport of nutrients from natural and human sources.
Moreover, the model allows to run simulations at timescales that approach the interannual frequencies of ocean variability, making the grand challenge of disentangling natural variability, climate change, and local anthropogenic forcing a tractable task in the near-term. The model simulation is evaluated against a broad suite of observational data throughout the SCB, showing realistic depiction of mean state and its variability with remote sensing and in situ physical-biogeochemical measurements of state variables and biogeochemical rates. The simulation reproduces the main structure of the seasonal upwelling front, the mean current patterns, the dispersion of plumes, as well as their seasonal variability. It reproduces the mean distributions of key biogeochemical and ecosystem properties. Biogeochemical rates reproduced by the model, such as primary productivity and nitrification, are also consistent with measured rates. Results of this validation exercise demonstrate the utility of fine-scale resolution modeling in support of management decisions on local anthropogenic nutrient discharges to coastal zones.