Numerical Investigation of the Impacts of Offshore Wind Farms on Coastal Upwelling

Coastal upwelling is a persistent phenomenon along the U.S. West Coast due to predominantly northerly winds, and is magnified during the summer season. The wind-induced shear stress on the ocean surface combines with the Coriolis effect to drive surface water offshore, resulting in the upward transport of water from deeper within the ocean, a process known as coastal upwelling. Upwelling is particularly important to fisheries, due to the deeper water being both colder and richer in limiting nutrients. With future offshore wind power development planned for the U.S. West Coast, it is essential to investigate the potential impacts of wind farms on upwelling dynamics. In the Observationally Driven Resource Assessment with Coupled Models (ORACLE) project, we examine coastal upwelling characteristics along the U.S. West Coast using the Coupled-Ocean-Atmosphere-Wave-Sediment-Transport (COAWST) mesoscale model. We conduct month-long simulations that dynamically couple the atmosphere, waves, and ocean to understand the relationships between atmospheric flows and resulting upwelling dynamics. To assess the potential impacts of wind power generation on coastal upwelling within the region, we apply a tunable atmospheric drag model to represent various buildout scenarios of offshore wind generation within the Morro Bay lease area off the coast of central California. We analyze the resulting spatial and temporal changes in coastal upwelling both in terms of vertical velocities, and sea-surface temperature.

* This research was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Wind Energy Technologies Office. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-868574.