Evaluation of Real-Time High-Resolution Forecasts for Monterey Bay

Real-time high-resolution forecasts over the Central California Coast and Monterey Bay regions have been performed routinely for the last several years using the atmospheric portion of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) (available online at http://www.nrlmry.navy.mil/coamps-web/web/home) and are widely used in the meteorology and oceanography communities for a variety of applications. Forecasts of 48 hours are provided twice daily over four nested domains with the most inner domain at a 3-km horizontal resolution. In this study, monthly surface temperature and wind bias and RMS are computed using a coastal mesoscale network of buoy observations and surface stations to evaluate the model performance with a particular focus on the coastal low-level jet and flow relaxation situtations, which have a large-influence on the local upwelling response. An evaluation of different nested domains highlights the impact of the model resolution on the forecast of the low-level jet and attendant features including expansion fans and hydraulic jump structures. Statistical verification of the real-time model forecasts suggests that the finest resolution mesh is more skillful in replicating the intricate flows over the Monterey Bay region including the strong gradients associated with the juxtaposition of the offshore low-level jet and wake in the lee of the coastal terrain, which are crucial for driving coastal upwelling.