A central California coastal ocean modeling study: 2. Adjoint sensitivities to local and remote forcing mechanisms

The sensitivity of particular features within the California Current System to remote and local forcing is numerically investigated using the adjoint model version of the Regional Ocean Modeling System. We define three integral measures of nearshore surface temperature, cross‐shore transport, and sea surface height as metrics that characterize important aspects of the coastal circulation. We determine the metrics' relative sensitivity to different components of the surface external forcing and model initial condition fields. Calculations are performed for 14‐d intervals over the 5‐year period from 2000 to 2004. Sensitivities are ranked in terms of their relative importance in the annual average, and their seasonal cycle is examined. Contributions from different portions of the domain are identified to determine the importance of local versus remote forcing. Local forcing, particularly wind stress and, at times, heat flux, are the dominant forcing contributors to temperature and transport sensitivities, although model initial conditions can contribute quantitatively on the same order as surface fluxes. The sea surface height metric reveals important nonlocal effects, particularly along the open boundary of this regional simulation.