Circulation in the Santa Maria Basin and Santa Barbara Channel

Moored observations and numerical model results are used to describe the 1998 circulation in Santa Maria Basin (SMB) and Santa Barbara Channel (SBC), located to the northwest and southeast respectively of a bend in the southern California coastline.; Winds in the area are equatorward throughout the year, strongest at SBC's western mouth and weak inside SBC. In spring, the near-surface currents are equatorward everywhere except along SBC's northern shelf, where it is poleward. In summer this poleward flow grows stronger, and flow at SBC's eastern mouth also turns poleward. SMB currents are generally equatorward throughout the year, with short periods of poleward flow in summer. SVD analysis of currents and winds suggests that large-scale changes in winds and currents are related, as are poleward flow along SBC's northern shelf and wind stress shear along SBC.; A three-dimensional numerical ocean circulation model is used to simulate the 1998 flow. It is forced by daily wind stress maps derived from observed winds. The model is run with and without assimilation of observed temperatures; the latter tends to result in colder water temperatures, which implies that surface heat flux (which is not included in the model, but whose effects are incorporated into the model by temperature assimilation) is important. The surface heat flux estimated from the model is most similar to observation-derived values in summer and least similar in winter. They are more similar in SMB than in SBC, which suggests that model transport is more realistic in the former.; EOF analysis of the Coriolis and pressure gradient terms for modeled near-surface currents suggests that wind stress drives currents in SMB (and SBC in spring), and an alongshore pressure gradient drives the poleward flow along SBC's northern shelf. A veering of winds in early summer may cause both the end of SBC's equatorward flow and development of its poleward flow (by giving rise to the alongshore pressure gradient).; Modeled and observed currents are similar in direction, but both the mean and variance tend to be smaller for modeled flow. SVD analysis shows that modeled and observed flows have similar modes of variability.