The California Current system in the Southern California Bight and the Santa Barbara channel

Recent observations in the Santa Barbara Channel and over the California Cooperative Oceanic Fisheries Investigations (CalCOFI) southern California grid are used to examine seasonal circulation patterns in and near the Southern California Eight, defined as the region east of the Santa Rosa Ridge and including the Santa Barbara Channel. Poleward flow relative to 500 m is found throughout the bight, in all seasons except for spring and all subregions except the western part of the Santa Barbara Channel. In spring there is equatorward flow throughout the bight at all depths to 500 m, though it tends to be surface or midcolumn intensified. Equatorward flow offshore of the bight, present in all seasons, narrows and accelerates into a jet-like feature and simultaneously moves close to the Santa Rosa Ridge in summer. Current meter data from the eastern entrance to the Santa Barbara Channel are consistent with the seasonal results from the CalCOFI data and further show an upward propagation of phase at annual period, with a phase speed of 1 to 2 m d(-1). Comparison with the CalCOFI ship winds suggests that poleward flow in the bight may be the result of positive wind stress curl, through a Sverdrup balance, though the observed transport is only about 75% of that expected from the curl amplitude. Equatorward flow in the bight may be the result of coastal upwelling, though the transport is larger than expected from the relatively weak winds in the bight, and the offshore extent of the equatorward flow is about 10 Rossby radii, farther than might be expected for linearized coastal upwelling. Equatorward flow outside the bight cannot be explained as a Sverdrup flow because the wind stress curl is positive throughout mast of the region. Upward propagation of phase and downward propagation of energy may be indicative of forcing by remote wind equatorward of the bight. Given the complexity of possible forcing mechanisms for circulation in and near the bight, a model that includes effects of remote wind forcing, Ekman pumping, and topography is needed to explain the observations in a satisfactory way.