"Upwelling" and "cyclonic" regimes of the near-surface circulation in the Santa Barbara Channel

The observed near-surface circulation in the Santa Barbara Channel indicate s in particular two patterns: a dominant cyclonic circulation mode and a le ss frequent upwelling flow mode. To explain the dynamics that may govern th ese two flow regimes, momentum balance from a hindcast model of currents in the channel, forced by observed hourly winds and hydrographic data, was ca lculated. The along-channel balance was found to be between wind, which was eastward (i.e., equatorward), sea level tilt, which was westward (i.e., po leward), and Coriolis, which was westward if the wind was (1) intense west and east of the channel and was eastward if the wind was (2) weaker in the east. Wind condition 1 produced southward cross-channel flow in the midchan nel, connected by eastward currents upstream (downstream) along the norther n (southern) coast of the channel, while wind condition 2 produced northwar d cross-channel flow connected by cyclonic recirculation in the west and we stward inflow in the east. It is suggested that the former corresponds to t he dynamical balance that may occur in the upwelling flow mode, while the l atter corresponds to the cyclonic circulation mode.