How Winds and Sea Level Differences Control Coastal Ocean Currents

Wind relaxations occurring at Point Conception, a major biogeographic boundary, lead to a reversal of the coastal ocean circulation pattern. These flows propagate poleward around Point Conception, running opposite of the prevailing wind, and are important for their role in larval delivery to tidal and intertidal habitats along the central Californian coast. The relationship between the characteristics of these flows and their structure will be examined. 4 Oceanographic moorings collected temperature and velocity profiles of the water column as well as pressure measurements along the 15 m ocean depth line. Bottom pressure time series indicated that a sea level differences developed between north and south of Point Conception when the winds were blowing. When they weaken, the water moves from the high region in the Santa Barbara Channel to the lower region north of Point Conception. Nearly simultaneous temperature increases across the water column indicate a vertical front associated with these flows. The flow can be partitioned into a nose region with alongshore and cross shore components of velocity and a tail region where the alongshore flow is farther offshore. The alongshore and cross shore scale of the nose region is roughly 10 km and 10-20 km respectively. Understanding the temporal and spatial scales of poleward flow events will improve our ability to understand the mechanisms of larval delivery across biogeographic boundaries.