Characteristics of an intense ocean frontal system in the upwell regime west of Cape Town

During a week in February, 1968, a series of detailed BT transects of the frontal zone and out to 100 miles seawards demonstrated the location of the surface front between zones of inshore and offshore divergence, and between zones of surface mixing to seaward and bottom mixing beneath and inshore of the front. Marked changes in surface temperature patterns within hours of wind vector reversals emphasize the sensitivity of the wind stress/surface front intensity relationship but, due to more random variability, corresponding changes are not detectable at depth. The action of mixing cells within the front is shown to combine with overturning events to produce transient sub-thermoclinal sheets of relatively homogenous water. The cells also provide a postulated trans-frontal advection mechanism for small quanta.