An eddy, coastal jets and incoming swell all interacting near Pt Conception, California

Abstract

Abstract Observations of ocean features and their interaction near Pt Conception, California, are reported for a two-month period during the early spring of 1983 at the time of the El Nino. The development of a body of warm water into a clockwise rotating eddy is described and the observed increase in the spatial scale of the eddy is found to compare favourably with the value calculated rrom a model of geostrophic adjustment. The subsequent interaction of the warm core eddy with a cold coastal jet directed offshore is discussed in relation to the approximate one-month lifetime observed for the eddy. The interaction of the eddy with incoming swell, and the resulting gradients in wave energy and wind stress are discussed in an accompanying paper in this issue (Sheres and Kenyon 1989). The measurements in this report are based mainly on NOAA-7 infrared images, but in situ current and wind data from moorings and temperature and salinity data from a California Cooperative Fisheries Investigation (CALCOFI) cruise are used as well. Water velocities up to 55cm/s (averaged over 12-24 hours) were calculated from tracing temperature features in successive infrared images; they compare well with CALCOFI and moored near-surface current data, when available.