C. N. K. Mooers

A summary of the OPTOMA program's mesoscale ocean prediction studies in the California current system

Abstract The OPTOMA program sampled the California Current System mainly on the continental rise off Northern California from March 1982 to November 1986. Maps of surface dynamic height from OPTOMA surveys during summer show intense offshore jets and associated eddies in the coastal transition zone. The current meanders during summer tend to be sharper than those during winter so that eddies often have smaller horizontal scale. The mean, the standard deviation and the range of the dynamic height, and maximum surface current speeds are larger in summer than in winter. In both seasons, the horizontal structure at 200 db, relative to 450 db, is weak; current filaments are less prominent at this depth than at the surface and the regions of strongest flow are associated with eddies. An array of three moorings, separated by about 100 km, is influenced by small-scale eddies which may account for the lack of large-scale coherence between velocity or temperature variations at the three moorings. Some features appear to propagate offshore, and the temperature at the offshore mooring clearly shows the influence of onshore/offshore advection. From dynamical model hindcast experiments, as well as from dynamic height maps, both local instability processes and wind stress curl forcing are important to the evolution of mesoscale features off Northern California.