Abstract
The interaction between an ocean eddy and incoming swell is investigated numerically producing characteristic refraction patterns of wave number and energy. The velocity distribution in the model eddy follows observations off Pt. Conception that are discussed in Sheres and Kenyon in this issue. The energy refraction patterns exhibit focus regions (caustics) where wave energy is concentrated; adjacent regions have a reduced wave energy concentration. Due to the eddy-induced refraction of incoming Pacific swell frequently observed in the area, approximately 20 km of coastline near Pt. Conception and about 5 km of coastline south of Morro Bay (California) would have relatively high waves. The Santa Maria Basin in between, as well as part of the entrance to the Santa Barbara Channel, would have relatively low waves. These gradients of wave energy depend on the velocity distribution of the eddy and the group velocity of the waves. Change in both the velocities while maintaining their ratio constant produces the same refraction patterns in the limited number of cases that were tested. During the 30 days residency of the eddy off Pt. Conception, the gradients of wave energy were likely to be significant. The potential effect of such gradients on the momentum exchange between wind and water (wind stress) and between waves and surface flow are discussed briefly.