An Investigation of the Catalina Eddy

Abstract

Abstract The Catalina eddy event of 21 July 1992 is simulated using a mesoscale data assimilation system featuring an optimum interpolation analysis, incremental update, and second-order closure physics. The results are contrasted with other recent modeling studies of the Catalina eddy. Genesis of the eddy occurs when changes on the synoptic scale lead to an intensification of the east–west pressure gradient near the coast, resulting in enhanced northwesterly flow along the coast and over the mountains east of Point Conception. Lee troughing results in an alongshore pressure gradient at the coast with higher pressure to the south. Topographically trapped, ageostrophic southerly flow is then initiated. The combination of southerly flow along the coast with strong northwesterly flow to the west results in formation of a cyclonic eddy in the bight. The zone of southerly flow is characterized by a deep, cool, cloud-topped boundary layer that can considerably alter coastal weather and impact activities involve...