UC Irvine

Previous studies indicate that cold filaments off northern California have sharp southern (s-type) and diffuse northern (d-type) thermal boundaries. In this study, 44 AVHRR satellite images taken from three coastal regions in the California Current System (northern, central, and Baja California) over a period of 10 years were used to examine the regional variation in surface frontal structure associated with cold filaments. The images were specifically chose from months where past mean wind conditions indicated upwelling occurred because cold filaments appear to be more abundant during the upwelling season. The images also were chosen to provide independent realizations of filament structure. Distributions of average gradient magnitude as a function of gradient angle were used to provide a more compact representation of the frontal information contained in each image. An analysis of these distributions shows that the sharp / diffuse boundary structure associated with cold filaments observed in shipboard data dominates the total surface frontal structure found in satellite data for two of the three regions studied. The recurrent, ubiquitous patterns found in the satellite-determined frontal structure are discussed in terms of their potential effects on acoustic propagation and regional implications on ecological community structure in the California Current System. © 1993.