Variability of the ocean surface color field in central California near-coastal waters as observed in a seasonal analysis of CZCS imagery

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Abstract
A time series of Coastal Zone Color Scanner images has been analyzed, on a seasonal basis, to gain a perspective on the ocean surface color field heteogeneity in central California near-coastal waters. Seasonal composite maps of the diffuse attenuation coefficient at 490 nm were derived, in the form of arithmetic means and corresponding variances, for the years 1981, 1982 and 1983. By identifying "open ocean," "transition" and "coastal" water types in the mean images, and comparing values and areal extension of each class in different periods and years, a distinct seasonality of the spatial characteristics of ocean color emerged. Analogous seasonal cycles are evident in the variance images. Both parameters present a more pronounced, extensive and convoluted surface structure in the spring-summer periods, followed by an intermediate stage in fall and much reduced variability in the winter periods. This seasonal trend is maintained regardless of the high degree of interannual variability most evident in the spring-summer cnditions. Possible interpretations of the imagery in terms of the oceanographic "climate" of the region are discussed, as reflecting the combined effects of coastal processes and offshore mososcale dynamics typical of the California Current System. A profound influence of the bathymetric relief on surface structure, even in deep ocean areas, is finally documented by the data set.