SEASONALITY OF CHLOROPHYLL CONCENTRATIONS IN THE CALIFORNIA CURRENT: A COMPARISON OF TWO METHODS

We have compared estimates of seasonal variations in chlorophyll concentrations in the California Current as derived from a large series of in situ, water-column, measures and from the Coastal Zone Color Scanner-West Coast Time Series (WCTS) in both original and corrected forms. We find substantial differences between the two methods, satellite and in situ. The original WCTS showed winter to be the peak season for pigment concentration everywhere, but the in situ data did not. A previous study of the corrected WCTS data found “a strong seasonal cycle with a spring summer maximum,” but the in situ data contained no convincing evidence for a “strong” cycle when all ofthe data were examined. Some individual years (e.g., 1984) do have clear spring maxima, particularly very near shore, but most do not. There are extensive interannual variations. The overall relation between surface in situ (or 020 m) pigment concentrations and integrated, in situ water-column (0-150 m) concentrations is very uncertain in terms of mean concentrations per unit volume, spatial heterogeneity, and temporal change.