Spatial and temporal variability of phytoplankton pigment off northern California during Coastal Ocean Dynamics Experiment 1

Abstract

The distribution of phytoplankton pigment during the 1981 Coastal Ocean Dynamics Experiment (CODE) was examined using coastal zone color scanner (CZCS) imagery. Twenty‐five CZCS images were of sufficient quality to be used for further analysis. The distribution of the data was dependent on the patterns of wind forcing, with the data set biased toward regions and periods of strong equatorward winds. The weighted mean pigment image and the coefficient of variation image showed three clearly defined regions: a coastal region approximately 100 km wide, an offshore region of low pigment and low variability, and two filaments that extended several hundred kilometers offshore. Coastline topography and longshore variations in wind forcing are important in the coastal region. The offshore filaments appear to be related to the patterns of wind stress curl and perhaps explain the large‐scale patterns of Zooplankton biomass in the California Current. Analysis of the temporal variability delineated three nearshore areas: a northern region off Cape Mendocino a central region near the CODE Central line, and a southern area off San Francisco. The width of the coastal zone seemed to vary with a 5‐ to 6‐day cycle. During two equatorward wind events, the patterns of temporal variability were consistent with the patterns of wind forcing revealed by empirical orthogonal function decomposition.