Distribution of suspended particulate matter off the California coast from San Francisco Bay to Cape San Martin

Abstract

The distribution of suspended particulate matter in the 1.4 to 27. 9y range based on data gathered during four cruises off the California coast from San Francisco to Cape San Martin is presented by means of iso-metric drawings as well as more conventional graphs . It was observed that pycnoclines set up particle "traps." In areas where a deep mixed layer existed particle concentrations were randomly distributed in the layer. Counts of larger sized particles decreased with depth; those for smaller particles appeared to remain about constant throughout the water column. Particle sizes and distributions reflected bottom topography and water depth. Shallow water stations exhibited higher particle concentrations, while stations over Monterey Canyon showed depressed counts over the entire size range. In localized upwelling areas higher concentrations around the areas' peripheries than in their centers were found. Data -C/3 -C were assumed to follow a distribution of the form M. =K(l-2 ) D • where M. = count in Coulter counter channel i (i = 0,1, ...,13), -i/3 K and C are constants, and D> = 27.9 x 2 is the diameter in u of channel i. C values generally occurred in the 2.4 to 3.1 range, but significant deviations were noted during upwelling. 3 K values often fell in the 50 to 300 x 10 particles/ml range, but extremely high values were noted for the Davidson Current period. Phytoplankton blooms appeared to be responsible for "knees" or "peaks" in many of the size distributions.