HydroProfiler Portrait of a Monterey Bay Water Mass
The following plots show data collected with HydroProfiler on one cast in Monterey Bay, October 22, 2003 (cast 3). These data were collected over the deep Monterey Canyon.
The HydroScat-2 plot gives a good overview of the water structure; chlorophyll concentrations are high near the surface, tapering down to zero at about 50 meters depth. Scattering is also high in the surface layer, tracking the decrease in chlorophyll at increasing depth. However the scattering increases to a second peak at 130 meters. This peak is equal in magnitude to that near the surface, but note the differences: a greater separation between the red and blue backscattering traces, and no fluorescence. Thus the character of the particles in these two layers is distinctly different.
These plots show both the down- and up-cast. Note that there is another peak in scattering at about 105 meters, which appears only on the downcast. One might be tempted to attribute this to a momentary contamination problem on the HydroScat, except that it appears identically on all the other scattering and attenuation instruments (except the AC9). Its absence from the AC9 attenuation profile is probably due to the "smearing" effect of the pumped sample path of that instrument. Note that the 105-meter feature does not appear in the absorption measurements either by the a-Beta or AC9, suggesting it is due to mineral particles which typically have high scattering but low absorption.