Henry Vanderploeg NOAA/GLERL 2205 Commonwealth Blvd Ann Arbor, MI 48105-2945 Phone: 734-741-2284 Fax: 734-741-2055 Email: Henry.Vanderploeg@noaa.gov Explanation of Columns in Data Set Time Running PSS Time (sec) PSS Depth Depth of PSS (m) Water Temp Water Temperature (deg C) Light Atten Relative Light Attenuance, (air ~ 110, SEE Note 1) TSM Derived TSM (mg/l), SEE Note 2 PAR Photosynthetically active radiation (E15 quantum/cm sq./sec.) Chl Conc Derived chlorophyll-a concentration (ug/l), SEE Note 3 Total Counts Total Zooplankton Counts (No./L) Bin1 Counts Zooplankton Counts in 1st bin size (No./L) Bin2 Counts Zooplankton Counts in 2nd bin size (No./L) Bin3 Counts Zooplankton Counts in 3rd bin size (No./L) Biomass Zooplankton Biomass (mg wet wt/L) Water Depth Approx water depth at location of PSS (m), based on NOAA 9 arc-sec bathymetric data set Dist from Shore Approx dist from shore (km), based on lambert conformal conic projection Note 1. During the plume event of 1998, we discovered that the OPC could not detect zooplankton at TSM concentrations > 20 mg·L-1 (Ruberg et al. 2001). To overcome this difficulty, we increased light intensity of the OPC diodes by a factor of 9.3 in 1999 and 2000. This decreased the range of LA values registered by the OPC by a factor of 9.3. To make all data comparable, we divided the 1998 LA values by 9.3. Note 2. TSM is derived from PSS-LA output. Regression developed by J. Liebig (GLERL) using observed TSM values and corresponding PSS-LA. For a detailed explanation of the TSM regression equations, see detailed methods. Note 3. Chl-a is derived from fluorometer output (volts). Regressions developed by J. Liebig (GLERL) using extracted chls and corresponding pss fluor. volts. For a detailed explanation of the CHL regression equations, see detailed methods. PSS underwater assembly includes the Focal Technologies Mini-Optical Plankton Counter (OPC), the Ocean Sciences OS-200 CTD with X-Y tilt sensor, and a Chelsea Aquatracka III fluorometer (logarithmic amplifiers, chlorophyll range: 0.1-100 ug/L) mounted on an Endeco/YSI Type 493 V-fin. The system also includes a differential GPS and depth sounder. The PSS is towed in a vertically undulating (tow-yowed) mode as the ship travels at about 2.5 m/s.