Henry Vanderploeg
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 mgL-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.