NOAA - Great Lakes Environmental Research Laboratory

Plankton Survey System (PSS) Metadata

The Plankton Survey System (PSS) underwater assembly includes the Focal Technologies Mini-Optical Plankton Counter (OPC), the Ocean Sciences OS-200 CTD, a Chelsea Aquatracka III fluorometer (logarithmic amplifiers, chlorophyll range: 0.1-100 µg/L), a Seabird SBE 43 dissolved oxygen (DO) sensor, and a photosynthetically active radiation (PAR) sensor mounted on an Endeco/YSI Type 493 V-fin. The PAR sensor was a Biospherical QCP 200L (cosine) for the May 2005 cruises and a QSP-200L (3.8 PI) beginning in June 2005. To determine vertical structure of plankton and related physical variables along the ship's path, the PSS was towed in a vertically undulating (tow-yowed) mode as the ship traveled at about 2.5 m/s.

On deck, a laptop computer with OPC data acquisition software provided by Focal was used to collect data and monitor the PSS through the OPC deck unit. The software displays plankton counts and size, light attenuance, flow rate, depth and GPS information. The software also serves as the data acquisition system for all data including conductivity, temperature, pressure, fluorescence, DO, and PAR. Since the PSS was used in shallow water, very accurate depth and GPS location was required. This information was provided by the ship's WAAS enabled GPS and depth sounder, and latitude and longitude were sent to the PSS laptop for spatial registration of all PSS data. Depth and GPS information was also monitored on the ship's computer display located in the wet lab during PSS operation.

Chlorophyll a Regression Equation (J. Liebig):

Chlorophyll a (µg/L) was derived from the fluorometer output (volts) using regression equations developed by J. Liebig using extracted chlorophyll a and PSS fluorescence (converted to antilog volts) from IFYLE 2005 cruises in Lake Erie. Because the phytoplankton community changes seasonally, separate regressions were done for May-June 2005, July-August 2005, and September 2005 (transect cruise). The PSS fluorometer did not function during the September diel and October cruises.

May-June: chl(µg/L) = 0.0143 * 10^volts + 0.0024
July-August: chl(µg/L) = 0.0194 * 10^volts - 0.0154
September: chl(µg/L) = 0.0277 * 10^volts + 0.0201

Dissolved Oxygen Equation (S. Ruberg):

dissox1= ;output
tempa= ;absolute temp
soc_do=0.3611
tcor_do=0.0002
pcor_do=1.35e-4
voff_do=-0.4704
a_do=7.556803
b_do=-0.0003656848
;volts
do_volts=a_do+b_do*dissox1
;oxygen saturation
oxsat=exp(a1_do+a2_do*(100./tempa)+a3_do*alog(tempa/100.)+a4_do*(tempa/100.))
; do, mg/l
dissox=1.42903*soc_do*(do_volts+voff_do)*oxsat*exp(tcor_do*temp)*exp(pcor_do*depth_ctd/1.019716)

2005 DO Data Correction:

It was determined by Stu L., Hank V., and Steve R that the 2005 PSS DO data was off. They came up with the following to correct:

*** corrected 2005 PSS DO = 1.2352*(old 2005 PSS DO) + 0.2847 *** On 2/6/06, All 2005 cruises were re-run with this correction.

The raw data files contain all of the data. The summary files average some of the values within 1-sec intervals.

ESD = equivalent spherical diameter:
BIN 1 Range: 0.25mm - 0.50mm
BIN 2 Range: 0.50mm - 1.00mm
BIN 3 Range: 1.00mm - 3.00mm

Reference:

Ruberg, S.A., H.A. Vanderploeg, J.F. Cavaletto, G.A. Lang, J.R. Liebig, T.C. Miller. 2001. Plankton Survey System. Oceans 2001 MTS/IEEE Conference Proceedings. Pp. 1899-1903.

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