User`s manual

Section 4: Configure Inputs, Part II - Calibration Coefficients
42
• Turner SCUFA
Enter scale factor, offset, units, mx, my, and b from the calibration sheet.
chlorophyll = (scale factor * voltage) + offset
corrected chlorophyll = (mx * chlorophyll) + (my * NTU) + b
where
NTU = results from optional turbidity channel in SCUFA (see Turner
SCUFA in OBS equations below)
Note: SEASAVE can process data for an instrument interfacing with up to
two Turner SCUFA sensors.
• WET Labs AC3
This sensor requires two channels - one for fluorometer voltage (listed
under fluorometers in the dialog box) and the other for transmissometer
voltage (listed under transmissometers). Make sure to select both when
configuring the instrument.
Enter kv, Vh2o, and A^X.
concentration (mg/m
3
) = kv * (Vout - Vh20) / A^X
where
Vout = measured output voltage
kv = absorption voltage scaling constant (inverse meters/volt)
Vh20 = measured voltage using pure water
A^X = chlorophyll specific absorption coefficient
• WET Labs WetStar, ECO-AFL, and ECO-FL
Enter Vblank and scale factor.
Concentration (µg/l) = (Vsample - V blank) * scale factor
where
Vsample = in situ voltage output
Vblank = clean water blank voltage output
Scale factor = multiplier (µg/l/Volt)
The calibration sheet lists either:
¾ Vblank and scale factor, OR
¾ Vblank and Vcopro (voltage output measured with known
concentration of coproporphyrin tetramethyl ester). Determine an
initial value for the scale factor by using the chlorophyll
concentration corresponding to Vcopro:
scale factor = chlorophyll concentration / (Vcopro - Vblank)
Perform calibrations using seawater with phytoplankton populations that
are similar to what is expected in situ.
Note: SEASAVE can process data for an instrument interfacing with up to
two WET Labs WetStar sensors.
• WET Labs CDOM (colored dissolved organic matter)
Enter Vblank and scale factor.
Concentration (µg/l) = (Vsample - V blank) * scale factor
where
Vsample = in situ voltage output
Vblank = clean water blank voltage output
Scale factor = multiplier (µg/l/Volt)
The calibration sheet lists Vblank and Vcdom (voltage output measured
with known concentration of colored dissolved organic matter).
Determine an initial value for the scale factor by using the colored
dissolved organic matter concentration corresponding to Vcdom:
scale factor = cdom concentration / (Vcdom - Vblank)
Perform calibrations using seawater with cdom types that are similar to
what is expected in situ.
Notes:
• For complete description of
calibration coefficient calculation,
see Application Note 41 for
WetStar and Application Note 62
for ECO-AFL, ECO-FL, and
ECO-FL-NTU.
• For ECO-FL-NTU, a second
channel is required for turbidity.
Set up the second channel as a
User Polynomial, with:
a0 = - Vblank * scale factor
a1 = scale factor (NTU/volts)
a2 = a3 = 0
where scale factor and Vblank are
for the turbidity measurement.
Notes:
• To enable entry of the mx, my,
and b coefficients, you must
first select the Turner SCUFA
OBS/Nephelometer.
• See Application Note 63 for
complete description of calculation
of Turner SCUFA calibration
coefficients.