Sea-Bird Scientific SUNA V2, User Manual

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• The default "Enable Raw Data Checksum Validation" is on, with a check in the box. If
it is turned off, raw data can be processed even when the checksum values have
changed after data is collected.
• The default "Fitting Range" is 216.5–240 nm. If the wavelength is shorter, seawater
typically causes extinction, and a poor signal-to-noise ratio. If the wavelength is
longer non-characterized materials can be absorbed, which causes a bias in the
processed concentrations.
• The default "Max Absorbance Threshold" is 1.3. The precision of the measured
absorbance starts to decline at this value. At 2.5 absorbance units, the precision is at
the "noise floor." The precision of the processed data is better when the low-quality
parts of the "fitting range" are not processed.
• The default Seawater Calibration has no check in the box at "Deployed in Fresh
Water." Put a check in this box if the sensor was calibrated for seawater but deployed
in fresh water. Data that was collected in seawater with a check in the "Deployed in
Fresh Water" box gives incorrect nitrate concentrations.
Temperature and salinity correction
Seawater has a temperature-dependent absorption rate. Make sure to consider this so
that imprecision does not affect the nitrate concentration that is measured. To mitigate
this effect, use the sample temperature and salinity values in the nitrate calculation in the
host software for post-processing. Note that spectra and related temperature and salinity
data is necessary. The temperature-salinity correction comes from MBARI (cf. Carole M.
Sakamoto, Kenneth S. Johnson, and Luke Coletti, Limnol. Oceanogr.: Methods 7, 2009.)
"Temperature and Salinity Correction" is available if the sensor is calibrated for seawater
and water temperature and salinity data ("T-S data") are collected. This data can come
from frames if the sensor operates in APF mode (SUNA V2 deep only), or from an
external file.
1. The default "Activate Temperature & Salinity Correction" has no check in the box. Put
a check in this box to add T-S data correction information.
2. Select either "CTD Data from SUNA APF Mode Frames" or "Data from External File"
to get T-S data from an external file. The required ASCII format is "YYYY-MM-DD
hh:mm:ss, Temperature (c), Salinity (PSU)" e.g. 2012-11-10 90:08:06,12.3,34.567.
3. Push Browse to find the file. For "External Files": at the bottom of the new window
choose either "Sea-Bird CNV Data File" or "CSV Data File" in the "Files of type:"
area. Push
Open . A green check will show in the T-S Correction area of the software
when the data is loaded.
4. The data files must have the same time stamp if more than one is selected. If
necessary, put a value in the "Time Offset" area to align the time stamps.
Transmit data
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