Data processing:
LabVIEW (version 16.0) was used to automate the syringe pump and read the R value obtained from the spectrophotometer and approximate pH value prior to corrections. Salinity corrections were later applied using corresponding GEOTRACES bottle data. Dye corrections were later applied using the method of Clayton and Byrne (1993) using intercalibration samples provided by Andrew Dickson's lab at UCSD.
Two reference materials (B162 and B164) from Andrew Dickson's lab at UCSD were used to evaluate the uncertainty of our pH results collected at sea. pH values of 7.9143±0.0065 and 7.5532±0.0030 were recorded, in comparison the reported values for these reference materials were 7.9100±0.0005 and 7.5407±0.0010, respectively (Bockman and Dickson, unpublished). This translates to a 99.95% agreement for B162 and a 99.83% agreement for B164.
Known Problems:
For all of Station 27 and half of Station 29, the pH measurements are not trustworthy due to an error with the light source resulting in greater fluctuations of the λ434 absorbance reading (data are flagged 4). The integration time was increased, and the attenuator adjusted to fix this problem.
Quality Flags:
The SeaDataNet scheme was used to assign data quality flags to samples. More information can be found at https://www.seadatanet.org/Standards/Data-Quality-Control.
The reported codes for flagged data are:
0 = no quality control;
1 = good value;
2 = probably good value;
3 = probably bad value;
4 = bad value;
5 = changed value;
6 = value below detection;
7 = value in excess;
8 = interpolated value;
9 = missing value.
For intercalibration procedures, refer to the dataset's GEOTRACES Intercalibration Report (PDF).
BCO-DMO Processing:
- modified parameter names;
- added date/time fields in ISO8601 format.
Version history:
2021-05-06 (v2; current) - version 2 processed & published; includes corrections to sample numbers.
2021-01-26 (v1) - version 1 processed & published.
BCO-DMO Blog
©2024 Biological and Chemical Oceanography Data Management Office.
