Data Checks and Processing Performed by CDIAC
An important part of the numeric data packaging process at the Carbon Dioxide Information Analysis Center (CDIAC) involves the quality assurance (QA) of data before distribution. Data received at CDIAC are rarely in a condition that would permit immediate distribution, regardless of the source. To guarantee data of the highest possible quality, CDIAC conducts extensive QA reviews that involve examining the data for completeness, reasonableness, and accuracy. The QA process is a critical component in the value-added concept of supplying accurate, usable data for researchers.
The following information summarizes the data processing and QA checks performed by CDIAC on the data obtained during the R/V Knorr cruise along WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2 in the Indian Ocean.
- The final carbon-related data were provided to CDIAC by the ocean carbon measurement PIs listed in Table 5. The final hydrographic and chemical measurements and the station information files were provided by the WOCE Hydrographic Program Office (WHPO) after quality evaluation. A FORTRAN 90 retrieval code was written and used to merge and reformat all data files.
- Every measured parameter for each station was plotted vs depth (pressure) to identify questionable outliers using the Ocean Data View (ODV) software (Schlitzer 2001) Station Mode (Fig. 3).
- The section plots for every parameter were generated using the ODV's Section Mode in order to map a general distribution of each property along all Indian Ocean sections (Fig. 4).
- To identify "noisy" data and possible systematic, methodological errors, property-property plots for all parameters were generated (Fig. 5), carefully examined, and compared with plots from previous expeditions in the Indian Ocean.
- All variables were checked for values exceeding physical limits, such as sampling depth values that are greater than the given bottom depths.
- Dates, times, and coordinates were checked for bogus values (e.g., values of MONTH < 1 or > 12; DAY < 1 or > 31; YEAR < 1994 or > 1996; TIME < 0000 or > 2400; LATITUDE < 70.000 or > 60.000; LONGITUDE < 19.000 or > 119.000.
- Station locations (latitudes and longitudes) and sampling times were examined for consistency with maps and cruise information supplied by PIs.
- The designation for missing values, given as -9.0 in the original files, was changed to -999.9 for the consistency with other oceanographic data sets.