Data Checks and Processing Performed by CDIAC

An important part of the NDP process at the 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. Although they have common objectives, these reviews are tailored to each data set and often require extensive programming efforts. In short, 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 underway data obtained during the R/V Knorr Expeditions in the Indian Ocean (WOCE 9 Sections).

1. All underway measurements were provided to CDIAC as 18 ASCII-formatted files (9 for surface seawater and 9 for marine air CO₂ measurements) by Chris Sabine and Robert Key of PU. A FORTRAN 77 retrieval program was written and used to reformat the original files into uniform formats for "water" and "air" data files.
2. All individual "water" and "air" data files were merged into single "water" and single "air" files that were sorted and arranged chronologically.
3. All data were plotted to check for obvious outliers. Several outliers were identified and removed after consultation with the principal investigators.
4. All data that were marked by quality flag "4" as bad data in original files were removed after consultation with the principal investigators.
5. Dates and times 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.
6. All cruise tracks were plotted using the coordinates presented in data files and compared with the maps and cruise information supplied by C. Sabine and R. Key.