Data Checks Performed by CDIAC
An important part of the numeric data package (NDP) preparation 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. Reviews involve examining the data for completeness, reasonableness, and accuracy. Although they have common objectives, these reviews are tailored to each data set, often requiring 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 summarizes the data processing and QA checks performed by CDIAC on the data obtained during the 1986-1989 PMEL cruises in the Pacific and Indian Oceans.
- These data were provided to CDIAC as twelve ASCII-formatted files with accompanying printed documentation (NOAA Technical Memorandum ERL PMEL-101). A FORTRAN 77 retrieval program was written and used to reformat the original twelve files into twelve files with identical formats and to merge all data into a single file that was sorted and arranged chronologically.
- All data were plotted to check for obvious outliers.
- Dates, times, and coordinates were checked for bogus values (e.g., values of DAY <1 or >31; YEAR <1986 or >1989; DAYGMT <1.000 or >365.999; LAT <-90.000 or >90.000; LONG <-180.000 or >180.000).
- All cruise tracks were plotted and compared with the maps and cruise information supplied by Murphy et al. (1994).
- The data quality flags for missing values, given as "-99" in the original data files, were changed to "5". The data accuracy quality flags, also given as "-99" in the original data files, were changed to "2". These changes reflect the quality flag definitions specified by the WOCE Hydrographic Program (WHP) Data Reporting Requirements (1991). Under these guidelines, "5" and "2" denote "data not reported" and "acceptable measurements", respectively.
- The designation for missing values, given as "-99.00" in the original files, was changed to "-999.9".