VENUS selects world class instruments from suppliers that the general oceanographic community trusts. We rely heavily on the integrity of the supplier for meeting quality data “standards”. Our approach has not been to try to do any complicated internal checks/re-calibrations, but to monitor, manage, and document the history of these factory calibrations and upon request, make them available to the user. For instance, our primary seawater CTDs are high-end Seabird units that are regularly calibrated by Seabird. Seabird sensors and calibration procedures went through a rigorous evaluation as part of the WOCE program and this reputation, as well as stable calibrations/recalibrations of our instruments, allows us to provide the user the necessary quality assurance they seek.
Quality Control
To date, VENUS data has not undergone significant quality control analysis other than visual checks to determine whether incoming data are within a reasonable range. The “traffic light” system currently in place is meant to warn users of gross errors in the data, but is not indicative of a fully quality-controlled dataset and should be used with caution.
In the near future, VENUS will be implementing automated quality control tests on scalar water sample data. The tests include, but are not limited to:
- Manufacturer’s range tests
- Global water property range tests
- Site water property range tests
These automated tests will flag data as they are received and will be available for VENUS data downloaded in near real-time. Archived data, once put through the same testing scheme, will also be available for download with a QAQC flag. In the future, tests will include statistical tests based on the years of data within each region and will extend to the complex data such as the ZAP or Hydrophone.
The information about the QAQC flag will be detailed via the metadata product provided with each VENUS data product. The included information will describe the tests applied to the data, the values used in the test (i.e maximum/minimum values) and the date range over which the tests are valid. The user can then use the information provided to determine whether further quality control is needed in their research.
