Data Quality Control
The objective behind the quality control procedures and techniques is that all sensors should perform within stated accuracies. The quality control procedures used by NDBC fall into two categories: completely automated and those that involve a man-machine mix. The completely automated procedures are performed at NWSTG for real-time messages used for operational forecasts and warnings. The other procedures are performed at NDBC for data that is submitted for archival.
The real-time automated procedures, performed at NWSTG, check to eliminate gross errors. Transmission parity error, range limit, and time continuity checks are performed. Relational checks, such as examining the wind gust to wind speed ratio, are performed to check the quality of both measurements. Another check ensures that the battery voltage is adequate for barometric pressure measurements.
At NDBC stricter range and time continuity limits are performed. Measurements from duplicate sensors are compared to ensure that they track together. NDBC also uses a man-machine mix of quality checks, such as graphical procedures which relate wind speed and spectral wave energy. Other man-machine procedures involve time series plots, spectral wave curves, and computerized weather maps.
When sensor or system degradation is detected, the affected data are removed before posting on the NDBC Web site or archival. The real-time processing at NWSTG is instructed to not release data from the degraded sensor.
For more detailed information regarding NDBC's quality control techniques, refer to:
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NDBC, 2009: NDBC Technical Document 09-02, Handbook of Automated Data Quality Control Checks and Procedures
Gilhousen, D.B.,1998: Improved Real-Time Quality Control of NDBC Measurements. Preprints of the 10th Symposium on Meteorological Observations and Instrumentation, Phoenix, AZ 363-366.
Gilhousen, D.B., 1988: Quality control of meteorological data from automated marine stations. Preprints of Fourth International Conference on Interactive Information and Processing Systems for Meteorology, Oceanography, and Hydrology, Miami, FL, 113-117
Gilhousen, D.B., 1987: A field evaluation of NDBC moored buoy winds. Journal of Atmospheric and Oceanic Technology, 4, 94-104.
Copies of these documents can be obtained by contacting NDBC's Technology Development Division.