Current measurements from a deep real-time metocean mooring: lessons learned on real-time data QA/QC

An automated Quality Assurance and Quality Control (QA/QC) procedure implemented by Woods Hole Group, Inc. (WHG) to improve the quality of ADCP data collected on a deep Real-Time Metocean Mooring (RTMM) is described. The RTMM is equipped with three TRDI ADCPs and one Nortek single-point current meter (SPCM). A full water column current profile is collected every 20 minutes and the data are sent by satellite to a shore-based computer and web server, which creates graphical displays in near-real-time and serves them over the Internet to user´s web browsers. WHG´s automated QA/QC procedure was developed based on analysis of a first batch of ADCP data collected by the RTMM and is system-specific. The analysis of the data and of data quality indicators revealed major causes that lead to the occurrence of spurious and/or noisy current data. It also suggested approaches to improving the quality of the data provided to the client in near-real-time. The analysis revealed certain limitations of the QA/QC algorithm implemented by NDBC and recommended by QARTOD. From our experience with the RTMM data, the QA/QC of ADCP data should not be limited to automated review of quality parameters measured by the ADCP on individual ensemble-averaged profiles. A better result is achieved by adjusting ADCP setup and customizing data screening thresholds for a specific deployment. The thresholds should be customized based on the analysis of the system-specific data.