Implementation of Quality Flags in the Processing of High Frequency Radar Surface Current Data

The Mid-Atlantic Regional Association Coastal Ocean Observing System (MARACOOS) produces hourly regional surface current maps for an area of coastal ocean stretching from the Outer Banks to Cape Cod. An updated and more formal implementation of quality control (QC) in the real-time processing has been tested over the past year using QC tests described in the QARTOD Manual for Real-Time Quality Control of High Frequency Radar Surface Current Data. Quality checks are performed at spectra, radial and total vector levels of processing. At the radial and total vector levels, primary and secondary flags are written to the data files. The primary flag is intended to provide data users with an overall assessment of data quality that can be used to quickly filter out bad data. The secondary flags are the results of individual QC tests and provide information that the radar operator(s) could use to address specific quality issues in order to improve the real-time data feed. An analysis of the flag information recorded in the radial and total vector files for the time period of March 1, 2021 to May 31, 2021 is presented in this paper. Percentages of over-water radial vectors that fail the QC tests are typically under 10%. The valid location test fails more radials than other tests followed by the spatial median test, the radial count test and the syntax test. A comparison of test failures is made between thirteen different radar stations. Details are provided on how QC test thresholds are assigned. Finally, the impact of the quality control on the surface current maps is described.