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Towards a Standard for Real-time Quality Control Procedures for in situ Ocean Waves

Establishing standards for quality control procedures for in-situ ocean waves in real-time to ensure accuracy and consistency in data assimilation and application. Learn about QARTOD, proven practices, and quality assurance techniques. Presented at QARTOD to OGC in 2008.

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Towards a Standard for Real-time Quality Control Procedures for in situ Ocean Waves

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  1. Towards a Standard for Real-time Quality Control Procedures for in situ Ocean Waves Richard Bouchard1 and Julie Thomas2 NOAA’s National Data Buoy Center Coastal Data Information Program/Scripps Institution of Oceanography Presented at QARTOD to OGC (Q2O) February 2008 Photo courtesy of NWS Portland, OR

  2. Motivation for Standard • Need simple, proven, and consistent quality descriptions as more new observing systems arise and more observations are exchanged and integrated • Real-time -> users need an expected level of quality assurance for rapid assimilation and application

  3. Procedures Development • Quality Assurance of Real-Time Oceanographic Data (QARTOD) - http://www.qartod.org • Sponsored by NOAA • Four workshops 2003 – 2006 and the Waves Technical Workshop – 2005 • Waves Working Group – government, academia, commercial, research, operational

  4. Proven Practices • Coastal Data Information Program (CDIP) http://cdip.ucsd.edu/?nav=documents&sub=index&xitem=proc#quality • NOAA/National Data Buoy Center http://www.ndbc.noaa.gov/handbook.pdf (QC) http://www.ndbc.noaa.gov/wavemeas.pdf • US Army Corps of Engineers, Nortek, SonTek/YSI, Teledyne RDI • UNESCO/IOC/IODE & MAST, 1993: Manual of Quality Control Procedures for Validation of Oceanographic Data – useful, but dated

  5. Series of Tests • Tests applied to the: • Time Series, • Wave Spectra, and • Bulk Parameters (e.g., height, period) • Flagging convention: QC indicator • Hard flag stops the release of data • Soft flag is warning • Some parameters have tests with both hard and soft flagging criteria • Original flag coding abandoned – at odds with existing conventions • QARTOD Results and Proven Practices: http://cdip.ucsd.edu/qartod/waves_qc

  6. Submitted to IOOS Data Management and Communications Steering Team as a Possible IOOS Standard Submitted standard can be viewed at: https://ioosdmac.fedworx.org (login required), or http://nautilus.baruch.sc.edu/twiki/bin/view/Main/WaveQC QARTOD Results Refined by • Response to Request for Comments • DMAC ST Standards Requirements • Comments from DMAC Steering Team

  7. Detailed Description: Check Ratio Scope or Applicability: Heave/Slope (pitch and roll) Buoys. Description The check ratio or check factor, R, is loosely defined as the ratio of vertical to horizontal wave orbital motions. R is more formally defined by: where: C11, C22, and C33 are the cross-spectra respectively of heave, pitch, and roll. k is the wave number, h is the water depth, and tanh is the hyperbolic tangent function. This check ratio is a function of frequency and depth. It should theoretically be 1 for relatively deep water waves, but tends to deviate substantially from that value at periods longer than the peak frequency, and at short periods outside the response range of the buoy. The data provider may choose any of the following methods of the check ratio test: • Computed at the peak wave energy period and at a short period (but within the surface-following capability of the buoy) flag values outside the range of 0.9 to 1.1, or • Test at least three frequencies distributed one each in the low, mid, and high frequency ranges, or • Compute the percentage of all frequencies whose check ratio is within acceptable limit of 1.0, and flag if the percentage is outside of an established criterion. Sources: CDIP, 2003. Krogstad, H.E., 2001. Steele et al. 1992. UNESCO, 1993. Check 3.2.4, Check Factor. USACE FRF, 2007. Current Usage CDIP, USACE FRF, and NDBC.

  8. Contacts • Richard Bouchard, NOAA/NDBC richard.bouchard@noaa.gov • Julie Thomas, CDIP jot@cdip.ucsd.edu • Anne Ball, DMAC ST anne.ball@noaa.gov

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