National Data Buoy Center Presented to the QARTOD III Workshop November 2, 2005 Wave Data Quality Control Chung-Chu Teng

National Data Buoy Center NDBC Wave Measurement systems 96 buoys (35 directional waves) and 4 C-MAN stations

National Data Buoy Center Katrina

National Data Buoy Center Station 42003

National Data Buoy Center Station 42003

National Data Buoy Center Station 42040

National Data Buoy Center Station 42040

National Data Buoy Center Station 42007

National Data Buoy Center Station 42007

National Data Buoy Center Sensor Evaluations Individual Sensor Calibrations Payload Testing System Lab Testing Blue-tag System Testing Burn-In Data Evaluation at deployment Data Quality Control: The Last Line of Defense, after…

National Data Buoy Center FPSN7 vs m Discus moored next to FPSN7 3-m to replace FPSN7 Interesting, but limited data comparison

National Data Buoy Center FPSN7 vs Wave Height

National Data Buoy Center Performed On: –NDBC and Regional Observatory Data Consists Of: –Automated Real-Time Checks –Man-Machine Mix Outputs: –Withhold, adjust real-time data NOTICE: Users don’t see flags –Archive Data Set Data Quality Control

National Data Buoy Center Quality Control Process Flow Real-Time: –Message Integrity –Automated Hard-Flag –Automated Soft-Flag Post-Release, Pre-Archive: Data Analyst

National Data Buoy Center Quality Control of Wave Data No QC Done Onboard the Buoy Handbook of Automated Quality Control Checks and Procedures of the National Data Buoy Center Automated QC Done in Real-Time at NWSTG Hard-flags: – Stop the Release and Archive of Data unless Analyst Overrides. Override in advance – Storm Limits Remove before archive –Hierarchical: Order of Precedence, Fail One and Stop Soft-flags: Warning

National Data Buoy Center Hard-Flags by hierarchy - highest to lowest: T Transmission parity error M Missing sensor data W wave message is short, checksum or parity errors. E Calculation limits are exceeded or are in error D Delete measurement S Invalid statistical parameter V Failed time continuity. L Failed range limits. R Related measurement has failed a hard QC check.

National Data Buoy Center Time Continuity Check Dependent on time since last valid observation. Max. allowed value = 0.58*Std.dev.*SQRT(TimeDiff) Std. dev. Chosen 50% higher climatic standard dev. within a month Only Applied to Wave Height

National Data Buoy Center If data fails time continuity, it may still be released if: Wave Height: Current wind speed > 15 m/s Storm Limits: Allows Release of Failed Time Continuity with Approach of a Hurricane, or Storm of the Century

National Data Buoy Center The tie between range and time continuity checks If WVHGT fails for two consecutive hours, no measurements will be sent until analyst reviews (D-flag) Measurements should still be sent if it fails a range check, unless it failed a time continuity check the previous hour.

National Data Buoy Center Soft-flags for Waves a: Measurement is above monthly, regional limit. b: Measurement is below monthly, regional limit. c: Measurement has been adjusted, or corrected. f: Measurement failed hourly time continuity. m: High frequency spikes detected in the wave spectrum. p: Failed wave height to wave period comparison test. q: Swell direction is from an improbable direction. w: Failed wind direction verses wave direction check. x: Wind wave energy is too high for prevailing wind speed. y: Wind wave energy is too low for prevailing wind speed.

National Data Buoy Center x and y flags:

National Data Buoy Center Post-Release Analysis Wind vs Wave Energy Scatterplots Ad-hoc Comparisons with NCEP WWIII Check-Ratio at 0.1, 02., and 03. Hz

National Data Buoy Center Wind-Wave Scatterplot

National Data Buoy Center Time Series Mean Acceleration or Displacement within Limits (L-flag) and Not Outside of Max/Min (S-flag)

National Data Buoy Center NDBC QC Table

National Data Buoy Center NDBC Web Page 20 Million Hits/Month

National Data Buoy Center NDBC Stations and Data Peering into the Future… More stations –More buoys and C-MAN stations (96 and 57) –DART buoys (from 6 to 39) –TAO buoys (55 + 4) More measurements: directional waves, current (surface or profile), CT (surface or profile), and other oceanographic and climate data. Multipurpose systems and stations Data Management and Communication (DMAC) – including NDBC Data Assembly Center New technology and systems