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NDBC Real Time Wave Data Processing and QC/QA. Chung-Chu Teng National Data Buoy Center Stennis Space Center, MS 39529, USA Chung-Chu.Teng@noaa.gov. NDBC Wave Stations. 88 buoys (28 directional waves) and 4 C-MAN stations. NDBC wave measurement capabilities. C-MAN Wave Measurements.

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NDBC Real Time Wave Data Processing and QC/QA


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ndbc real time wave data processing and qc qa

NDBC Real Time Wave Data Processing and QC/QA

Chung-Chu Teng

National Data Buoy Center

Stennis Space Center, MS 39529, USA

Chung-Chu.Teng@noaa.gov

ndbc wave stations
NDBC Wave Stations

88 buoys (28 directional waves) and 4 C-MAN stations

c man wave measurements
C-MAN Wave Measurements

Chesapeake Light

St. Augustine

Diamond Shoal

buoy wave measurements
Buoy Wave Measurements

6-m NOMAD buoy

3-m discus buoy

10-m discus buoy

new stand alone wave system buoy
New Stand-alone Wave System/Buoy

Directional Wave Measurement System:

  • - Small & light
  • Low power consumption
  • Low cost
  • Built-in transmitter
  • Standalone
  • Configurable

Directional Wave buoy:

  • Small & light, deployable from small vessels
  • Low cost
  • Low maintenance

1.8 m COLOS buoy

nomad directional wave measurements
NOMAD Directional Wave Measurements

Use a small directional wave buoy (tether to a 6-m NOMAD buoy or stand-alone)

GOES or Iridium

RF/LOS

communication

c man wave measurements8
C-MAN Wave Measurements

GOES or Iridium

RF/LOS

communication

Deploy a stand-alone directional wave buoy

Install a fixed directional wave sensor on the structure

nondirectional wave data
Nondirectional wave data
  • Wave energy spectrum
  • Wave parameters:

Peak (or dominant) wave period, Tp

Mean (or average) wave period, Tz or Ta

Significant wave height, Hs

S(f)

Frequency, f

buoy wave measurement
Buoy Wave Measurement

Ocean waves

Buoy hull motions

Measurements (Sensors)

Onboard processing

Transmission (or storage)

Shoreside processing

Wave data

nondirectional wave data from buoys
Nondirectional wave data from buoys

From buoy motion to wave data

Sh(f): spectrum of buoy heave motion

Sw(f): wave spectrum (acceleration)

PTF: power transfer function

From acceleration to displacement spectra

noise correction
Noise Correction

S(f)

Low-frequency

noise

Frequency (f)

ndbc directional wave buoy systems
NDBC directional wave buoy systems
  • Based on the “slope following” principle
  • Can only use axis-symmetrical buoys
  • Buoy pitch and roll information are required to determine directional wave data
directional wave algorithm 1
Directional wave algorithm (1)

f : wave frequency; 2 : wave direction

1: vertical motion (heave)

2: N-S slope (pitch)

3: W-E slope (roll)

K: the wave number

C and Q : co- and quad-spectra

directional wave algorithm 2
Directional wave algorithm (2)

θ1 and θ2: mean and principal wave directions

r1 and r2 : directional energy spreading

configurations of ndbc directional wave systems
Configurations of NDBC directional wave systems
  • HIPPY – a gimbaled gyro system that measure pitch and roll directly
  • MO – use only magnetometer outputs to estimate buoy pitch and roll
  • ARS – derive buoy pitch and roll from angular rate sensors
ndbc wave systems
NDBC Wave Systems
  • DACT Wave Analyzer (WA)
  • DACT Directional Wave Analyzer (DWA)
  • VEEP Wave Analyzer (WA)
  • Wave Processing Module (WPM)
  • Directional Wave Processing Module (DWPM)
  • Non-Directional Wave Processing Module (NDWPM)
  • Directional Wave Measurement System (DWMS)
general principles for data qa qc
General Principles for Data QA/QC
  • Reasonability:

Data should be in reasonable ranges and intervals.

  • Continuity:

Data should maintain the continuity in time and space.

  • Consistency (or correlation):

Data should have proper time correlation, spatial correlation, and correlations with other measurements.

some wave data qc techniques
Some wave data QC techniques
  • Range check
  • Time continuity
  • Internal consistency (e.g., QMEAN)
  • Wind vs. wave energy (wind-wave algorithm)
  • Swell direction check
  • High frequency spectral spikes,
  • Wave height vs. average wave period
  • Wave direction vs. wind direction (> 0.35 Hz)
  • When needed, wave data from NCEP’s wave models and other organizations will be used to check its buoy wave data.
hard flags by hierarchy highest to lowest
Hard Flags (by hierarchy - highest to lowest)
  • T Transmission parity error (Applies to continuous winds and non-WPM wave data)
  • M Missing sensor data (A result of a garbled or missing message).
  • W A WPM wave message is short, missing a checksum, or parity errors are detected.
  • E Calculation limits are exceeded or are in error (waves only, flags WVHGT).
  • D Delete measurement from release and archive (A Data Analyst or automated QC has failed the sensor).
  • S Invalid statistical parameter (in waves, QMEAN is not between QMIN and QMAX, flags WVHGT).
  • V Failed time continuity.
  • L Failed range limits.
  • H Hierarchy reversal has occurred (BARO, WSPD, WDIR only).
  • R A related measurement has failed a hard QC check.
soft flags in alphabetical order
Soft Flags (in alphabetical order)
  • a Measurement is above monthly, regional limit.
  • b Measurement is below monthly, regional limit.
  • c Measurement has been adjusted, or corrected (applies to DEWPT and WVHGT, DOMPD and AVGPD).
  • d Failed standard deviation test (continuous winds only).
  • f Measurement failed hourly time continuity.
  • g Failed gust-to-mean wind speed ratio (applies to standard and continuous winds).
  • i Continuous and hourly wind speeds don’t agree.
  • j One, and only one, transmission error detected in the continuous wind string of a GOES message (all continuous wind measurements are flagged, if more than one error detected, than flag is upgraded to a T flag).
  • k Difference between duplicate measurements is too high.
  • m High frequency spikes detected in the wave spectrum (C11), WVHGT is flagged.
  • n Measurement failed comparison with NCEP model fields.
  • p Failed wave height to wave period comparison test.
  • q Swell direction is from an improbable direction.
  • r Related measurement failed (continuous winds only).
  • s Stuck raw compass ( RCOMP and WDIR are flagged).
  • t Tendency difference between duplicate sensors is too high.
  • v Failed relative humidity verses visibility check.
  • 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.
  • z Failed bow azimuth verses wind direction check.
ndbc technical document 03 02
NDBC Technical Document 03-02

Handbook of Automated Data Quality ControlChecks and Procedures of the National Data Buoy Center

February 2003

National Data Buoy Center

Stennis Space Center, Mississippi 39529-6000

range check wave height
Range check (wave height)

Previous EQC limit: 5.2 m (Lakes Erie and Huron)

New EQC limit: 7.5 m