Post on 04-Jan-2016
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DATA QUALITY CONTROL
Julie ThomasCoastal Data Information Program (CDIP)
Scripps Institution of Oceanography
CI Design Workshop17-19 October 2007
La Jolla, CA
ACTQARTOD
REAL-TIME CASE STUDY
INTERNATIONAL EFFORTS
WMO, OceanSITES/Eurosites/IFREMER, JCOMM, ……..
Directional Wave Observations1) The Basics
2) Remote Sensing v. In Situ : It’s all good.
3) Estimating directional wave properties.
4) Measurement accuracy and user needs.
5) A Recipe for instrument evaluation.
ALLIANCE FOR COASTAL TECHNOLOGIES
ACTWave Sensor Technologies
University of South Florida, March 7-9 2007By Bill O’Reilly
z
xy
w
u
v
The Big 3
X, Y, Z
The Basics: Estimating the Motion of a Sea Surface Particle
Pressure SensorsAccelerometersTilt sensorsAngular Rate SensorsAcoustic SensorsRadarLidar
dz/dx,dz/dy
z
In-Situ and Remotely Sensed Waves
MethodO(cm) X,Y,Z Accuracy
SpatialCoverage
Time Coverage
In situ
SAR,LIDAR
HF, X-Band Radar
In situ and remote sensing systems are complimentary, NOT redundant.
XYZ TIME SERIES
The Big 3: X, Y, Z Time Series Analysis The First 5: S(f),a1(f),b1(f),a2(f),b2(f) !!
S
Theoretical maximum level of breaking wave in a fully developed sea
Each box represents the number of hourly observation – Datawell Buoy Mark II w/ hippy used as data source (standard).
Comparison between a Datawell Buoy w/ hippy and a PROTOTYPE Datawell w/ GPS. Low numbers indicate good correlations. InstrumentsWere co-located.
GPS instrument dropped out during low Frequency – causing spikes in data
Instruments tend to disagree asthey are interpreting sea surface differently under breaking wave conditions.
Datawell w/ hippy and Datawell w/ GPS tend to agree well with wave direction. Note how both instruments reach their noise floor during long period, low energy events.
Directional spread is where many instruments fall apart! Good indication of the quality of the instrument – demonstrates their directional noise level!
GPS antenna on top of the buoy has a “natural” noise when it wobbles – a method has been devised to correct for this problem.
QUALITY ASSURANCE OF REAL-TIME DATA
QARTODhttp://qartod.org
QARTOD is a continuing multi-agency effort to address the Quality Assurance and Quality Control issues of the Integrated Ocean Observing System (IOOS) and broader international community.
Quality Control standards have been submitted to DMAC for both waves and Currents. Ocean.US is now soliciting submissions from the Regional Associations for all standards including QA/QC. The QARTOD submissionsWill be posted soon on the Ocean.US website.
Parameters addressed through QARTOD: Waves, In-situ Currents, Remote Currents (HF RADAR), CTDs, Dissolved Oxygen.
Collaborated with DMAC Metadata team for a one day appended workshopDuring QARTOD IV, June 2006.
http://qartod.orghttp://cdip.ucsd.edu/documents/index/product_docs/qc_summaries/waves/waves_table.php
Quality Assurance (QA) – Verify that instrumentation is calibrated and tested to assure collection of the highest qualitydata possible.
Quality Control (QC) – Analyze and verify the data streamto assure the highest quality datapossible.
VALIDATION CASE STUDY - Real-time Buoy Data
Eel RiverCape Mendocino (094)
Humboldt Bay South Spit (128)
OREGON
CALIFORNIA
NDBC BUOY 46022, EEL RIVER, re-deployed this summer with 3DMG sensor. 46022 is 34 miles away from buoy 46213 (CDIP Datawell Buoy Station 094).
Full spectra looks ok at first glance!
Under predicts LONG PERIOD SWELL (12-33 sec)
Noisy directional spread
Comparison of the Datawell /hippy and the NDBC 46022 (Eel River Buoy) w/ 3DMG sensor .
46022 under predicts low frequency waves.
Buoys are moored 34 miles apart. Part of this difference in the high frequency could be caused by local sea conditions.
Why is directional spread important? Why do we need accurate wave measurements?
The models are only as good as their input source.
In Southern California, for instance, 5 degrees can makea big difference in how much energy reaches the beach.
Let’s come together as an IOOS community and further validate our wave instrumentation!