Quality Assurance and Quality Control Processes for Current Measurements From USCG ATONs

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Quality Assurance and Quality Control Processes
for Current Measurements From USCG ATONs
Jennifer Dussault Qartod II February 28,2005
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PORTS is a NOAA program that provides mariners
with accurate information to improve safety and
efficiency of maritime commerce
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A TYPICAL PORTS SITE PROVIDES
1-866-CH-PORTS

• Predicted and observed water levels
• Meteorological information including wind speed
  and direction, barometric pressure, air
  temperature
• Predicted and observed currents
• Water density, salinity/temperature
• Access to the data in graphic and text format via
  internet, and voice
• All data are updated at 6-minute intervals
• All data are quality controlled

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WHY PUT CURRENT METERS ON ATONs ?
Underwater cable to shore has long been a PORTS
operations weak link
Maritime community requires current information
within navigation channels
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Not to Interfere CONSIDERATIONS

• Deployed/recovered with buoy on station
• Entire package removed prior to ATON servicing
• All similar metals
• and coloration
• Minimal alteration
• of buoy profile
• and characteristics

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USCG Approval

• Total package weighs 195 lbs
• lt 0.1 estimated lowering of buoy optics
• lt ½ deg estimated buoy tilt
• Completely battery powered

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THE CLAMPARATUS
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DAVID TAYLOR TESTINGNovember 2002

• All Nortek Aquadopps are tow-tested at David
  Taylor before operational use, as required by
  CO-OPS policy

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The mean difference using bin two was 0.0903 m/s
and the mean difference using bin four was 0.0577
m/s
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BUOY 2C
Prototype Installed 17 December 2002
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BUOY 2C - DIRECTION
One month of current meter data were compared to
predictions from a station ¾ mile away Compass
problem became obvious immediately
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COMPASS CALIBRATION IN THE LAB
Nortek designed and installed a firmware
enhancement which allows compass
calibration Several tests were performed in the
lab and on a buoy at the USCG yard
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COMPASS CALIBRATION IN THE FIELD
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AFTER CALIBRATION
Examine 5 day slices of directions Black
Bottom Mount Red ATON Blue difference

• Encouraging
• Flood and ebb occur together, with similar
  time/direction characteristics
• Largest differences occur at the change of tide
  when the currents are weak and variable.

• Discouraging
• There is no clear pattern, the ATON is not
  always higher/lower on flood/ebb.

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PINEY POINT ATON vs BOTTOM MOUNTCURRENT
COMPARISON
Mar 18th Apr 6th 2004 Bottom Mounted RDI 600
KHz WH 1m bins ATON Mounted Nortek 1 MHZ Aquadopp
1 m bins
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3 bins surface (3.5 m/11.5 ft) mid depth
(9.5m/31.2 ft) bottom (15.5 m/44.3 ft) Speeds
compare very well, within anticipated error of
individual instruments No obvious bias in
ATON Mean difference 3cm/s 0.06 knots
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ATON measurements are noisier at all levels due
to buoy motion. ATON has on the order of 10X
larger vertical velocity in the uppermost bins.
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Seeking a parameter that correlates well with the
difference in direction between the Bottom Mount
and ATON. This is the mid depth signal.
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Direction Difference vs Buoy Heading
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Direction Difference vs Current Direction
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Direction Difference vs Buoy Pitch
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FREEPORT, TX ATON vs BOTTOM MOUNT CURRENT
COMPARISON
January 13 May 4, 2004 Bottom Mount RDI 600
KHz WH 1m bins ATON Mount Nortek 1 MHZ Aquadopp
1 m bins
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Again speeds compare very well, with no obvious
bias Mean difference 3 cm/s 0.06 knots
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Again focusing on direction Black Bottom
Mount Red ATON Blue difference
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• Mouth of the Freeport River is in the Gulf of
  Mexico
• Not tidally dominated
• Large directional differences at times current
  reversal

Difference in direction between the Bottom Mount
and ATON clearly decreases with increasing
current speed.
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BUOY 2CH ATON vs HULL-MOUNTED CURRENT COMPARISON
R/V Fay Slover moored at 2CH One complete tidal
cycle 17-18 May 2004 Hull-mount RDI 600 KHz WH
1 meter bins ATON Mount Nortek 1 MHZ Aquadopp 1
m bins
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GPS COMPASS CALIBRATION IN THE LAB
November 2004, and February, 2005
Goals Rotate GPS compass and Nortek to determine
the effectiveness of the Nortek compass
calibration algorithm Evaluate potential for GPS
compass calibration of the Nortek
Thales GPS Compass 10 Hz compass sampling rate, 1
sec average Nortek 1 sec compass sampling rate
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GPS COMPASS TEST IN THE LAB, PART I
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GPS COMPASS TEST IN THE LAB, PART II
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GPS COMPASS TEST ON ATON 14
Large differences correlate to times when the
buoy was turning quickly GPS and Nortek were not
aligned (261 degree offset) Plan another test
for an entire tidal cycle Make mount to raise
GPS antenna above the ATONs solar panel Plan to
study how slow you need to rotate the GPS to
reduce error
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QA/QC WHATS NEXT ?
Continued GPS testing Long term comparison of
ATON and bottom mount at an existing PORTS station
Refine compass calibration procedure
Find a method for removing fake w
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Ocean Systems Test and Evaluation Program NOAAs
Ocean Service Center for Operational
Oceanographic Products Services www.tidesandcurr
ents.noaa.gov
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