Moorings and Current Meters

1
Moorings and Current Meters

• Ellen Martinsek
• EPS 131
• December 14, 2005

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Outline

• Moorings
• Purpose
• Deployment Recovery
• Specific Projects
• Current Meters
• Different Methods of Measuring Current
• Acoustic Doppler Measurements
• Applications

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Moorings

• Connection between water surface and
  instrumentation in the ocean below the surface

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Deployment Recovery

• Difficult since the mooring cable breaks if moved
  too quickly
• Need to keep instruments and data safe

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Back to WHOI

• Sub-Surface Mooring Operations Group over 90
  instrument and data recovery

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North Pole Environmental Observatory

• First year-round mooring at the North Pole
  retrieved in April 2002
• Purpose to see how the Arctic Ocean influences
  global climate

Retrieving a mooring that has been collecting
oceanographic data from the Arctic Ocean for a
year at the NSFs North Pole Environmental
Observatory Photo Credit Peter West/National
Science Foundation
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Monterey Ocean Observing System (MOOS) test
mooring
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MOOS test mooring

• Biggest engineering problem creating a cable
  that can stay intact!
• 11 days after the first deployment (December 3,
  2002) the cable snapped ? had to redesign it
  before finally redeploying on April 23, 2004.

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Measuring Current

• Mechanical current meters
• Electromagnetic current meters
• Acoustic Travel Time current meters
• Acoustic Doppler measurements

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Acoustic Doppler measurements

• Why sound is good to use
• The Doppler Effect
• Back Scatter Sonar How It Works

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Acoustic Doppler Current Profiler (ADCP)
Constant frequency pings transmitted
Ricochet off suspended particles and reflect back
Calculate speed of particle and surrounding water
using Doppler shift
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Applications of Current Profiling

• Climatic Research
• Ports and Harbors
• Fish Farming
• Pollution Control

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Summary

• Moorings serve as a connection between the water
  surface (which itself is connected via satellite
  to labs onshore) and instruments in the ocean
• An important example of such instrumentation is
  the current profiler in particular, the ADCP

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References

• http//www.pmel.noaa.gov/vents/nemo1999/logbook/ca
  l062399/
• http//www.mbari.org/news/homepage/2004/moosII.htm
  l
• http//www.whoi.edu/institutes/occi/currenttopics/
  ct_oms_stationw.html
• http//www.washington.edu/newsroom/news/2002archiv
  e/05-02archive/npfactsheet.html
• http//www.antarctica.ac.uk/BAS_Science/programmes
  2000-2005/DYNAMOE/Moorings/index.html
• http//walrus.wr.usgs.gov/mcgaw/depmoor.html
• http//pulson.seos.uvic.ca/lecture.html
• http//www.soc.soton.ac.uk/OED/gxg/Single_Point_CM
  s.pdf
• http//www.aanderaa.com/docs/RDCP_600_D343.pdf
• http//www.nsf.gov/od/lpa/news/03/ma0329.htm