Paul McWilliams – Ocean 101 Spring 2004 Exploring Puget Sound Tides & Currents with the Acoustic Doppler Current Profiler (ADCP) Paul A. McWilliams
Jan 21, 2016
Paul McWilliams – Ocean 101Spring 2004
Exploring Puget Sound Tides & Currents
with the
Acoustic Doppler Current Profiler (ADCP)
Paul A. McWilliams
Paul McWilliams – Ocean 101Spring 2004
Presentation Outline
1. Tides (Sat & Fri)2. Predicted Currents3. The ADCP4. Data Samples
• Contours• Profiles
5. Questions
Paul McWilliams – Ocean 101Spring 2004
Tides for 8 &14 May, 2004
Saturday May 8• Spring Ebb• Range=13.3ftLow 2:07 AM 7.2
High 6:53 AM 10.4
Low 2:17 PM -2.9
High 10:04 PM 11.5
Maximum Ebb ~10:36AM
Friday May 14• Neap Flood &
LHW• Tidal Range=5.2ftHigh 2:33 AM 11.1
Low 9:10 AM 2.8
High 3:10 PM 8.0
Low 8:33 PM 3.5
Max Flood ~12:13pm
Paul McWilliams – Ocean 101Spring 2004
Ebb Tide (Sat)
Expected Flow• North in central
Puget Sound• South from
Possession Sound• West Through
Admiralty Inlet
Paul McWilliams – Ocean 101Spring 2004
Flood Tide (Fri)
Expected Currents• East through
Admiralty Inlet• South in Central
Sound• North in
Possession Sound
Paul McWilliams – Ocean 101Spring 2004
Current Predictions
Saturday May 8• Stronger
Currents• Northward Flow
during Ebb Tide• Westward Flow in
the near Edmonds
Friday May 14• Weaker Currents• Southward flow
during Flood Tide
Paul McWilliams – Ocean 101Spring 2004
Acoustic Doppler Current Profiler (ADCP)
• Uses compression and expansion of reflected sound-waves to measure the movement of particles in the water
• Requires significant Processing power-Microprocessors Make Possible
• Must take Ship’s Motion into account (GPS)
Paul McWilliams – Ocean 101Spring 2004
ADCP Limitations
• Cannot “see” bottom 15% of Water Depth or Near Surface– Backscatter– Surface Noise
• GPS Precision—Ship’s Pitch and Roll not Accounted For
Paul McWilliams – Ocean 101Spring 2004
Three Types of Displays
• Contour• Detail Contour• Profile
Paul McWilliams – Ocean 101Spring 2004
6 Types of Data
• Direction• Magnitude• North Velocity• East Velocity• Error• Vertical
Paul McWilliams – Ocean 101Spring 2004
GPS Navigation Processing
Friday PM leg Contours without and with (bottom) Navigation Processing
Paul McWilliams – Ocean 101Spring 2004
Direction Contours
Sat (Top)versusFri (Bottom)
Color Code:Magenta=North
Blue=East
Green=South
Orange=West
Paul McWilliams – Ocean 101Spring 2004
Magnitude Contours
Saturday (top)VersusFriday
(bottom)
Color Code:
Magnitude (mm/s)
Red=700
Blue=0
Paul McWilliams – Ocean 101Spring 2004
North Velocity
Saturday (top)VersusFriday
(Bottom)
Color Code:Warm=“+”or N
Cool=“–”or S
+/-700mm/s
Paul McWilliams – Ocean 101Spring 2004
East Velocity
Saturday (top)VersusFriday (Bottom)
Color Code:Warm=“+”or E
Cool=“–”or W
+/-700mm/s
Paul McWilliams – Ocean 101Spring 2004
Profile Examples-Max Ebb
• Saturday • Taken @ West
Point• 10:36am
VelocityGreen”+”=N
Red”+”=East
Paul McWilliams – Ocean 101Spring 2004
Profile Examples-Max Flood
• Friday • Taken @
Edmonds• 12:13pm
VelocityGreen”+”=N
Red”+”=East
Paul McWilliams – Ocean 101Spring 2004
Profile Examples-Friday Cast 3
• Friday • Taken @ ORCA 2• 3:40pm (high slack)VelocityGreen”+”=N
Red”+”=East
Paul McWilliams – Ocean 101Spring 2004
Questions?
For More Information:http://students.washington.edu/paulmcqm/
ocean_cruise.htm
Paul McWilliams – Ocean 101Spring 2004
Conclusions
• Predictions seems accurate– ADCP seems to work– Currents are strongly
tide based
• Point Wells seems okay for discharge
• Need to look at– full range of tides – Storm conditions