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Exploring Puget Sound Tides & Currents with the . Acoustic Doppler Current Profiler (ADCP) Paul A. McWilliams. Presentation Outline. Tides (Sat & Fri) Predicted Currents The ADCP Data Samples Contours Profiles Questions. Saturday May 8 Spring Ebb Range=13.3ft Low 2:07 AM 7.2
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Exploring Puget Sound Tides & Currentswith the Acoustic Doppler Current Profiler (ADCP) Paul A. McWilliams Paul McWilliams – Ocean 101 Spring 2004
Presentation Outline • Tides (Sat & Fri) • Predicted Currents • The ADCP • Data Samples • Contours • Profiles • Questions Paul McWilliams – Ocean 101 Spring 2004
Saturday May 8 Spring Ebb Range=13.3ft Low 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=5.2ft High 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 Tides for 8 &14 May, 2004 Paul McWilliams – Ocean 101 Spring 2004
Ebb Tide (Sat) Expected Flow • North in central Puget Sound • South from Possession Sound • West Through Admiralty Inlet Paul McWilliams – Ocean 101 Spring 2004
Flood Tide (Fri) Expected Currents • East through Admiralty Inlet • South in Central Sound • North in Possession Sound Paul McWilliams – Ocean 101 Spring 2004
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 Current Predictions Paul McWilliams – Ocean 101 Spring 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 101 Spring 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 101 Spring 2004
Three Types of Displays • Contour • Detail Contour • Profile Paul McWilliams – Ocean 101 Spring 2004
6 Types of Data • Direction • Magnitude • North Velocity • East Velocity • Error • Vertical Paul McWilliams – Ocean 101 Spring 2004
GPS Navigation Processing Friday PM leg Contours without and with (bottom) Navigation Processing Paul McWilliams – Ocean 101 Spring 2004
Direction Contours Sat (Top) versus Fri (Bottom) Color Code: Magenta=North Blue=East Green=South Orange=West Paul McWilliams – Ocean 101 Spring 2004
Magnitude Contours Saturday (top) Versus Friday (bottom) Color Code: Magnitude (mm/s) Red=700 Blue=0 Paul McWilliams – Ocean 101 Spring 2004
North Velocity Saturday (top) Versus Friday (Bottom) Color Code: Warm=“+”or N Cool=“–”or S +/-700mm/s Paul McWilliams – Ocean 101 Spring 2004
East Velocity Saturday (top) Versus Friday (Bottom) Color Code: Warm=“+”or E Cool=“–”or W +/-700mm/s Paul McWilliams – Ocean 101 Spring 2004
Profile Examples-Max Ebb • Saturday • Taken @ West Point • 10:36am Velocity Green”+”=N Red”+”=East Paul McWilliams – Ocean 101 Spring 2004
Profile Examples-Max Flood • Friday • Taken @ Edmonds • 12:13pm Velocity Green”+”=N Red”+”=East Paul McWilliams – Ocean 101 Spring 2004
Profile Examples-Friday Cast 3 • Friday • Taken @ ORCA 2 • 3:40pm (high slack) Velocity Green”+”=N Red”+”=East Paul McWilliams – Ocean 101 Spring 2004
Questions? For More Information: http://students.washington.edu/paulmcqm/ocean_cruise.htm Paul McWilliams – Ocean 101 Spring 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 Paul McWilliams – Ocean 101 Spring 2004