Measuring Surface Currents off the Outer Banks of North Carolina

Luke Stearns1, Harvey Seim1, Mike Muglia2

1 UNC Chapel Hill 2 UNC Coastal Studies Institute

National Park Service photohttp://www.nps.gov/caha/views.htm

Site Locations

Synopsis

• System Changes– Variations in Coverage– Antenna Pattern Measurement– Radio Frequency Noise

• ADCP Comparison• Gulf Stream Position & Shelf Break

Currents

Hatteras Radials and Events

4.80 4.47 4.55

Duck Radials and Events

4.80 4.474.55 4.53

Daily Medians

Hurricane Isabel

Percent Coverage

Percent Coverage

Strange Vectors

Antenna Pattern Measurement

Antenna Pattern Measurement

Duck Patterns

2004/12/06

2003/12/122003/06/26

2004/12/06

Antenna Pattern Measurement

HatterasPatterns

2003/06/24 2004/05/25

2004/06/08

Noise in the Spectral Data

2004/12/12

00:00 18:00

Radio Frequency Noise2004/12/12

Duck Tx

00:00 18:00

Noise in the Spectral Data2003/12/03

Duck

Hatteras

02:00 08:00 14:00

Radio Frequency Noise2003/12/03

02:00 08:00 14:00

ADCP Mooring Location

ADCPLocation

ADCP ComparisonMeasured Beam Patterns

ADCP ComparisonIdeal Beam Patterns

Hovmoller Line

HovmollerLine: 35.5

Hovmoller Northward Velocity Diagram2004/08

Hovmoller Northward Velocity Diagram2004/11

Summary

• Coverage varies significantly• Many factors may influence data quality:

– Radio Frequency noise – Antenna Pattern Measurements– Antenna position and transmit frequency

• ADCP Comparison shows mediocre results

• APMs effect the data but quality may be similar

• Gulf Stream Front effects shelf currents

Future Work

• Compare Codar radials to ADCP’s directional components

• Frequency decomposition of both datasets

• Develop better outlier identification procedures

• Compare with ship-track ADCP from Gawarkiwecz and Savidge cruise (Fall 2004)

• Look at quantification of the Gulf Stream Front and its effects on shelf flow

Thanks

• Harvey Seim (Ideas, Money)• Mike Muglia (Ideas, Upkeep)• CodarOS (Great support)• ROWG (Sharing of Ideas)• SEACOOS (Funding, Ideas)• You all for listening and sharing

expertise!