Surface Currents off the Outer Banks of North Carolina Luke Stearns, UNC Chapel Hill

Site Installation Duck and Buxton sites installed Summer 2003 Transponder calibrations occurred that summer also Both sites “operational-ish” since then

Theoretical Coverage Overlap region leaves large areas of radial coverage unused NOAA plans to make long range Codar at Cape Henry operational soon Cape Henry Duck Buxton

Percent Coverage: Measured Patterns December 2003 What Happens to the signal in these radial directions? Why is there less coverage?

Site Configuration Aerial photographs provided by North Carolina Department of Environment and Natural Resources. images.enr.state.nc.us DuckBuxton Could the pier be causing some of this interference? Could the distance behind the dunes cause losses?

Obstacles at Duck Large metal tower Steel and concrete pier

Obstacles at Buxton Metal fence Extensive sewage pipes and the treatment shed The dune

Objectives Optimize beam patterns Compare with other observations Evaluate system performance Provide information to local community and partner institutions or organizations

Ideal Beam Patterns Coverage for locations reporting data at least 40% of the time is shown Places where we don’t expect coverage (like land) don’t show up much at all Totals look fairly reasonable in most areas Extent is fairly good, but buxton is bad to the north (where the overlap is with duck)

Ideal Beam Patterns

Measured Beam Patterns

Duck Radials have slightly increased coverage Buxton radials have increased coverage in some areas worse in others The first and last direction bins look to be contaminated Overall extent of totals is reduced The divergence pattern at the Southern limit of coverage is more reasonable

Objectives Optimize beam patterns Compare with other observations Evaluate system performance Provide information to local community and partner institutions or organizations

Codar M2 Tides 60% Coverage criteria used Tides computed with t_tide package for matlab

M2 Tidal Comparison Orientation and ellipticity agree reasonably well with ADCIRC and Lentz et. al. observations Codar Magnitude smallest (surface), largest for ADCIRC (depth average), in between for Lentz (near surface) Lentz et. al (Barotropic Tides on the North Carolina Shelf )

The amplitudes of the M2 tidal component are different for Adcirc, Codar, and Lentz et. al. WHY? How different are they? What does this tell us about data quality? M2 Tidal Amplitude Ratio (ADCIRC/Codar) MajorMinor Only in a few locations do they agree on Major amplitude. Almost everywhere else ADCIRC amplitudes are larger The structure seems much noisier in Minor amplitudes.

SST and Codar (Snapshot 1) Captures the Gulf Stream front well Seems to show currents turning spatially where the cool filament turns Passes the “Looks Good” test AVHRR Satellite SST data from

SST and Codar (Snapshot 2) Shows reasonable along isobath flow Shows Southward jet slamming into the Gulf Stream Convergence looks huge, and SST Gulf Stream front no longer consistent with Codar observations

Objectives Optimize beam patterns Compare with other observations Evaluate system performance Provide information to local community and partner institutions or organizations

Monthly Mean Currents (Measured, 40% coverage) Southward, along isobath flow 5 month mean

Offshore transport Increasing offshore veering of MAB Southward jet Consistent with Gawarkiewicz and Lozier

Gulf Stream Gulf Stream shows up in all images Gulf Stream fairly consistent

Gulf Stream decrease Gulf Stream shows up in all images Gulf Stream apparent but weak

Objectives Optimize beam patterns Compare with other observations Evaluate system performance Provide information to local community and partner institutions or organizations

Providing Information Products: Data Plots Provide Data plots for laymen, technicians, and scientists

Providing Information Products: Radial Currents Radials provide a good diagnostic tool for technicians and scientists

Providing Information Products: Data Access DODS access provides real-time data to scientific users Real Time access provides skill assessment for modeling community

What Next? Get direct data comparison to provide more confidence in the data ADCP comparison is soon to come Drifter track comparison likely for summer to fall Work towards actively distributing information products Expand the network of HF Radars!

Thanks!!! Codar Ocean Sensors (outstanding support!) Josh Kohut, Scott Glenn and the Rutgers Crew Mike Muglia for keeping everything alive, processing and many good ideas Harvey Seim for guidance, direction, hard work, and the master plan! SEACOOS (Observing and Data Management) Nick Shay and Tom Cook (the SEACOOS HF Radar experts) John Bane, Sara Haines, Brian Blanton, Catherine Edwards, Karen Edwards for ideas and support Glen Gawarkiewicz for MAB expertise Friends and Family for support and patience!