Coastal Ocean Dynamics Radar (CODAR): NOAA's Surface Current Mapping System

NOAA has developed a shore-based HF radar system that maps ocean surface currents out to 60 km from shore. Currents are derived from the Doppler shift of radar echoes from 6-m ocean waves, whose phase speed is altered by underlying currents. A map containing 800 current vectors covering 2000 square kilometers of ocean can be produced automatically in 45 minutes by a compact, transportable package that can be set up in about two hours. The CODAR system has been tested in measurements of the Gulf Stream off the Florida coast, tidal oscillations in Alaska's Cook Inlet and Puget Sound, and the complex outflow from the Savannah River off the Georgia coast. Comparison with surface drifters and a system error analysis indicate that CODAR measures surface currents with at least 10 cm/s accuracy.