High Frequency (HF) Radar is used by ocean researchers to measure surface current velocity fields over the coastal ocean. An HF-radar system can measure surface currents with a spatial resolution of 1-6 km with a maximum range of 200 km. The higher spatial resolution, the lower the range. Currents are acquired every hour. All the HF-Radars used in the Mid-Atlantic are the SeaSonde manufactured by Codar Ocean Sensors.

The HF-Radars, like police radars, measure the speed of something moving toward or away from them. Instead of cars, HF-Radars measure the speed of the ocean surface. With two antennas, scientists can determine the speed and direction (N, S, E, W) of currents in multiple areas, and generate maps of the ocean surface using arrows to show the current direction.