Measurements of upper-ocean surface currents with high-frequency radar

High-frequency (HF) radar measurements of ocean surface currents offer a convenient means of measuring not only the surface current, but its vertical shear within the uppermost two meters of the ocean. HF radar measurements made off the central California coast reveal a clockwise rotation of the current vector as a function of increasing depth even within the uppermost meter of water. Comparisons of radial HF radar derived currents to the radial components of ship-mounted acoustic Doppler current profiler measurements of currents at the 9-13 meter depth bin show good correlation, but an offset of about 13 cm/s. Many features of the ocean circulation at the boundary layer near the air-sea interface remain to be explored and multi-frequency, HF radar offers a powerful means of accomplishing this task.