Development of HF ocean radar in japan

The HF ocean radar was developed in Japan from 1987 by Okinawa Radio Observatory, Communications Research Laboratory. We measured ocean surface currents and developed the method to estimate wave spectra. The observations of ocean surface currents were conducted in various areas. The observation in the east of Okinawa, where mesoscale eddies are dominant, is presented. We can observe the convergent zone associated with the front of a mesoscale eddy. Furthermore, the short-wave directions and spread parameters were estimated from first-order scattering. We also developed the method to estimate ocean wave spectra from Doppler spectra. We extended the theory of HF radio wave scattering from the sea surface. It is possible to explain the underestimation of waveheights, which was previously pointed out.