On the Doppler spectra obtained by HF ocean surface radars, there are two strong peaks called the first-order echoes which are due to the Bragg resonance between radar wave and ocean surface waves. The shape of the first-order echoes sometimes shows large broadening as over 100cm/s. The effects of the ocean surface current field on the shape of the first-order echo are investigated by the numerical simulation of the radial current velocity spectra. The front like features make the radial current velocity spectra broadening, the degree of broadening depends not only on the property of the features but also on the direction of observation. The eddy like features of the surface current field also make the spectra broadening and the degree of broadening depends only on the property of the features. THe simulated spectra of radial current velocity, however, do not show the splitting under various conditions, as observed several times.
展开▼
