Progress in the interpretation of HF sea echo: HF radar as a remote sensing tool

When HF radar systems are used for surveillance or tracking of ships or aircraft the strong signal from the ocean surface is termed clutter since it obscures the required signals. Clutter characteristics are related to the ocean ware spectrum leading to HF radar being used for remote sensing. The author describes work on the inversion of the Doppler spectrum of HF radar echoes from the ocean surface to provide measurements of the ocean wave directional spectrum