Bistatic observations of the ocean surface with HF radar, satellite and airborne receivers

A new concept has been developed which can view vast regions of the Earth's surface. Ground HF transmissions are reflected by the ionosphere to illuminate the ocean over a few thousand kilometers. HF receivers detect the radio waves scattered by the sea and land surface. Using the theory of radio wave scatter from ocean surfaces, the HF data is then processed to yield the directional wave-height spectrum of the ocean. This technique has several advantages over existing remote sensing methods. A large area of the ocean can be sampled to yield the wave-height characteristics with high, km-scale resolution. The wave height spectrum can be directly compared with temporal frequency spectrum obtained with buoys at specific points in the ocean volume. Furthermore, the technique uses HF waves which penetrate the dense rain found in hurricanes.