Tests of remote skywave measurement of ocean surface conditions

A pulse-Doppler backscatter radar operating in the HF band was used to test the feasibility to measure ocean surface motions in the North Atlantic Ocean under a variety of environmental conditions. Using the ionosphere as a part of the propagation path, data were collected at ranges from 600 to 2200 nmi. Environmental conditions included a relatively small hurricane, a large storm, and a relatively calm ocean. The Doppler data were converted to wind vectors and compared with weather data taken at the same times and places. Preliminary results indicate that there is, in general, good agreement between wind directions as determined from the radar data and this is indicated on the weather chart at all ranges and under all of the environmental conditions encountered. The agreement in wind strengths is fair to good, but at present reliability is mainly limited to the first-hop data because of multiple propagation modes. Improvements in this technique can be expected from refinement in the theoretical models of scattering, and in developing radar operation methods that minimize multipath responses.