In the following sections, we attempt to respond to the charges listed 

 in the introduction, and consider the operational and research needs in 

 various oceanographic subject areas in which the use of Synthetic Aperture 

 Radar might have a significant impact. 



A. SURFACE WAVES 



There is an operational need for 2-dimensional wave spectra in deep 

 water both for purposes of wave forecasting and for the verification and 

 refinement of wave models used in wave forecasting. The accumulation of 

 observations of this kind is necessary for a better definition of the 

 climatology of waves. For deep-water wave spectra, a 15°-angular resolution 

 is desirable together with a 0.5-m accuracy in significant wave height over 

 the range 1-20 m. A 20 percent accuracy in spectral density is desired over 

 about 15 frequency bands between 0.05 to 0.3 Hz with a resolution better than 

 0.01 Hz near the spectral peak. Information should be at grid scales of 100 

 km in major ocean basins with the capability of going to 10 km over small 

 regions; an ideal coverage would be every three hours. 



In shallow water (depth less than 100), there is again a need for 2- 

 dimensional wave spectra for the verification and refinement of wave models 

 for coastal wave forecasting and to establish the climatology of waves, the 

 influence of wave-current interactions, and the spatial variability of wave 

 and currents. The requirements for shallow water spectra are rather tighter — 

 an angular resolution of 5°, a 0.25-m significant wave height accuracy in the 

 1-20-m range and a grid scale that could be as small as 1 km. Other 

 specifications are the same as for deep water. 



There are also significant research needs for wave data. There is 

 presently considerable interest in the spatial distribution of wave 

 "groupiness," and well-defined spectra are needed for spatial evolution 

 studies. Observational information is needed on wave-current interactions and 

 on the characteristics and distribution of breaking waves. In shallow water, 

 data are needed on wave-bottom interactions, including refraction, 

 attenuation, and breaking, as well as on wave-current interactions in shallow 

 water. For research purposes, the data are needed with the maximum possible 

 accuracy attainable. 



In this area, the present capabilities of SAR include the measurement of 

 wave length and direction, particularly of swell, and the characteristics of 

 swell propagation from storms and refraction in shallow water. SAR can 

 resolve wave lengths and directions in complex wave fields as in hurricanes. 

 Potential capabilities include the measurement of significant wave height, the 

 directional wave distribution, the spectra in shallow water, and the 

 determination of wind speed and direction. SAR also has useful potential in 

 the measurement of wave fields in severe storms. 



4-2 



