. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography (c) WAVELENGTH = 60 m ANGLE = 83' WAVELENGTH = 150 m ANGLE = -15"; 60m u± Fig. 4. (a) band synthetic aperture radar image of 60-m and 150-m ocean waves off Alaska; (b) two-dimensional Fourier transform of part o showing wave energy con- centrations as bright spots; (c) interpretation of part b in terms of two dominant wave trains, with densitometer traces of the figure taken at 83° and -15° (Jet Propulsion Laboratory). sional power spectral den
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography (c) WAVELENGTH = 60 m ANGLE = 83' WAVELENGTH = 150 m ANGLE = -15"; 60m u± Fig. 4. (a) band synthetic aperture radar image of 60-m and 150-m ocean waves off Alaska; (b) two-dimensional Fourier transform of part o showing wave energy con- centrations as bright spots; (c) interpretation of part b in terms of two dominant wave trains, with densitometer traces of the figure taken at 83° and -15° (Jet Propulsion Laboratory). sional power spectral density as a function of surface wave vector. A reasonably complete determination of this function near storms, when used as input data to numerical models, would allow wave forecasts to be made at a distance of several hundred kilometers from the high wind regions. Where the field is nonhomogeneous , as near shorelines, near intense low pressure systems, or in shoaling water, an image of the surface field is more appropriate than a spectrum. Significant wave height. For the estimated capability, it appears possible to measure significant wave height W1/3 with a precision of ±1 m or ±25% of the actual height over a range of 1-20 m along the subsatellite track on a near-all- weather basis by using the short- pulse altimeter I Walsh, 19741. Figure 3 illustrates the effect of a rough ocean in broadening a 3-ns radar altimeter pulse, the measure- ment of which forms the basis for the determination of W1/3. Surface wave spectrum. For the surface wave power spectrum the synthetic aperture radar (SAR) may yield square amplitude measure- ments consistent with the precision for //1/3 (above) for all wavelengths between 50 m and the largest obser- vable length, measured at 10° inter- vals for all angles of propagation; the spatial and temporal resolution is limited to small samples taken near the United States or to more intensive spectra in selected regions. The instrument appears to
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