An Analysis of short pulse and dual frequency radar techniques for measuring ocean wave spectra from satellites

A four-frequency moment characterization of backscatter from the near-vertical is applied to an analysis of the short pulse (SP) and dual frequency (DF) microwave techniques. It is found that (1) the range reflectivity modulation spectrum closely approximates the directional wave slope spectrum. Harmonic distortion is small and is a minimum near 10° incidence. (2) The SP measurement SNR (signal-to-noise ratio) is typically 20–30 dB greater than the narrowband DF SNR. The difference in SNR is the ratio of the range beam extent to pulse length, minus the ratio of beam-limited to pulse-limited Doppler spreads. It is concluded that narrowband DF measurements are basically impractical. To be practical, the DF technique must be ‘widebanded.’ SP measurements on the other hand are found to be practical, using existing space-qualified microwave hardware.

[1]  D. E. Barrick,et al.  Relationship between slope probability density function and the physical optics integral in rough surface scattering , 1968 .

[2]  W. L. Jones,et al.  Aircraft measurements of the microwave scattering signature of the ocean , 1977 .

[3]  G. Brown,et al.  Backscattering from a Gaussian-distributed perfectly conducting rough surface , 1978 .

[4]  Estimation of the sea surface's two-scale backscatter parameters , 1978 .

[5]  T. Teichmann,et al.  The Measurement of Power Spectra , 1960 .

[6]  ANALYSIS OF A GENERAL SYSTEM FOR THE DETECTION OF AMPLITUDE MODULATED NOISE , 1956 .

[7]  I. Miller.  Probability, Random Variables, and Stochastic Processes , 1966 .

[8]  W. Munk,et al.  Measurement of the Roughness of the Sea Surface from Photographs of the Sun’s Glitter , 1954 .

[9]  E. David,et al.  Two Frequency Radar Interferometry Applied to the Measurement of Ocean Wave Height , 1973 .

[10]  T. T. Wilheit,et al.  The effect of wind on the microwave emission from the ocean's surface at 37 GHz , 1979 .

[11]  G. Valenzuela.  Theories for the interaction of electromagnetic and oceanic waves — A review , 1978 .

[12]  Bistatic radar sea state monitoring , 1972 .

[13]  M. S. Longuet-Higgins.  The distribution of the sizes of images reflected in a random surface , 1959 .

[14]  William J. Plant,et al.  Ocean wave‐radar modulation transfer functions from the West Coast Experiment , 1980 .

[15]  J. Wright,et al.  Modulation of short gravity‐capillary waves by longer‐scale periodic flows—A higher‐order theory , 1979 .

[16]  W. Townsend,et al.  An initial assessment of the performance achieved by the Seasat-1 radar altimeter , 1980, IEEE Journal of Oceanic Engineering.

[17]  K. Tomiyasu.  Short Pulse Wide-Band Scatterometer Ocean Surface Signature , 1971 .

[18]  R. J. Wagner,et al.  Rough‐Surface Scattering: Shadowing, Multiple Scatter, and Energy Conservation , 1970 .

[19]  Frederick C. Jackson,et al.  The reflection of impulses from a nonlinear random sea , 1979 .

[20]  K. Hasselmann,et al.  The two-frequency microwave technique for measuring ocean-wave spectra from an airplane or satellite , 1978 .

[21]  M. Longuet-Higgins.  The effect of non-linearities on statistical distributions in the theory of sea waves , 1963, Journal of Fluid Mechanics.

[22]  William J. Plant.  Studies of backscattered sea return with a CW, dual-frequency, X -band radar , 1977 .

[23]  D. Schuler,et al.  Remote sensing of the sea surface using one‐ and two‐frequency microwave techniques , 1980 .

[24]  D. Barrick,et al.  Wind dependence of quasi-specular microwave sea scatter , 1974 .