An exact analytic representation of a regular or interferometric SAR image of ocean swell

Gregory Zilman*, Lev Shemer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The problem of obtaining quantitative data on spatial ocean wave spectra from the images of the ocean surface by either regular SAR or along-track interferometric SAR (INSAR) is studied. The dominant mechanism which allows imaging of ocean waves by SAR/INSAR is the so-called velocity bunching. This mechanism is essentially nonlinear. The theoretical analysis of SAR/INSAR imagery of the ocean surface due to velocity bunching is performed and nonlinear solutions of the SAR/INSAR images of monochromatic waves and of the spectra of these images are obtained. Analytic expressions are presented here which allow to simulate accurately both SAR and INSAR images of waves with arbitrary lengths heights and propagation directions. It is demonstrated that a monochromatic wave expands in the SAR/INSAR images into an infinite number of harmonics. In addition to the nonlinearity parameters of SAR which is related to the velocity bunching mechanism it is shown that for complex INSAR the degree of nonlinearity depends also on separation time between the two antennas. The results of the present study indicate that in addition to the prevailing practice to consider the phase component of the INSAR image an analysis of the imaginary part of the complex INSAR map of the ocean surface may provide some supplementary information beneficial in particular for rough sea.

Original languageEnglish
Pages (from-to)1015-1022
Number of pages8
JournalIEEE Transactions on Geoscience and Remote Sensing
Issue number2 II
StatePublished - 1999


FundersFunder number
Department of Fluid Mechanics and Heat Transfer
Tel-Aviv UniversityTel-Aviv 69978
Israel Science Foundation253/96-3


    • Ocean waves
    • Remote sensing
    • Sar/along track interferometric sar image
    • Sea surface


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