Remote sensing of ocean waves by along‐track interferometric synthetic aperture radar

A new wave retrieval method for the Along-Track Interferometric Synthetic Aperture Radar (AT-InSAR) phase image is presented. The new algorithm, named parametric retrieval algorithm (PRA), uses the full nonlinear mapping relations. It differs from previous retrieval algorithms in that it does not require a priori information about the sea state or the wind vector from scatterometer data. Instead, it combines the observed AT-InSAR phase spectrum and assumed wind vector to estimate the wind sea spectrum. The method has been validated using several C-band and X-band HH-polarized AT-InSAR observations collocated with spectral buoy measurements. In this paper, X-band and C-band HH-polarized AT-InSAR phase images of ocean waves are first used to study AT-InSAR wave imaging fidelity. The resulting phase spectra are quantitatively compared with forward-mapped in situ directional wave spectra collocated with the AT-InSAR observations. Subsequently, we combine the parametric retrieval algorithm (PRA) with X-band and C-band HH-polarized AT-InSAR phase images to retrieve ocean wave spectra. The results show that the ocean wavelengths, wave directions, and significant wave heights estimated from the retrieved ocean wave spectra are in agreement with the buoy measurements.

[1]  Harald E. Krogstad,et al.  A Simple Derivation of Hasselmann's Nonlinear Ocean-Synthetic Aperture Radar Transform , 1992 .

[2]  Werner Alpers,et al.  Estimation of the ocean wave–radar modulation transfer function from synthetic aperture radar imagery , 1994 .

[3]  K. Hasselmann,et al.  On the nonlinear mapping of an ocean wave spectrum into a synthetic aperture radar image spectrum and its inversion , 1991 .

[4]  C. Mastenbroek,et al.  A semiparametric algorithm to retrieve ocean wave spectra from synthetic aperture radar , 2000 .

[5]  Werner Alpers,et al.  Measurement of the ocean wave-radar modulation transfer function at 35 GHz from a sea-based platform in the North Sea , 1986 .

[6]  R. Raney,et al.  Theory of synthetic aperture radar ocean imaging: A MARSEN view , 1985 .

[7]  Eliezer Kit,et al.  Simulation of an interferometric synthetic aperture radar imagery of an ocean system consisting of a current and a monochromatic wave , 1991 .

[8]  Harald Johnsen,et al.  SAR-ocean wave inversion using image cross spectra , 1995, IEEE Trans. Geosci. Remote. Sens..

[9]  R. Goldstein,et al.  Interferometric radar measurement of ocean surface currents , 1987, Nature.

[10]  Werner Alpers,et al.  On the nonlinear integral transform of an ocean wave spectrum into an along-track interferometric synthetic aperture radar image spectrum , 2003 .

[11]  P. Heimbach,et al.  An improved algorithm for the retrieval of ocean wave spectra from synthetic aperture radar image spectra , 1996 .

[12]  Richard E. Carande,et al.  Estimating ocean coherence time using dual-baseline interferometric synthetic aperture radar , 1994, IEEE Trans. Geosci. Remote. Sens..

[13]  M. Gade,et al.  Investigation of multifrequency/multipolarization radar signatures of rain cells over the ocean using SIR‐C/X‐SAR data , 1998 .

[14]  L. Shemer,et al.  Estimates of currents in the nearshore ocean region using interferometric Synthetic Aperture Radar , 1993 .

[15]  M. Donelan,et al.  Directional spectra of wind-generated ocean waves , 1985, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[16]  T. Barnett,et al.  Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP) , 1973 .

[17]  Paris W. Vachon,et al.  Validation of along-track interferometric SAR measurements of ocean surface waves , 1999, IEEE Trans. Geosci. Remote. Sens..

[18]  Jochen Horstmann,et al.  Sea surface imaging with an across-track interferometric synthetic aperture radar: the SINEWAVE experiment , 2001, IEEE Trans. Geosci. Remote. Sens..

[19]  S. Lehner,et al.  An empirical approach for the retrieval of integral ocean wave parameters from synthetic aperture radar data , 2007 .

[20]  Werner Alpers,et al.  Simulation of ocean waves imaging by an along-track interferometric synthetic aperture radar , 1997, IEEE Trans. Geosci. Remote. Sens..

[21]  Werner Alpers,et al.  A new nonlinear integral transform relating ocean wave spectra to phase image spectra of an along-track interferometric synthetic aperture radar , 1999, IEEE Trans. Geosci. Remote. Sens..

[22]  D. Ross,et al.  On the detectability of ocean surface waves by real and synthetic aperture radar , 1981 .

[23]  R. Romeiser.  Current measurements by airborne along-track InSAR: measuring technique and experimental results , 2005, IEEE Journal of Oceanic Engineering.