On the Relative Importance of Motion-Related Contributions to the SAR Imaging Mechanism of Ocean Surface Waves

Alpers, Werner; Bruening, Claus

doi:10.1109/tgrs.1986.289702

Cited by 185 publications

(75 citation statements)

References 27 publications

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“…Typical expressions for azimuth resolution have the form [12], [13] (4) where integration time; platform velocity; coherence time; surface acceleration. The first term is the theoretical SAR resolution for stationary coherent targets where the maximum available integration time is dictated by the antenna beamwidth, the range, and the platform velocity.…”

Section: A Ocean Surface Coherence Propertiesmentioning

confidence: 99%

“…Given the estimated radial velocities from the forward and aft beams, the along-track and cross-track components of the horizontal surface velocity are obtained using simple geometry (11) where the plus and minus superscripts correspond to forward and aft beams, respectively. The variances of these current estimates are (12) and the total velocity variance is the sum of these, which can be related to the measured phase uncertainty using (8), yielding (13)…”

Section: Dbi Point Source Responsementioning

confidence: 99%

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Dual-beam interferometry for ocean surface current vector mapping

Frasier

Camps

2001

IEEE Trans. Geosci. Remote Sensing

148

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Abstract-The recent use of along-track interferometry (ATI) in synthetic aperture radar (SAR) has shown promise for synoptic measurement of ocean surface currents. ATI-SARs have been used to estimate wave fields, currents, and current features. This paper describes and analyzes a dual-beam along-track interferometer to provide spatially resolved vector surface velocity estimates with a single pass of an aircraft. The design employs a pair of interferometer beams, one squinted forward and one squinted aft. Each interferometric phase is sensitive to the component of surface Doppler velocity in the direction of the beam. Therefore, a proper combination of these measurements provides a vector surface velocity estimate in one pass of the aircraft. We find that precise measurements dictate widely spaced beams and that the spatial resolution for the squinted SAR is essentially identical to the sidelooking case. Practical instrument design issues are discussed, and an airborne system currently in development is described. Through computer simulation, we observe the azimuthal displacement of interferometric phases by moving surfaces identical to those of conventional SAR and find that such displacement can bias the estimated surface velocity.

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Section: A Ocean Surface Coherence Propertiesmentioning

confidence: 99%

Section: Dbi Point Source Responsementioning

confidence: 99%

Dual-beam interferometry for ocean surface current vector mapping

Frasier

Camps

2001

IEEE Trans. Geosci. Remote Sensing

148

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“…Longer the wavelength of ocean waves is, longer the coherence time becomes. For AT-InSAR operating at X-to L-bands, the coherence time is estimated as approximately 0.2-0.02 ms [65,66,[696][697][698][699].…”

Section: Along-track Insarmentioning

confidence: 99%

Recent Trend and Advance of Synthetic Aperture Radar with Selected Topics

2013

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The present article is an introductory paper in this special issue on synthetic aperture radar (SAR). A short review is presented on the recent trend and development of SAR and related techniques with selected topics, including the fields of applications, specifications of airborne and spaceborne SARs, and information contents in and interpretations of amplitude data, interferometric SAR (InSAR) data, and polarimetric SAR (PolSAR) data. The review is by no means extensive, and as such only brief summaries of of each selected topics and key references are provided. For further details, the readers are recommended to read the literature given in the references theirin.

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“…Traditionally, the methodology of wave spectra retrieval needs a good understanding of complicated SAR wave imaging mechanisms typically explained by the two-scale model, including the tilt and hydrodynamic modulations [2] on sea surface short waves. However, there is a specific non-linear distortion of SAR wave imaging, named velocity bunching [3], due to the relative motion of the sea surface waves to a satellite platform, that leads to waves shorter than a specific wavelength not detectable by SAR [4,5].…”

Section: Introductionmentioning

confidence: 99%

Ocean Wave Parameters Retrieval from Sentinel-1 SAR Imagery

Shao

Zhang

et al. 2016

Remote Sensing

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Abstract:In this paper, a semi-empirical algorithm for significant wave height (H s ) and mean wave period (T mw ) retrieval from C-band VV-polarization Sentinel-1 synthetic aperture radar (SAR) imagery is presented. We develop a semi-empirical function for H s retrieval, which describes the relation between H s and cutoff wavelength, radar incidence angle, and wave propagation direction relative to radar look direction. Additionally, T mw can be also calculated through H s and cutoff wavelength by using another empirical function. We collected 106 C-band stripmap mode Sentinel-1 SAR images in VV-polarization and wave measurements from in situ buoys. There are a total of 150 matchup points. We used 93 matchups to tune the coefficients of the semi-empirical algorithm and the rest 57 matchups for validation. The comparison shows a 0.69 m root mean square error (RMSE) of H s with a 18.6% of scatter index (SI) and 1.98 s RMSE of T mw with a 24.8% of SI. Results indicate that the algorithm is suitable for wave parameters retrieval from Sentinel-1 SAR data.

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On the Relative Importance of Motion-Related Contributions to the SAR Imaging Mechanism of Ocean Surface Waves

Cited by 185 publications

References 27 publications

Dual-beam interferometry for ocean surface current vector mapping

Dual-beam interferometry for ocean surface current vector mapping

Recent Trend and Advance of Synthetic Aperture Radar with Selected Topics

Ocean Wave Parameters Retrieval from Sentinel-1 SAR Imagery

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