Local and non-local curvature approximation: a new asymptotic theory for wave scattering

Elfouhaily, Tanos; Guignard, Stephan; Awadallah, R.S.; Thompson, D. R.

doi:10.1088/0959-7174/13/4/308

Cited by 70 publications

(60 citation statements)

References 15 publications

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“…[13] On the basis of Elfouhaily et al [2003bElfouhaily et al [ , 2003a developments, the scattering matrix expansion up to the first order is…”

Section: Local and Resonant Curvature Approximationsmentioning

confidence: 99%

“…B is the Bragg kernel and K is the Kirchhoff kernel (see, e.g., Elfouhaily et al [2003a] for their analytical expression). In equation (7), the second term represents a firstorder correction to Kirchhoff solution given by the first term to take into account the surface curvature effects on the polarization state of the scattered field.…”

Section: Local and Resonant Curvature Approximationsmentioning

confidence: 99%

“…[4] To go beyond the TSM's formalism with the arbitrary choice to separate large modulating and small modulated waves, Elfouhaily et al [2003a] proposed an asymptotic theory based on Kirchhoff Approximation (KA) taking into account the curvature effect of the surface on the polarization state of the scattered field. On the basis of both analytical comparisons with TSM and data comparisons, the proposed solution, termed LCA-1, exhibits polarization sensitivity very close to TSM [Mouche et al, 2007a].…”

Section: Introductionmentioning

confidence: 99%

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Importance of the sea surface curvature to interpret the normalized radar cross section

et al. 2007

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[1] Asymptotic models (small perturbation and small slope approximation at first-order, Kirchhoff approximation or two-scale model) used to predict the normalized radar cross section of the sea surface generally fail to reproduce in detail backscatter radar measurements. In particular, the predicted polarization ratio versus incidence and azimuth angles is not in agreement with experimental data. This denotes the inability of these standard models to fully take into account the roughness properties with respect to the sensor's configuration of measurement (frequency, incidence, and polarization). On the basis of particular assumptions, to decompose the scattered electromagnetic field between zones covered with freely propagating waves and others where roughness and slopes are enhanced, recent works were able to match observations. In this paper, we do not assume such a decomposition but study the latest improvements obtained in the field of approximate scattering theories of random rough surfaces using the local and resonant curvature approximations. These models are based on an extension of the Kirchhoff Approximation up to first order to relate explicitly the curvature properties of the sea surface to the polarization strength of the scattered electromagnetic field. Consistency with previous approaches is discussed. As shown, dynamically taking into account the sea surface curvature properties of the surface is crucial to better interpret normalized radar cross-section and polarization ratio sensitivities to both sensor characteristics and geophysical environment conditions. The proposed developments, termed the Resonant Curvature Approximation (RCA), are found to reproduce experimental data versus incidence angle and azimuth direction. The polarization sensitivity to the wind direction and incidence angle is largely improved. Finally, Gaussian statistical assumption adopted to derive the analytical expression of the normalized radar cross section is also discussed. In particular, the third-order cumulant function is shown to better reproduce the second-order up-/down-wind azimuth modulation. The proposed developments appear very promising for improvement of our understanding and analysis of both sea surface radar backscatter and Doppler signals.Citation: Mouche, A. A., B. Chapron, N. Reul, D. Hauser, and Y. Quilfen (2007), Importance of the sea surface curvature to interpret the normalized radar cross section,

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“…[13] On the basis of Elfouhaily et al [2003bElfouhaily et al [ , 2003a developments, the scattering matrix expansion up to the first order is…”

Section: Local and Resonant Curvature Approximationsmentioning

confidence: 99%

Section: Local and Resonant Curvature Approximationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Importance of the sea surface curvature to interpret the normalized radar cross section

et al. 2007

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“…The semiempirical spectrum model by Kudryavtsev et al [37] provides a physically consistent statistical description at decimetric waves (major surface emitters at L-band), and when used jointly with the SSA model, it seems to provide accurate emissivity predictions, a conclusion that requires further experimental verification. A new asymptotic scattering theory, which accounts for surface curvature, has been developed recently by Elfouhaily et al [44]. This curvature formulation unifies the electromagnetic models and explains polarization sensitivity to roughness.…”

Section: B L-band Sea Surface Emissivity Forward Modelsmentioning

confidence: 99%

The determination of surface salinity with the European SMOS space mission

Font

Lagerloef

Vine

et al. 2004

IEEE Trans. Geosci. Remote Sensing

148

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Abstract-The European Space Agency Soil Moisture and Ocean Salinity (SMOS) mission aims at obtaining global maps of soil moisture and sea surface salinity from space for large-scale and climatic studies. It uses an L-band (1400-1427 MHz) Microwave Interferometric Radiometer by Aperture Synthesis to measure brightness temperature of the earth's surface at horizontal and vertical polarizations ( h and v ). These two parameters will be used together to retrieve the geophysical parameters. The retrieval of salinity is a complex process that requires the knowledge of other environmental information and an accurate processing of the radiometer measurements. Here, we present recent results obtained from several studies and field experiments that were part of the SMOS mission, and highlight the issues still to be solved.

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“…-Small Slopes Approximation (SSA) is based on a perturbative expansion with respect to a slope parameter, and imposes corresponding constraints on the surface [3] . -Weighed Curvature Approximation (WCA) naturally extends any tangent plan approximation to take into account curvature corrections [4] . -The Integral Equation Method (IEM) provides an iterative solution of the pair of integral equations for the tangential components of the electric and magnetic fields at the dielectric interface [5] .…”

Section: A Asymptotic Scattering Modelsmentioning

confidence: 99%

On the use of rigorous microwave interaction models to support remote sensing of natural surfaces

Reul

Guérin

Soriano

et al.

Proceedings. 2005 IEEE International Geoscience and Remote Sensing Symposium, 2005. IGARSS '05.

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Local and non-local curvature approximation: a new asymptotic theory for wave scattering

Cited by 70 publications

References 15 publications

Importance of the sea surface curvature to interpret the normalized radar cross section

Importance of the sea surface curvature to interpret the normalized radar cross section

The determination of surface salinity with the European SMOS space mission

On the use of rigorous microwave interaction models to support remote sensing of natural surfaces

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