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On the theory of electromagnetic waves scattering from the sea surface at low grazing angles
Author(s) -
Voronovich A. G.
Publication year - 1996
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/96rs02250
Subject(s) - scattering , curvature , surface (topology) , wavelength , diffraction , tangent , physics , plane (geometry) , electromagnetic radiation , optics , range (aeronautics) , scale (ratio) , plane wave , born approximation , geometry , computational physics , mathematics , materials science , quantum mechanics , composite material
Scattering of electromagnetic (EM) waves from the sea surface is usually considered with the help of a two‐scale (composite surface) model. It is shown theoretically that for broad wavelength range at grazing angles less than about 20°, diffraction of the incident field on large‐scale (undulating) components cannot be considered using the tangent plane (Kirchhoff) approximation. In other words, an undulating surface cannot be treated as a set of locally plane facets, and its curvature becomes an important parameter. The effects of curvature of the undulating surface are estimated for a two‐dimensional situation. It is shown that in this case, backscattering cross sections at low grazing angles are proportional to the sin 2 α rather than to the sin 4 α (which would be the case according to Rice's classical formulae). This corresponds to experimental results. The theoretical curve of the σ HH /σ VV ratio fits well the experimental data published by Lee et al. [1995] (for “slow” signals).