The GO4 Model in Near-Nadir Microwave Scattering From the Sea Surface

Type Article
Date 2015-11
Language English
Author(s) Boisot Olivier1, 2, Nouguier FredericORCID1, Chapron BertrandORCID3, Guerin Charles-Antoine1
Affiliation(s) 1 : Aix Marseille Univ, Univ Toulon, CNRS, MIO,IRD,UM 110, F-83957 La Garde, France.
2 : Ctr Natl Etud Spatiales, Collecte Localisat Satellites, F-31400 Toulouse, France.
3 : IFREMER, Lab Oceanog Spatiale, F-29280 Plouzane, France.
Source Ieee Transactions On Geoscience And Remote Sensing (0196-2892) (Ieee-inst Electrical Electronics Engineers Inc), 2015-11 , Vol. 53 , N. 11 , P. 5889-5900
DOI 10.1109/TGRS.2015.2424714
WOS© Times Cited 18
Keyword(s) Curvature, geometrical optics, near-nadir, ocean radar sensing, slope
Abstract We introduce a practical and accurate model, referred to as "GO4," to describe near-nadir microwave scattering from the sea surface, and at the same time, we address the issue of the filtered mean square slope (mss) conventionally used in the geometrical optics model. GO4 is a simple correction of this last model, taking into account the diffraction correction induced by the rough surface through what we call an effective mean square curvature (msc). We evaluate the effective msc as a function of the surface wavenumber spectrum and the radar frequency and show that GO4 reaches the same accuracy as the physical optics model in a wide range of incidence and frequency bands with the sole knowledge of the mss and msc parameters. The key point is that the mss entering in GO4 is not the filtered but the total slope. We provide estimation of the effective msc on the basis of classical sea spectrum models. We also evaluate the effective msc from near-nadir satellite data in various bands and show that it is consistent with model predictions. Non-Gaussian effects are discussed and shown to be incorporated in the effective msc. We give some applications of the method, namely, the estimation of the total sea surface mss and the recalibration of relative radar cross sections.
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