NDLI: Effect of non-Gaussian properties of the sea surface on the low-incidence radar backscatter and its inversion in terms of wave spectra by an ocean wave spectrometer

Content Provider	Springer Nature Link
Author	Chen, Ping Yin, Qiaohua Huang, Ping
Copyright Year	2015
Abstract	The principle of ocean wave spectrometers was first presented several decades ago to detect the directional wave spectrum with real-aperture radar (Jackson, 1981). To invert wave spectra using an ocean wave spectrometer, for simplicity, the hydrodynamic forcing and wave-wave interaction effect are neglected and a Gaussian slope probability density function (pdf) is used to calculate the normalized backscattering cross-section (σ 0) of the ocean surface. However, the real sea surface is non-Gaussian. It is not known whether the non-Gaussian property of the sea surface will affect the performance of the inversion of the wave spectrum if following existing inversion steps and methods. In this paper, the pdf of the sea surface slope is expressed as a Gram-Charlier fourth-order expansion, which is quasi-Gaussian. The modulation transfer function (MTF) is derived for a non-Gaussian slope pdf. The effects of non-Gaussian properties of the sea surface slope on the inversion process and result are then studied in a simulation of the SWIM (Surface Waves Investigation and Monitoring) instrument configuration to be used on the CFOSAT (China-France Oceanography Satellite) mission. The simulation results show that the mean trend of σ 0 depends on the sea slope pdf, and the peakedness and skewness coefficients of the slope pdf affect the shape of the mean trend of σ 0 versus incidence and azimuth; owing to high resolution of σ 0 in the range direction, MTF obtained using the mean trend of σ 0 is almost as accurate as that set in the direct simulation; in the inversion, if ignoring the non-Gaussian assumption, the inversion performances for the wave spectrum decrease, as seen for an increase in the energy error of the inverted wave slope spectrum. However, the peak wavelength and wave direction are the same for inversions that consider and ignore the non-Gaussian property.
Starting Page	1142
Ending Page	1156
Page Count	15
File Format	PDF
ISSN	02544059
Journal	Chinese Journal of Oceanology and Limnology
Volume Number	33
Issue Number	5
e-ISSN	19935005
Language	English
Publisher	Science Press
Publisher Date	2015-09-08
Publisher Place	Heidelberg
Access Restriction	Subscribed
Subject Keyword	slope probability density of the sea surface ocean wave spectrometer non-Gaussian directional wave spectrum energy error Oceanography
Content Type	Text
Resource Type	Article
Subject	Water Science and Technology Oceanography

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