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Analysis of microwave backscattering from nonlinear sea surface with currents: doppler spectrum and SAR images

Published online by Cambridge University Press:  29 May 2020

Xiang Su*
Affiliation:
China Academy of Space Technology, Xi'an, China
Xiaoxiao Zhang
Affiliation:
School of Electronic Engineering, Xi'an University of Post & Telecommunications, Xi'an, China
Hongxing Dang
Affiliation:
China Academy of Space Technology, Xi'an, China
Xiaomin Tan
Affiliation:
China Academy of Space Technology, Xi'an, China
*
Author for correspondence: Xiang Su, E-mail: gabriel1861@163.com

Abstract

Electromagnetic scattering from the sea surface is of great significance in radar detection, target recognition, ocean remote sensing, etc. By introducing the action spectrum, the modified spatio-temporal variation wave spectrum is used to establish a nonlinear sea surface with currents in this paper. Traditional capillary wave modification facet scattering model (CWMFSM) can only calculate the backscattering from the wind-driven sea surface. By using the new spatio-temporal variation wave spectrum to modify the scattering amplitude of every facet, the new CWMFSM can be used to calculate the nonlinear sea surface scattering with surface currents. Therefore, the model simultaneously considers the modulation of sea surface wind and currents to the radar back echo. The dependence of backscattering coefficient from nonlinear sea surface on the incident angle and the polarization are discussed. The results verify that the nonlinear model is more consistent with the measurement data. This paper also investigates the Doppler spectrum characteristics of the sea with currents. It is found that the effect of wave–current interaction on Doppler spectra is weaker than that of wave–wave interaction. The SAR images of nonlinear sea surfaces are also simulated and different bands, polarizations, and baseline length effects on sea current detection performance of along-track interference SAR are analyzed.

Type
Research Paper
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2020

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