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A novel synthetic aperture radar scattering model for sea surface with breaking waves

Acta Oceanologica Sinica 2022年第4期41卷 138-145页

作者： Xiaochen Wang Yuxin Hu Bing Han Wei Tian Chunhua Zhang Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China Key Laboratory of Technology in Geo-spatial Information Processing and Application System Chinese Academy of SciencesBeijing 100190China The box51111 Beijing 100190China

In this study a novel synthetic aperture radar(SAR)scattering model for sea surface with breaking waves is proposed.Compared with existing models,the proposed model considers an empirical relationship between wind speed and wave breaking scattering to present the contribution of wave breaking.Moreover,the scattering weight factor p,and wave breaking rate q,are performed to present the contribution of the quasi-specular scattering term,Bragg scattering term,and wave breaking scattering term to the total scattering from the sea surface.To explore the modeling accuracy of sea-surface scattering,a simulated normalized radar cross-section(NRCS)and measured NRCS are compared.The proposed model generated the simulated NRCS and a matching GF-3 dataset was used for the measured NRCS.It was revealed that the performance of the VV polarization of our model was much better than that of HH polarization,with a correlation of 0.91,bias of-0.14 dB,root mean square error(RMSE)of 1.26 dB,and scattering index(SI)of-0.11.In addition,the novel model is explored and compared with the geophysical model of CMODs and satellite-measured NRCS from GF-3 SAR wave mode imagery.For an incidence angle 40°–41°,the relationship between the NRCS and wind speed,relative wind direction is proposed.As with the SAR-measured NRCS,the performance of VV polarization was much better than HH polarization,with a correlation of 0.99,bias of-0.25 dB,RMSE of 0.64 dB,and SI of-0.04.

关键词： synthetic aperture radar scattering model sea surface wave breaking

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Physical model of acoustic forward scattering by cylindrical shell and its experimental validation

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Chinese Physics B 2010年第5期19卷 369-377页

作者：雷波杨坤德马远良 College of Marine Northwestern Polytechnical University

Research on the underwater target scattering can provide important theoretical support for target detection. The scattering model of cylindrical shell is established in this paper. It is found that the forward target strength is much stronger and varies with angles of incident wave less significantly than backward target strength. The received forward signal strength fluctuates with the target moving due to the interference between direct signal and scattering signal, which is most significant when the target approaches the baseline. An experiment is carried out in an anechoic tank to validate the scattering model. The method of acquisiting forward scattering in the tank is proposed. The forward and the backward target strengths are achieved by using the pulse compression technology, and they axe about 3dB less than the modeling results. The forward scattering phenomena of quiescent and moving targets are measured, which are similar to modeling results with different target types.

关键词： scattering model forward scattering target strength shell

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Bi-Spectrum scattering model for Conducting Randomly Rough Surface

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Tsinghua Science and Technology 2002年第3期7卷 309-316页

作者：刘宁李宗谦 State Key Laboratory on Microwave and Digital Communications Department of Electronic Engineering Tsinghua University Beijing 100084 China

A scattering model is developed to predict the scattering coefficient of a conducting randomly rough surface by analyzing the randomly rough surface in the spectral domain using the bi-spectrum method. For common randomly rough surfaces without obvious two-scale characteristics, a scale-compression filter can divide the auto-correlation spectrum into two parts with different correlation lengths. The Kirchhoff approximation and the small perturbation method are used to obtain the surface field, then a bistatic scattering model, the bi-spectrum model (BSM), is used to derive an explicit expression from the surface field. Examples using the integral equation model (IEM), finite difference of the time domain (FDTD) method, and BSM show that the BSM accuracy is acceptable and its range of validity is similar to IEM. BSM can also be extended to a scattering model for dielectric randomly rough surfaces.

关键词： microwave remote sensing conducting randomly rough surface scattering model spectral domain bi-spectrum scattering model

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Adaptive polarimetric decomposition using incoherent ground scattering models without reflection symmetry assumption

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Geo-Spatial Information Science 2015年第1期18卷 1-10页

作者： Xiaoguang CHENG Wenli HUANG Jianya GONG Nanjing Research Institute of Electronics Engineering 99 Houbiaoying RoadNanjing 210007China State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan University129 Luoyu RoadWuhan 430079China Department of Geographical Sciences University of MarylandCollege ParkMD 20742USA

Most of the current incoherent polarimetric decompositions employ coherent models to describe ground scattering;however,this cannot truly reflect the fact especially in natural ground surfaces.This paper proposes a highly adaptive decomposition with incoherent ground scattering models(ADIGSM).In ADIGSM,Neumann’s adaptive model is employed to describe volume scattering,and to explain cross-polarized power in remainder matrix,so that we can obtain orientation angle randomness for both volume scattering and the dominant ground scattering.The computation of volume scattering parameters is strictly constrained for non-negative eigenvalues,while the volume scattering parameters that explain the most cross-polarized power are selected.When applying ADIGSM to NASA’s UAVSAR data,the negative component powers were obtained in quite a few forest pixels.Compared with several newest decompositions,the volume scattering power is obviously lowered,especially in areas dominated by surface scattering or double bounce scattering.The orientation angle randomness of each component is reasonable as well.ADIGSM has potential to be applied in the fields such as PolSAR image classification,land cover mapping,speckle filtering,soil moisture and roughness estimation,etc.

关键词： polarimetric synthetic aperture radar(PolSAR) polarimetric decomposition non-negative eigenvalue decomposition(NNED) scattering model

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Sea Roughness Trend Measurement using Power Waveforms of GPS Direct and Reflected Signals

Sea Roughness Trend Measurement using Power Waveforms of GPS...

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第37届中国控制会议

作者： Mohammad Shohidul Islam Dongkai Yang S M Injamamul Haque Masum Sultana Easmin Siddika Rodolfo D.Moreno Santillan School of Electronic and Information Engineering Beihang University School of Economics and Management Beihang University International School Beihang University

Sea roughness trend measurement is important to understand the present and future sea state conditions. It can be considered as an advance process of sea surface bulletin and sea weather forecasting. In this research, sea surface roughness trend is measured according to the nature of power waveforms of GPS direct and reflected signals. Remote sensing technique is proposed to generate power waveforms of GPS direct and reflected signals. This technique has been utilizing as an effective technique to understand ＆ determine the sea state monitoring, especially for sea wind estimation, sea wave height measurement, sea roughness measurement and so on. The power waveforms are generated by Z-V scattering model. Mainly, two models are used to perform the whole process. At first, wave spectrum model is used to find sea surface slopes（up ＆ cross variance） and then scattering model is used to generate power waveforms using the up and cross variance. Sea surface roughness trend is determined using the features of the amplitudes of these waveforms. From the analysis, it is obtained that features of power waveforms are sharply different for different ocean surface weather conditions, which means that there is a relationship between amplitude of the waveforms and sea surface weather conditions. This relation is used to measure the sea roughness conditions. The results of this paper are found good performance compared to sea surface wind. The results of this research have also provided the preliminary idea about the sea surface and in future, the idea can help to measure the others ocean parameters.

关键词： GPS direct ＆ reflected signals power waveforms scattering model sea roughness trend

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Sea Wind Speed Estimation from Power Waveforms of GNSS-R Delay Signals of Beidou MEO Satellite

Sea Wind Speed Estimation from Power Waveforms of GNSS-R Del...

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第37届中国控制会议

作者： Mohammad Shohidul Islam Dongkai Yang Sultana Easmin Siddika Rodolfo D.Moreno Santillan S M Injamamul Haque Masum School of Electronic and Information Engineering Beihang University School of Economics and Management Beihang University International School Beihang University

This paper focuses the characteristics of power waveforms according to different wind speed of sea surface and then sea wind speed is estimated from the amplitude of power waveforms. The power waveforms are generated from the delay signals of Beidou MEO satellite. The remote sensing of GNSS concept is utilized to get information from sea surface. Because, this technique has been already proved as an effective tool to retrieve significant information from earth’s surface since last twenty years. Still now, it has been utilizing as an advance technique for sea state monitoring, i.e. sea wind speed ＆ direction, sea wave height, sea roughness measurement and so on. It is mainly generated the waveforms of Beidou MEO satellite for direct and reflected signals. It is obtained that the amplitude ＆ shape of these power waveforms are varying according to wind speed. It is indicated that there is a sharp relationship between the amplitude of the waveforms and sea wind speeds. Two models are used to generate the waveforms from reflected signals. The wave spectrum model is used to find sea surface slopes i.e. up ＆ cross variance and these up ＆ cross variance is used as input on Z-V scattering model to generate power waveforms. The real wind speed of the experiment site of GNSS-R data collection for same time domain is also collected. The linear regression method is used to established a relationship between wind speeds and amplitudes of the waveforms. This relation is used to measure the sea wind speed. It is found that estimated wind speeds are matched closely with real wind speed and model waveforms performs good results with real data waveforms.

关键词： Power waveforms reflected signals scattering model wave spectrum model wind speed

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