Brewster Angle Damping Observed in the TerraSAR-X Synthetic Aperture Radar Images of Man-Made Targets

Ouchi, Kazuo,Yang, Chan-Su IEEE 2018 IEEE geoscience and remote sensing letters Vol.15 No.4

<P>This letter shows the phenomena of Brewster angle damping and its implication observed in the synthetic aperture radar (SAR) images of concrete constructions, such as a bridge and seawalls over the sea. The Fresnel reflection coefficient of concrete material is close to zero at the Brewster angle for X-band V-polarization microwave. The TerraSAR-X images of Tokyo Bay, Japan, at small incidence angles (20.1°–21.4°) showed strong double-bounce reflection between the sea surface and coastal structure with HH-polarization, whereas very little radar backscatter was observed with VV-polarization. The same little radar backscatter was seen in the images of concrete walls on ground and swamp areas covered with reeds. This effect is illustrated with HH/VV intensity and phase difference images, and ground survey data; its implication is also suggested for a better understanding of polarimetric SAR images.</P>

Applications of Synthetic Aperture Radar and Optical Satellite to Studying Surface & Underwater Phenomena in KIOST

Chan-Su Yang,Kazuo Ouchi 해양환경안전학회 2014 해양환경안전학회 학술발표대회 논문집 Vol.2014 No.11

Velocity Estimation of Moving Targets on the Sea Surface by Azimuth Differentials of Simulated-SAR Image

양찬수,Kazuo Ouchi,김연섭 대한원격탐사학회 2010 大韓遠隔探査學會誌 Vol.26 No.3

Since the change in Doppler centroid according to moving targets brings alteration to the phase in azimuth differential signals of synthetic aperture radar (SAR) data, one can measure the velocity of the moving targets using this effect. In this study, we will investigate theoretically measuring the velocity of an object from azimuth differential signals by using range compressed data which is the interim outcome of treatment from the simulated SAR raw data of moving targets on the background of sea clutter. Also, it will provide evaluation for the elements that affect the estimation error of velocity from a single SAR sensor. By making RADARSAT-1 simulated image as a specific case, the research includes comparisons for the means of velocity measurement classified by the directions of movement in the four following cases. 1. A case of a single target without currents, 2. A case of a single target with tidal currents of 0.5 m/s, 1 m/s, and 3 m/s,3. A case of two targets on a same azimuth line moving in a same direction and velocity, 4. A case of a single target contiguous to land where radar backscatter is strong. As a result, when two moving targets exist in SAR image outside the range of approximately 256 pixels,the velocity of the object can be measured with high accuracy. However, when other moving targets exist in the range of approximately 128 pixels or when the target was contiguous to the land of strong backscatter coefficient (NRCS: normalized radar cross section), the estimated velocity was in error by 10% at the maximum. This is because in the process of assuming the target’s location, an error occurs due to the differential signals affected by other scatterers.

Accuracy Improvement of the Radar Backscatter Simulation from Sea Surface Covered by Oil Slick Using Fetch-Dependent Waveheight Spectrum: Comparison with the 2007 Heibei Spirit Case in the Yellow Sea

김태호,양찬수,Kazuo Ouchi 한국해양과학기술원 2016 Ocean science journal Vol.51 No.2

In this paper, results are presented on the comparison of X-band radar backscattering coefficient (RBC) from an oilcovered sea surface that features the Elfouhaily and Durden-Vesecky waveheight spectra. The Durden-Vesecky spectrum applies to a fully-developed sea, while the Elfouhaily spectrum accounts for the fetch of arbitrary length. Using these two waveheight spectra, a one-dimensional random rough surface is simulated by the Monte Carlo method, and the method of moments (MoM) is applied to yield the RBC. Comparison of the results with TerraSAR-X synthetic aperture radar (SAR) data acquired over the coastal waters polluted by the Hebei Spirit oil tanker shows that the Elfouhaily spectrum yields better agreement than the Durden-Vesecky spectrum for the fully-developed sea, and that the fetch-dependent Elfouhaily spectrum improves the agreement with SAR data in comparison with the fetch-independent spectrum for the fully developed sea. A possible application to estimate the amount of spilled oil is also suggested.

북극 스발바드 콩스피오르덴 해역에서 L 밴드 PALSAR 데이터를 이용한 눈과 부빙에 의한 다중편파 산란특성 해석

정정수,양찬수,Kazuo Ouchi,Kuzaki Nakamura 한국해양과학기술원 2011 Ocean and Polar Research Vol.33 No.1

This study describes measurements of fast ice recorded on May 23, 2009, in Kongsfjorden (translated as ‘Kongs Fjord’), an inlet on the west coast of Spitsbergen in the Svalbard Archipelago. Seasonal fast ice is an important feature for Svalbard fjords, both in relation to their physical environment and also the local ecosystem, since it grows seaward from the coast and remains in place throughout the winter. Ice thickness, snow, ice properties, and wind speed were measured, while SAR (Synthetic Aperture Radar) data was observed simultaneously observed two times from ALOS-PALSAR (L-band). Measured ice thickness was about 25-35 cm while the thickness of ice floe broken from fast ice was measured as 10-15 cm. Average salinity was 1.9-2.0 ppt during the melting period. Polarimetric data was used to extract H/A/alpha-angle parameters of fast ice, ice floe, snow and glacier, which was classified into 18 classes based on these parameters. It was established that the area of fast ice represents surface scattering which indicates low and medium entropy surface scatters such as Bragg and random surfaces, while fast ice covered with snow belongs to a zone of low entropy surface scattering similar to snow-covered land surfaces. The results of this study will contribute to various interpretations of interrelationships between H/A/alpha parameters and the wave scattering Phenomenon of sea ice.

On the similarity between dual- and quad-eigenvalue analysis in SAR polarimetry

Sugimoto, Mitsunobu,Ouchi, Kazuo,Nakamura, Yasuhiro Taylor Francis 2013 Remote Sensing Letters Vol.4 No.10

Study on Ship Detection Using SAR Dual-polarization Data: ENVISAT ASAR AP Mode

Yang, Chan-Su,Ouchi, Kazuo The Korean Society of Remote Sensing 2008 大韓遠隔探査學會誌 Vol.24 No.5

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. In this paper, the polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV images, In the next step, we examine the technique when the dual-polarization data are split into two multi-look images, It was shown that the inter-look cross-correlation method could be applicable in the performance improvement of small ship detection and the land masking, It was also found that a simple combination of coherence images from each co-polarised (HH) inter-look and cross-polarised (HV) inter-look data can provide much higher target-detection possibilities.

Design and Delivery of Beam Monitors for the Energy-upgraded Linac in J-PARC

Akihiko Miura,Nobuo Ouchi,Hidetomo Oguri,Kazuo Hasegawa,Tomoaki Miyao,Masanori Ikegami 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3

In the J-PARC (Japan Proton Accelerator Research Complex) linac, an energy-upgrade projecthas started to achieve a design beam power of 1 MW at the exit of the downstream synchrotron. To account for the significant beam parameter upgrades, we will use the newly-fabricated beammonitors for the beam commissioning. This paper discusses the design and assembly of the beamposition monitor, phase monitor, current monitor, transverse profile monitor, and beam loss monitorfor the energy-upgraded linac. We periodically installed the newly-fabricated monitors for theupgraded beam line, as well as for longitudinal matching, because of the frequency jump betweenthe original RF cavity and the newly-developed cavity. We employed two debunchers to correctfor momentum spread and jitter. To account for the new debunchers, we fabricated and installedadditional pairs of phase monitors in order to tune the debunchers to the adequate RF set point. Finally, we propose commissioning plans to support the beam monitor check. We will begin toestablish the 181-MeV operation to confirm the proper functioning of beam monitors. Herein, wewill examine the response to changes of the knobs that control the quadrupole magnets after theenergy upgrade. After proper functioning of the beam monitors is confirmed, we will use the newbeam monitors to establish the 400-MeV acceleration operation.

Study on Ship Detection Using SAR Dual-polarization Data: ENVISAT ASAR AP Mode

Chan Su Yang,Kazuo Ouchi 大韓遠隔探査學會 2008 大韓遠隔探査學會誌 Vol.24 No.5

Preliminary results are reported on ship detection using coherence images computed from cross-correlating images of multi-look-processed dual-polarization data (HH and HV) of ENVISAT ASAR. The traditional techniques of ship detection by radars such as CFAR (Constant False Alarm Rate) rely on the amplitude data, and therefore the detection tends to become difficult when the amplitudes of ships images are at similar level as the mean amplitude of surrounding sea clutter. The proposed method utilizes the property that the multi-look images of ships are correlated with each other. Because the inter-look images of sea surface are covered by uncorrelated speckle, cross-correlation of multi-look images yields the different degrees of coherence between the images and water. In this paper, the polarimetric information of ships, land and intertidal zone are first compared based on the cross-correlation between HH and HV images. In the next step, we examine the technique when the dual-polarization data are split into two multi-look images. It was shown that the inter-look cross-correlation method could be applicable in the performance improvement of small ship detection and the land masking. It was also found that a simple combination of coherence images from each co-polarised (HH) inter-look and cross-polarised (HV) inter-look data can provide much higher target-detection possibilities.

Application of Velocity Bunching Model to Estimate Wave Height of Ocean Waves using Multiple Synthetic Aperture Radar Data

Yang, Chan-Su,Ouchi, Kazuo BioOne (Coastal Education and Research Foundation) 2017 JOURNAL OF COASTAL RESEARCH Vol.79 No.special