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Remote Sens. 2017, 9(8), 866;

Azimuth Ambiguities Removal in Littoral Zones Based on Multi-Temporal SAR Images

School of Electronic Science and Engineering, National University of Defense Technology, Sanyi Avenue, Changsha 410073, China
Author to whom correspondence should be addressed.
Academic Editors: Xiaofeng Yang, Xiaofeng Li, Ferdinando Nunziata and Alexis Mouche
Received: 31 May 2017 / Revised: 16 August 2017 / Accepted: 17 August 2017 / Published: 22 August 2017
(This article belongs to the Special Issue Ocean Remote Sensing with Synthetic Aperture Radar)
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Synthetic aperture radar (SAR) is one of the most important techniques for ocean monitoring. Azimuth ambiguities are a real problem in SAR images today, which can cause performance degradation in SAR ocean applications. In particular, littoral zones can be strongly affected by land-based sources, whereas they are usually regions of interest (ROI). Given the presence of complexity and diversity in littoral zones, azimuth ambiguities removal is a tough problem. As SAR sensors can have a repeat cycle, multi-temporal SAR images provide new insight into this problem. A method for azimuth ambiguities removal in littoral zones based on multi-temporal SAR images is proposed in this paper. The proposed processing chain includes co-registration, local correlation, binarization, masking, and restoration steps. It is designed to remove azimuth ambiguities caused by fixed land-based sources. The idea underlying the proposed method is that sea surface is dynamic, whereas azimuth ambiguities caused by land-based sources are constant. Thus, the temporal consistence of azimuth ambiguities is higher than sea clutter. It opens up the possibilities to use multi-temporal SAR data to remove azimuth ambiguities. The design of the method and the experimental procedure are based on images from the Sentinel data hub of Europe Space Agency (ESA). Both Interferometric Wide Swath (IW) and Stripmap (SM) mode images are taken into account to validate the proposed method. This paper also presents two RGB composition methods for better azimuth ambiguities visualization. Experimental results show that the proposed method can remove azimuth ambiguities in littoral zones effectively. View Full-Text
Keywords: azimuth ambiguities; littoral zones; multi-temporal; RGB composition; synthetic aperture radar (SAR); Sentinel-1 azimuth ambiguities; littoral zones; multi-temporal; RGB composition; synthetic aperture radar (SAR); Sentinel-1

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Leng, X.; Ji, K.; Zhou, S.; Zou, H. Azimuth Ambiguities Removal in Littoral Zones Based on Multi-Temporal SAR Images. Remote Sens. 2017, 9, 866.

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