{"title":"电离层法拉第旋转影响下低频星载全极化SAR数据的改进处理方法","authors":"Xun Wang;Yunhua Zhang;Dong Li","doi":"10.1109/JSTARS.2025.3581144","DOIUrl":null,"url":null,"abstract":"Spaceborne full-polarimetric (FP) synthetic aperture radar (SAR) system operating at low frequency (such as L- or P-band) is a powerful microwave sensor used to capture the Earth’s surface information. However, the application effectiveness of the data acquired by such a sensor depends on the processing for the effects of ionospheric Faraday rotation (FR) and possibly-existing certain system errors. This article develops an improved processing method for low-frequency spaceborne FP SAR data affected by FR in the presence of additive noise to generate the 3 × 3 coherency matrix (CM) used for polarimetric analysis. The key to this method is an improved dichotomy of the FR corrected 4 × 4 CM obtained by directly correcting the measured 4 × 4 CM with the estimated FR. The dichotomy is obtained by solving an optimal dichotomy of the FR corrected 4 × 4 CM based on the Schur complement of a 4 × 4 matrix under two constraints with clear physical significance. Specifically, the two decomposed components are Hermitian and positive semidefinite, while the component related to additive noise possesses the smallest trace. From the perspective of polarimetric scattering entropy and the trace of the second component, the effectiveness and robustness of the improved processing method featuring the proposed dichotomy is tested on diverse L-band ALOS PALSAR and ALOS-2 PALSAR-2 FP acquisitions by comparing it with the processing method holding the same basic steps but applying the commonly used direct dichotomy. Experimental results indicate that the improved processing method can effectively alleviate the influence of additive noise on the generated 3 × 3 CM.","PeriodicalId":13116,"journal":{"name":"IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing","volume":"18 ","pages":"15774-15788"},"PeriodicalIF":4.7000,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11045077","citationCount":"0","resultStr":"{\"title\":\"An Improved Processing Method for Low-Frequency Spaceborne Full-Polarimetric SAR Data Affected by Ionospheric Faraday Rotation\",\"authors\":\"Xun Wang;Yunhua Zhang;Dong Li\",\"doi\":\"10.1109/JSTARS.2025.3581144\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Spaceborne full-polarimetric (FP) synthetic aperture radar (SAR) system operating at low frequency (such as L- or P-band) is a powerful microwave sensor used to capture the Earth’s surface information. However, the application effectiveness of the data acquired by such a sensor depends on the processing for the effects of ionospheric Faraday rotation (FR) and possibly-existing certain system errors. This article develops an improved processing method for low-frequency spaceborne FP SAR data affected by FR in the presence of additive noise to generate the 3 × 3 coherency matrix (CM) used for polarimetric analysis. The key to this method is an improved dichotomy of the FR corrected 4 × 4 CM obtained by directly correcting the measured 4 × 4 CM with the estimated FR. The dichotomy is obtained by solving an optimal dichotomy of the FR corrected 4 × 4 CM based on the Schur complement of a 4 × 4 matrix under two constraints with clear physical significance. Specifically, the two decomposed components are Hermitian and positive semidefinite, while the component related to additive noise possesses the smallest trace. From the perspective of polarimetric scattering entropy and the trace of the second component, the effectiveness and robustness of the improved processing method featuring the proposed dichotomy is tested on diverse L-band ALOS PALSAR and ALOS-2 PALSAR-2 FP acquisitions by comparing it with the processing method holding the same basic steps but applying the commonly used direct dichotomy. Experimental results indicate that the improved processing method can effectively alleviate the influence of additive noise on the generated 3 × 3 CM.\",\"PeriodicalId\":13116,\"journal\":{\"name\":\"IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing\",\"volume\":\"18 \",\"pages\":\"15774-15788\"},\"PeriodicalIF\":4.7000,\"publicationDate\":\"2025-06-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11045077\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://ieeexplore.ieee.org/document/11045077/\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENGINEERING, ELECTRICAL & ELECTRONIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing","FirstCategoryId":"5","ListUrlMain":"https://ieeexplore.ieee.org/document/11045077/","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, ELECTRICAL & ELECTRONIC","Score":null,"Total":0}
An Improved Processing Method for Low-Frequency Spaceborne Full-Polarimetric SAR Data Affected by Ionospheric Faraday Rotation
Spaceborne full-polarimetric (FP) synthetic aperture radar (SAR) system operating at low frequency (such as L- or P-band) is a powerful microwave sensor used to capture the Earth’s surface information. However, the application effectiveness of the data acquired by such a sensor depends on the processing for the effects of ionospheric Faraday rotation (FR) and possibly-existing certain system errors. This article develops an improved processing method for low-frequency spaceborne FP SAR data affected by FR in the presence of additive noise to generate the 3 × 3 coherency matrix (CM) used for polarimetric analysis. The key to this method is an improved dichotomy of the FR corrected 4 × 4 CM obtained by directly correcting the measured 4 × 4 CM with the estimated FR. The dichotomy is obtained by solving an optimal dichotomy of the FR corrected 4 × 4 CM based on the Schur complement of a 4 × 4 matrix under two constraints with clear physical significance. Specifically, the two decomposed components are Hermitian and positive semidefinite, while the component related to additive noise possesses the smallest trace. From the perspective of polarimetric scattering entropy and the trace of the second component, the effectiveness and robustness of the improved processing method featuring the proposed dichotomy is tested on diverse L-band ALOS PALSAR and ALOS-2 PALSAR-2 FP acquisitions by comparing it with the processing method holding the same basic steps but applying the commonly used direct dichotomy. Experimental results indicate that the improved processing method can effectively alleviate the influence of additive noise on the generated 3 × 3 CM.
期刊介绍:
The IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing addresses the growing field of applications in Earth observations and remote sensing, and also provides a venue for the rapidly expanding special issues that are being sponsored by the IEEE Geosciences and Remote Sensing Society. The journal draws upon the experience of the highly successful “IEEE Transactions on Geoscience and Remote Sensing” and provide a complementary medium for the wide range of topics in applied earth observations. The ‘Applications’ areas encompasses the societal benefit areas of the Global Earth Observations Systems of Systems (GEOSS) program. Through deliberations over two years, ministers from 50 countries agreed to identify nine areas where Earth observation could positively impact the quality of life and health of their respective countries. Some of these are areas not traditionally addressed in the IEEE context. These include biodiversity, health and climate. Yet it is the skill sets of IEEE members, in areas such as observations, communications, computers, signal processing, standards and ocean engineering, that form the technical underpinnings of GEOSS. Thus, the Journal attracts a broad range of interests that serves both present members in new ways and expands the IEEE visibility into new areas.