LT-1A卫星全极化SAR辐射与极化系统误差稳定性分析:以热带雨林场景为例  

Evaluation of Radiometric and Polarimetric Errors in the LT-1A Satellite Data Based on Tropical Forests in the Amazon

作　　者：史磊[1] 孙维东[1] 杨乐[2] 杨杰[1] 赵伶俐[3] 李平湘[1] 刘亚波 SHI Lei;SUN Weidong;YANG Le;YANG Jie;ZHAO Lingli;LI Pingxiang;LIU Yabo(State Key Laboratory of Surveying,Mapping and Remote Sensing Information Engineering,Wuhan University,Wuhan 430072,China;The school of Geo-Science and Technology,Zhengzhou University,Zhengzhou 450001,China;School of Remote Sensing Information Engineering,Wuhan University,Wuhan 430072,China;Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100094,China)

机构地区：[1]武汉大学测绘遥感信息工程国家重点实验室,武汉430072 [2]郑州大学地球科学与技术学院,郑州450001 [3]武汉大学遥感信息工程学院,武汉430072 [4]中国科学院空天信息创新研究院,北京100094

出　　处：《雷达学报(中英文)》2025年第2期405-423,共19页Journal of Radars

基　　金：国家自然科学基金(U22A2010,42071295,61971318,42171442,U2033216);深圳科技创新重点项目(JCYJ20200109150833977);自然资源部国土卫星遥感应用重点实验室经费资助(KLSMNR-202110);国家重点研发计划(2022YFB3903605);中央高校基本科研业务费专项资金资助;资源与环境信息系统国家重点实验室开放基金。

摘　　要：作为中国新一代天基长波SAR的代表,陆地探测1号01卫星(LT-1A)于2022年1月发射进入太阳同步轨道。LT-1A搭载的长波合成孔径雷达(SAR)工作在L波段,具备单极化、线性双极化、紧缩双极化、全极化等对地观测能力。现有研究主要侧重于LT-1A重轨干涉数据获取能力以及数字高程模型、沉降产品的生产精度评价,对LT-1A的辐射精度、地物极化信息保持能力的研究较为缺乏。该文以热带雨林植被为观测对象,通过不依赖人工定标器的自主定标方法对LT-1A全极化数据辐射误差、极化误差的稳定性进行评价与分析。实验表明:LT-1A传感器的辐射稳定性较好、极化精度优于国际对地观测组织(CEOS)推荐指标。持续对地观测1000 km内归一化雷达截面(NRCS)误差波动小于1 dB(3倍标准差)、5天内重返观测时辐射误差波动小于0.5 dB(3倍标准差);全极化观测模式下系统串扰低于-35 dB甚至达到-40 dB,交叉极化通道不平衡优于0.2 dB与2°,同通道不平衡优于0.5 dB与10°;系统噪声介于-42~-22 dB,平均系统等效热噪声优于-25 dB,热噪声水平随持续对地观测时长的增加有升高。此外,该研究验证了电离层对LT-1A极化数据质量的影响:5°法拉第旋转角造成的图像退化与-20 dB系统串扰带来的影响相当,而3°~20°法拉第旋转角在中、低纬度较为常见,这将带来-21.16~-8.78 dB的极化通道间扰动,即电离层对全极化数据质量的退化相较传感器-40 dB的串扰更为严重。As a representative of China’s new generation of space-borne long-wavelength Synthetic Aperture Radar(SAR),the LuTan-1A(LT-1A)satellite was launched into a solar synchronous orbit in January 2022.The SAR onboard the LT-1A satellite operates in the L band and exhibits various earth observation capabilities,including single-polarization,linear dual-polarization,compressed dual-polarization,and quadpolarization observation capabilities.Existing research has mainly focused on LT-1A interferometric data acquisition capabilities and the accuracy evaluation of digital elevation models and displacement measurements.Research on the radiometric and polarimetric accuracy of the LT-1A satellite is limited.This article uses tropical rainforest vegetation as a reference to evaluate and analyze the radiometric error and polarimetricstability of the LT-1A satellite in the full polarization observation mode through a self-calibration method that does not rely on artificial calibrators.The experiment demonstrates that the LT-1A satellite has good radiometric stability and polarimetric accuracy,exceeding the recommended specifications of the International Organization for Earth Observations(Committee on Earth Observation Satellites,CEOS).Fluctuations in the Normalized Radar Cross-Section(NRCS)error within 1,000 km of continuous observation are less than 1 dB(3σ),and there are no significant changes in system radiometric errors of less than 0.5 dB(3σ)when observation is resumed within five days.In the full polarization observation mode,the system crosstalk is less than-35 dB,reaching as low as-45 dB.Further,the cross-polarization channel imbalance is better than 0.2 dB and 2°,whilethe co-polarization channel imbalance is better than 0.5 dB and 10°.The equivalent thermal noise ranges from-42~-22 dB,and the average equivalent thermal noise of the system is better than-25 dB.The level of thermal noise may increase to some extent with increasing continuous observation duration.Additionally,this study found that the ionosphere sign

关 键 词：陆地探测1号卫星 辐射误差 极化误差 热带雨林 合成孔径雷达 

分 类 号：TN957.51[电子电信—信号与信息处理]