Improved TEC retrieval based on spaceborne PolSAR data
Improved TEC retrieval based on spaceborne PolSAR data
复制标题
基于星载PolSAR数据的改进TEC检索
DOI：
10.1002/2016rs006116
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发表时间：
2017-03-01
期刊：
影响因子：
1.6
通讯作者：
Zhao, Hai-Sheng
中科院分区：
文献类型：
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作者：
Wang, Cheng;Liu, Lu;Zhao, Hai-Sheng
众所周知，L波段星载合成孔径雷达（SAR）系统在对地观测中会受到电离层的严重影响。幸运的是，电离层的破坏性信息，总电子含量（TEC），可以恢复和删除的SAR回波模型反演，成为电离层研究的一个感兴趣的课题。考虑到系统噪声和通道相位不平衡的影响，研究了基于法拉第旋转角的高精度TEC反演方法，并将其应用于高级陆地观测卫星相控阵L波段合成孔径雷达（PALSAR）全极化数据。出于去噪的考虑，在现有的研究中，平均滤波被广泛用于去除系统噪声。为了进一步降低噪声的影响，本文提出了一种快速全变分（FTV）去噪方法。利用PALSAR全极化数据进行了一系列仿真实验，结果表明FTV去噪方法能够有效地抑制噪声，并显著降低去噪后的标准差。针对信道相位不平衡误差，提出了一种新的基于圆基协方差矩阵的法拉第估计器。理论分析和仿真结果表明，与以往的估计器相比，该估计器能够在信道相位不平衡误差占主导的情况下获得最佳性能。因此，当相位不平衡是域误差时，所提出的估计器可以作为TEC检索的候选方法。
It is well known that for Earth observations, the spaceborne synthetic aperture radar (SAR) systems at L-band can be seriously affected by the ionosphere. Fortunately, the destructive ionospheric information, total electron content (TEC), can be retrieved and removed by model inversion from SAR echoes and becomes a subject of interest for ionospheric research. Considering the system noise and channel phase imbalance, this paper focuses on accurate TEC retrieval from the Faraday rotation angle, which is embedded in Advanced Land Observing Satellite phased array L-band synthetic aperture radar (PALSAR) full-pol data. For the consideration of denoising, averaging filtering is widely used in existing studies to remove the system noise. In order to further reduce the noise effects, a fast total variation (FTV) denoising method is applied in this paper. By using the PALSAR full-pol data sets, a series of simulation results show that the FTV denoising is effective for noise suppression and markedly reduce the standard deviation. For the error of channel phase imbalance, a new Faraday estimator based on the covariance matrix of circular basis is proposed. Compared with previous estimators, theoretical analysis and simulation results show that this new estimator can give the best performance for sensors that are dominated by channel phase imbalance errors. Thus, the proposed estimator can be a candidate method for TEC retrieval when phase imbalance is the domain error.