基于频带分割法反演电离层TEC参数

星载合成孔径雷达(SAR)系统会受到电离层带来的相位影响，降低星载SAR系统成像质量，对低频段宽带星载SAR尤其明显。为了消除电离层对星载SAR带来的相位影响，基于陆地观测技术卫星2号(ALOS-2)星载SAR数据,采用距离向频带分割法来估计电离层电子总含量(TEC)参数。验证推导距离向频带分割法的最优估计精确度，并利用ALOS-2数据，采用距离向频带分割法反演得到二维电离层TEC参数分布，分析了距离向分辨单元数对反演精确度的影响。另外，分析了雷达图像不同区域采用距离向频带分割法的估计精确度。结果表明频带分割法具有很强的鲁棒性，可以有效地反演电离层TEC参数分布，同时距离向分辨力单元数和成像区域场景地形起伏也影响反演电离层参数的精确度。

Retrieving ionospheric TEC based on the split-spectrum method

The ionosphere can affect the phase of spaceborne Synthetic Aperture Radar(SAR) signal, which will degrade the quality of SAR imaging, especially for the low frequency wideband spaceborne SAR. Based on Advanced Land Observing Satellite-2(ALOS-2) SAR data, the ionospheric Total Electron Content(TEC) distribution is estimated by using the split-spectrum method in order to eliminate the impact of ionosphere. Firstly, the accuracy of the split-spectrum method for retrieving ionospheric TEC is validated. Then, the two-dimensional ionospheric TEC distribution is obtained based on the split-spectrum method using ALOS-2 data. The range resolution cell effect is also analyzed. The ionopheric TEC estimation accuracies of the split-spectrum method for three different typical areas in SAR image are compared. The results show that the split-spectrum method is robust to estimate the two-dimensional ionopheric TEC effectively. The range resolution cell and different scenes in SAR image also affect the TEC estimation accuracy of the split-spectrum method.