利用SAR影像估计精细化的电离层VTEC和电子密度

垂直总电子含量（VTEC）和三维电子密度是表征电离层空间结构及其变化的重要参数,对其进行精细化的观测是深入认识整个日地空间环境和保障人类空间活动有序开展的重要基础。相比于常规观测技术，合成孔径雷达(SAR)在估计精细化VTEC和电子密度方面具有巨大的优势与潜力。然而，该项技术目前仍有一些关键科学问题尚未解决，限制了其进一步的发展。基于此，本项目拟开展基于SAR影像的精细化电离层VTEC和电子密度估计研究。项目首先开展了法拉第旋转法、距离向光谱分频法和方位向光谱分频法的VTEC估计研究；在此基础上，提出联合国际参考电离层模型（IRI）和SAR估计精细化电子密度的方法；为了验证方法的合理性，对估计的VTEC和电子密度进行基准校正与精度评定；最后，将验证后的结果应用到电离层微观异常扰动特征分析中。项目研究成果将为提升电离层科学的发展提供有力的技术支撑，具有重要的科学意义和应用价值。

Vertical total electron content (VTEC) and three-dimensional electron density are two key parameters to characterize the ionospheric spatial structure and variations. It is necessary to observe the ionospheric VTEC and electron density for better understanding the whole spatial environments and human spatial activities. Compared with the other observation techniques, SAR has shown its advantage and potential on imaging the VTEC and electron density with fine resolution. However, there are still some problems to be solved for this technology, which limits its further development. Based on this background, this project attempts to develop the efficient methods to estimate the VTEC and electron density based on SAR imagery. Firstly, three methods, including Faraday rotation, split range-spectrum and split azimuth-spectrum, are developed to estimate the VTEC; then, high-spatial-resolution three-dimensional electron density is estimated by combing of SAR and IRI model; after that, the estimated VTEC and three-dimensional electron density are calibrated and evaluated to prove its reliability; finally, the microscopic ionospheric anomalies are analyzed to explore the disaster-atmosphere - ionospheric coupling mechanism. This research will provide of strong support to the development of ionospheric science, and also shows the important scientific significance and application value.