长波长星载SAR探测电离层的机理与方法研究

It is of great significance for earth space science research, space information system development to achieve fine exploration of ionosphere. However, measurement of global ionosphere with high accuracy and resolution is still unachievable at present and is the trend in future. This project mainly focuses on the mechanism and method of fine ionosphere exploration with spaceborne longer wavelength synthetic aperture radar (SAR). Based on the mechanism of fine detection for total electron continent (TEC) by means of ionospheric refraction theory and the distribution regularity of time-space changed TEC, a fine inversion method of space changed TEC with spaceborne full-polarimetric SAR, as well as large-scale time changed TEC with spaceborne differential interferometric SAR, will be proposed. For small-scale time changed TEC, a fine inversion method via geosynchronous (GEO) SAR. Moreover, according to the mechanism of fine detection of electron density based on ionospheric backward scattering theory, a compressive sensing based spaceborne SAR three-dimensional imaging method of ionospheric irregularities with high resolution will be proposed. Meanwhile, the fine inversion of electron density will be investigated as well. The methods will make the resolution better than hundreds of meters and the accuracy better than 0.5TECU. The research of this program will supply principles and methods for fine ionosphere exploration using spaceborne platform.

电离层探测对于地球空间气象科学研究、空间信息系统气象保障等具有极为重要的意义。目前的全球电离层探测手段分辨率低，精度差，长波长星载合成孔径雷达能够实现全球电离层高分辨率、高精度的测量，是未来的发展趋势。本项目重点研究长波长星载SAR探测电离层的机理与方法，探究基于电波折射理论的电离层总电子量（TEC）精细探测机理及时/空变TEC分布规律，提出星载全极化SAR空变TEC精细反演方法，星载差分干涉SAR长时间尺度TEC精细反演方法，以及地球同步轨道（GEO）SAR短时间尺度TEC精细反演方法；探究基于电离层后向散射理论的小尺度不规则体电子密度探测机理，提出基于压缩感知理论的星载SAR电离层不规则体三维稀疏成像方法，在此基础上提出小尺度不规则体电子密度反演方法。拟将电离层探测的空间分辨率提高到优于百米量级，精度提高到优于0.5TECU，为天基平台电离层精细探测技术提供理论和方法支撑。

电离层高精度探测在地球空间气象科学研究、空间信息系统气象保障等领域具有重要的研究意义。传统的全球电离层探测技术具有空间分辨率低、获取精度差等劣势，本项目基于长波长星载合成孔径雷达在探测全球电离层方面的优势，重点开展了长波长星载SAR探测电离层的机理与方法研究；结合电波折射理论，完成了电离层总电子量精细探测机理以及时变、空变TEC分布规律；在此基础上，提出了全极化星载SAR空变TEC精细反演新方法、长时间尺度下的TEC精细反演新方法以及短时间尺度下的TEC精细反演新方法；此外，针对小尺度不规则体电子密度高精度探测需求，开展了基于电离层后向散射理论的小尺度不规则体电子密度探测机理研究，提出了基于压缩感知理论的星载SAR电离层不规则体三维稀疏成像方法以及小尺度不规则体高精度反演方法。通过上述理论与方法的研究，可显著提高电离层探测的空间分辨率与TEC获取的精度，从而为天基平台电离层精细探测技术提供理论和方法支撑。