星载SAR电离层探测研究综述

计一飞; 董臻; 张永胜; 熊超; 毛文飞; 王成

doi:10.12000/JR24172

星载SAR电离层探测研究综述

DOI: 10.12000/JR24172

计一飞¹,
董臻^1, ,,
张永胜¹,
熊超²,
毛文飞³,
王成⁴

1.
国防科技大学电子科学学院长沙 410073
2.
武汉大学电子信息学院武汉 430072
3.
西南交通大学地球科学与工程学院成都 611756
4.
中国空间技术研究院钱学森空间技术实验室北京 100094

基金项目: 国家自然科学基金(62101568, 62371460, 62471474, 42074225)，湖南省自然科学基金(2024JJ4046)，博士后创新人才支持计划(BX20230473)，湖南省科技创新计划资助-湖湘青年英才(2024RC3122)，国防科技大学科研计划项目(ZK21-06)

详细信息

作者简介:
计一飞，博士，副教授，主要研究方向为雷达信号处理以及电离层传播效应等

董　臻，博士，研究员，博士生导师，主要研究方向为SAR系统设计和处理、地面动目标监测和数字波束形成等

张永胜，博士，正高级工程师，博士生导师，主要研究方向为SAR系统设计及信号处理、电离层传播效应等

熊　超，博士，教授，博士生导师，主要研究方向为电离层物理、电离层-热层耦合、电离层不规则结构及其对导航信号的影响等

毛文飞，博士，副研究员，主要研究方向为InSAR电离层误差校正、地理灾害监测等

王　成，博士，高级工程师，主要研究方向为电离层电波传播、电离层对SAR的影响及电离层探测等

通讯作者:
董臻 dongzhen@vip.sina.com

责任主编：禹卫东 Corresponding Editor: YU Weidong
中图分类号: TN957
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出版历程
- 收稿日期: 2024-08-21
- 修回日期: 2024-09-19
- 网络出版日期: 2024-11-14

Research Overview on Ionospheric Probing Based on Spaceborne Synthetic Aperture Radars

1.
College of Electronic Science and Technology, National University of Defense Technology, Changsha 410073, China
2.
College of Electronic Information, Wuhan University, Wuhan 430072, China
3.
School of Earth Science and Engineering, Southwest Jiaotong University, Chengdu 611756, China
4.
Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China

Funds: The National Natural Science Foundation of China (62101568, 62371460, 62471474, 42074225), The Hunan Provincial Natural Science Foundation (2024JJ4046), The National Postdoctoral Program of Innovative Talents (BX20230473), The Science and Technology Innovation Program of Hunan Province (2024RC3122), The Scientific Research Program of the National University of Defense Technology (ZK21-06)

More Information

Corresponding author: DONG Zhen, dongzhen@vip.sina.com

摘要

摘要: 星载合成孔径雷达(SAR)受电离层影响会出现回波信号失真、图像质量恶化、干涉/极化测量精度下降等问题，对于工作在L波段和P波段的低波段星载SAR，受电离层影响程度尤为突出。但从另一个角度看，低波段星载SAR能够捕获观测范围内不同空间尺度的电离层结构，其回波和图像数据中蕴藏丰富的电离层信息，为电离层高精度、高分辨探测提供了极大的可能性。该文围绕星载SAR背景电离层电子总量反演、电离层电子密度层析、电离层不规则体探测3个方面，回顾了利用星载SAR进行电离层探测的研究进展，总结归纳了该研究领域技术体系，强调了星载SAR具有绘制电离层局部精细结构和全球电离层态势的潜力，并展望了未来发展方向。
- 星载合成孔径雷达 /
- 干涉合成孔径雷达 /
- 极化合成孔径雷达 /
- 电离层探测 /
- 背景电离层 /
- 电离层不规则体
Abstract: The ionosphere can distort received signals, degrade imaging quality, and decrease interferometric and polarimetric accuracies of spaceborne Synthetic Aperture Radars (SAR). The low-frequency systems operating at L-band and P-band are very susceptible to such problems. From another viewpoint, low-frequency spaceborne SARs can capture ionospheric structures with different spatial scales over the observed scope, and their echo and image data have sufficient ionospheric information, offering great probability for high-precision and high-resolution ionospheric probing. The research progress of ionospheric probing based on spaceborne SARs is reviewed in this paper. The technological system of this field is summarized from three aspects: Mapping of background ionospheric total electron content, tomography of ionospheric electron density, and probing of ionospheric irregularities. The potential of the low-frequency spaceborne SARs in mapping ionospheric local refined structures and global tendency is emphasized, and the future development direction is prospected.
- Spaceborne Synthetic Aperture Radar (SAR) /
- Interferometry SAR (InSAR) /
- Polarimetric SAR (PolSAR) /
- Ionospheric probing /
- Background ionosphere /
- Ionospheric irregularities

HTML全文

图 1 L波段PALSAR, PALSAR-2图像及产品中的电离层现象

Figure 1. Ionospheric phenomena in L-band PALSAR and PALSAR-2 images and products

下载: 全尺寸图片幻灯片

图 2 基于PALSAR-2全极化图像的FR估计与TEC反演实验^[9]

Figure 2. Experiments of FR estimation and TEC extraction from PALSAR-2 full-polarimetric images^[9]

下载: 全尺寸图片幻灯片

图 3 利用FR-TEC转换方法发现极光弧现象

Figure 3. Detection of the auroral arc phenomenon based on the FR-TEC conversion method

下载: 全尺寸图片幻灯片

图 4 利用MAI反演方位向偏移的实验结果

Figure 4. Experimental results of azimuth offset mapping based on MAI

下载: 全尺寸图片幻灯片

图 5 基于全极化SAR的CIT原理及实验结果^[94,98]

Figure 5. The principle and experimental results of CIT based on full-polarimetric SAR^[94,98]

下载: 全尺寸图片幻灯片

图 6 利用PALSAR-2测量电离层不规则体闪烁参数^[111]

Figure 6. Measurement of scintillation parameters of ionospheric irregularities using PALSAR-2^[111]

下载: 全尺寸图片幻灯片

图 7 PALSAR幅度闪烁条纹提取^[123]

Figure 7. Extraction of amplitude scintillation stripes for PALSAR^[123]

下载: 全尺寸图片幻灯片

图 8 PALSAR幅度闪烁条纹功率谱估计、拟合及参数测量结果^[123]

Figure 8. Estimation, fitting and parameter measurement results for amplitude scintillation stripes for PALSAR^[123]

下载: 全尺寸图片幻灯片

表 1 基于星载SAR反演背景电离层TEC/DTEC的技术体系

Table 1. Technology mechanism of background ionospheric TEC/DTEC extraction based on spaceborne SAR

数据源	反演参数	典型方法		重要结论	参考文献
回波	TEC	自适应匹配滤波、上下调频时延测量		虽然能够实现TEC的准确测量，但要求在星载SAR场景内布设角反射器或者特定的有源定标器	[22−24]
SLC图像	TEC	距离向多视技术、最大对比度		载频降低、系统带宽增大，信杂噪比增大，TEC估计精度更高。在信杂比低于20 dB的情况下，最大对比度自聚焦方法优于距离向多视技术	[9,25−30]
SLC图像	TEC	针对双站SAR或双频SAR系统的特制方法		需要精确的轨道几何以及外部数字高程模型(Digital Elevation Model, DEM)辅助	[31−33]
全极化SAR图像或数据	FR	B&B、Freeman等FR估计器		FR估计性能受极化通道幅相不平衡、串扰、噪声影响较大，综合来看B&B估计器的性能最稳健；FR估计精度与载频、带宽无关，加窗处理可提高精度，但会损失空间分辨率；所有FR估计器都存在FR估计值模糊问题，该问题在未来P波段星载SAR系统突显	[9,34−47]
全极化SAR图像或数据	TEC	FR-TEC转换		FR-TEC转换精度与载频、地磁场矢量及FR估计精度均有关系，载频越低、纬度越高，TEC反演精度越高，FR-TEC转换在磁赤道附近会失效	[9,44,48−50]
主辅图像	DTEC、方位向偏移、干涉相位误差等	方位向偏移估计	方位向偏移追踪(Azimuth Offset Tracking, AOT)	两种方位向偏移估计方法对中小尺度的电离层空间变化非常敏感，但容易受地表形变、低相干空间缺口等问题的影响，MAI对应的方位向偏移反演精度一倍优于AOT方法，典型ALOS PALSAR参数及中等相干性条件下，MAI对应的DTEC反演精度可优于$ {10^{ - 5}} $TECU	[16,51−54]
		方位向偏移估计	子孔径干涉(Multiple Aperture Interferometry, MAI)		[55−61]
		距离向频谱分割 (Range Spectrum Split, RSS)		精度与载频、系统带宽有关，适用于电离层空间大尺度结构反演，精度劣于AOT, MAI，典型L波段PALSAR-2 85 MHz带宽参数下精度可达0.01 TECU，易受噪声和低相干区域的影响	[62−74]
		主辅图像FR及DTEC反演		类似于FR-TEC转换，精度与载频、地磁场和信噪比有关，只适用于全极化模式，并且在磁赤道附近会失效	[75,76]
		融合方法		核心是建立和求解DTEC观测矩阵方程。将AOT/MAI与RSS融合能够实现电离层DTEC不同空间尺度结构的反演，结合FR反演或IRI可以提供绝对TEC的精细信息	[77−82]

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