基于卫星InSAR的昆仑山口活动石冰川识别及运动特征分析

Rock glaciers are landforms developing in high mountains and are commonly regarded as visible expressions of permafrost presence in periglacial areas. Monitoring and analyzing the spatiotemporal kinematic evolution of active rock glaciers (ARGs) is important for inferring the states of permafrost degradation in high cold mountains. In view of challenges in the identification and quantitative analysis of rock glaciers with optical images, this research project intends to use Interferometric Synthetic Aperture Radar (InSAR) to systematically study the geomorphic and kinematic characteristics of ARGs in the Kunlun Pass region. This project will mainly focus on the accurate identification and long-term movement monitoring of ARGs. The basic strategy of the project is provided here. By the combined use of the interferometric phase, coherence, and satellite optical imagery, we expect to accurately identify ARGs and then interpret their key geomorphological parameters. Considering the nonlinear pattern of movement of ARGs, we will study and extend the advanced time series InSAR method to accurately retrieval the surface motion of typical ARGs in recent 20 years. We will also use the independent composition analysis (ICA) techniques to analyze the retrieved temporal displacements of ARGs by characterizing their temporal behaviors and the associated mechanism. This project aims to provide reliable approaches for the identification, monitoring, and analysis of ARGs in the large-scale region in west China with high-efficiency and high-accuracy. This proposal would also to a certain extent fill in research gaps on rock glaciers in recent 20 years in China.

石冰川是高山冰缘地区存在永久冻土的标志地貌，监测和分析活动石冰川的时空动态演变规律对探究高寒山区永久冻土退化状态意义重大。针对利用光学影像在活动石冰川识别和定量分析中面临的挑战，本项目提出利用卫星InSAR对青藏高原昆仑山口活动石冰川的地貌和运动特征展开系统研究，重点突破活动石冰川准确识别和长时序运动监测问题。项目基本思路是：联合SAR干涉相位信息、相干性信息和卫星光学影像准确识别活动石冰川并提取其边界，并基于此对其关键地貌参数进行解译；扩展面向活动石冰川非线性运动特征恢复的高级时序InSAR模型和方法，精确测量典型活动石冰川近20年来的运动速度变化；利用独立成分分析对活动石冰川时序形变展开分析，揭示昆仑山口活动石冰川的运动特征和规律。本项目旨在为大范围、高效率和高精度的识别、监测和分析我国西部活动石冰川提供可靠技术途径，研究成果可一定程度填补近20年来我国在石冰川研究中的空缺。

石冰川是高山冰缘地区存在永久冻土的标志地貌，尽管我国西部高寒山区石冰川发育丰富，但其分布和运动状况尚未得到系统的调查和研究。本项目针对利用光学影像在活动石冰川识别和定量分析中面临的挑战，提出利用卫星合成孔径雷达干涉(InSAR)对青藏高原内陆活动石冰川的地貌和运动特征展开系统研究，重点突破活动石冰川准确识别和长时序运动监测难题。本项目在石冰川地貌类型判识、时空运动特征恢复和时序InSAR观测误差校正等多个方面取得了进展，提出了联合时序InSAR和光学影像地貌解译的石冰川编目方法，构建了成套InSAR大气延迟误差改正模型，并结合现场观测数据分析了昆仑山口石冰川分布与运动特征，评估了昆仑山口典型石冰川地貌失稳对青藏铁路的影响。项目研究发现利用卫星InSAR技术定量估计冰缘地貌单元的运动特征，能够更好地帮助确定它们的类型。基于地貌特征和基于运动特征两种思路编目的活动石冰川关键地貌参数有较大差异，但基于InSAR运动特征的编目方法具有更高效和准确的优势。项目基于高分辨率光学、SAR和历史间谍卫星影像等多源遥感数据恢复了昆仑山口典型活动石冰川近数十年的运动特征，发现其近10年运动速度增加2倍，结合崩塌动力学模型模拟分析发现其失稳滑脱对青藏铁路存在潜在致灾影响。本项目提出的联合遥感动态过程监测和静态地貌学解译的冰缘地貌研究思路，对进一步深化了解我国高寒山区冰缘地貌的分布和演化规律具有重要意义。