顾及土壤热传导-对流效应的InSAR冻土活动层厚度估计  

InSAR estimation of permafrost active layer thickness considering soil conduction-convection heat transfer effect

作　　者：杨沙 王琪洁[1,2] 李佳晨 张亚 YANG Sha;WANG QiJie;LI JiaChen;ZHANG Ya(School of Geosciences and Info-Physics,Central South University,Changsha 410083,China;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education,Central South University,Changsha 410083,China)

机构地区：[1]中南大学地球科学与信息物理学院,长沙410083 [2]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,长沙410083

出　　处：《地球物理学报》2024年第7期2568-2581,共14页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2022YFB3903602);国家自然科学基金(41925016,42330112);湖南省教育厅科学研究项目(21A0006)资助。

摘　　要：冻土活动层厚度(Active Layer Thickness,ALT)的变化是反映青藏高原多年冻土发育情况及其状态的一个重要指标,监测活动层厚度变化对寒区景观稳定发展、碳循环等方面具有非常重要的意义.由于合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar,InSAR)技术具有大范围、高精度、高时空分辨率等优势,近年来逐渐被用于反演活动层厚度.已有研究中基于InSAR和土壤一维热传导模型的活动层厚度估计方法,没有充分考虑到冻土中土壤水分对流引起的热量传递.因此本文提出了基于InSAR时序形变及土壤热传导-对流模型的活动层厚度估计方法,利用土壤热传导-对流模型建立InSAR探测的最大融沉形变与最高地温之间的滞后时间与活动层厚度之间的相关关系,实现了由滞后时间直接推算大范围、高分辨率的冻土活动层厚度.本文以青藏高原五道梁多年冻土区为例,利用116景Sentinel-1影像图作为实验数据,估计了该地区2017—2020年的平均活动层厚度.结果表明,活动层厚度值范围为0~7.0 m,平均活动层厚度为3.06 m,与已有研究中相近时间段相关成果及观测数据结果一致.本文方法兼顾冻土水热过程,证明了土壤热传导-对流模型在冻土活动层厚度反演中具有良好的应用前景,可用于青藏高原其他偏远地区的高空间分辨率活动层厚度反演.The change of permafrost active layer thickness(ALT)is an important index to reflect the development and status of permafrost in Tibetan Plateau.Monitoring the change of ALT is of great significance to the stable development of the cold region landscape,carbon cycle,etc.Since the Interferometric Synthetic Aperture Radar(InSAR)technology has the advantages of large range,high precision and high spatial-temporal resolution,it has been gradually used to invert ALT in recent years.The existing ALT estimation methods based on InSAR and one-dimensional heat transfer model of soil do not fully consider the heat transfer caused by soil moisture convection in permafrost.Therefore,this paper presents a method to estimate ALT over permafrost based on InSAR observation and soil conduction-convection heat transfer model.Using the time lags between the maximum periodic feature of InSAR-observed surface deformation over permafrost and maximum land surface temperature,the correlation between time lags and ALT is established based on the soil conduction-convection heat transfer model.Finally,by exploiting the time lags and the soil conduction-convection heat transfer model,we estimate the large-scale and high-resolution ALTs.Taking Wudaoliang permafrost region of Tibetan Plateau as an example,116 Sentinel-1 images are exploited by the method to estimate average ALT in this region from 2017 to 2020.In the case study,the ALTs are ranging from 0 to 7.0 m and with an average of 3.06 m.The results are compatible with those related observations and estimations in existing studies.Our results demonstrate that soil conduction-convection heat transfer model has good prospect in ALT estimation over permafrost regions.The presented method takes into account the hydrothermal process of permafrost and can potentially be used for deriving high-resolution ALTs in other remote areas similar to Tibetan Plateau.

关 键 词：冻土 土壤热传导-对流模型 青藏高原 活动层厚度 INSAR 

分 类 号：P237[天文地球—摄影测量与遥感]