阿尔金断裂带宽幅InSAR对流层延迟估计方法评估

合成孔径雷达干涉测量（interferometric synthetic aperture radar, InSAR）的时序分析是监测大面积地表缓慢形变的重要手段，但对流层延迟相位大大影响了形变监测的精度。以青藏高原西北缘为研究区域，分析了经验模型线性改正、通用型 InSAR 大气校正在线服务（generic atmospheric correction online service for InSAR, GACOS）改正和欧洲中期天气预报中心（European Centre for Medium-Range Weather Forecasts, ECMWF）最新发布的ERA5（ECMWF reanalysis v5） 数据集改正3种方法在时序InSAR反演形变速率中的改正效果。通过掩模技术计算非形变区的速率标准差，分析形变速率与地形的相关性，并与GPS数据进行比较分析后发现，自西向东的3个研究区域76.5°E~79.7°E（D136）、80.5°E~83.7°E（D165）、84.9°E~88.1°E（D19）范围内，其线性改正后标准差分别降低了41.05%、59.21%、25.13%，而GACOS改正后标准差分别降低了38.76%、55.97%、30.73%，ERA5改正后其标准差分别降低了10.05%、30.11%、20.15%。此外，InSAR与GPS站视线向形变速率比较显示线性改正、GACOS改正与ERA5改正后3个研究区域内其均方根误差分别降低了46.07%、51.28%和35.51%。对于青藏高原西北缘，3种方法均可削弱对流层延迟效应，其中线性改正和GACOS改正的效果好，适用性更高，ERA5受地面监测站点密度影响，在该区域改正效果稍差。

Time Series Analysis of InSAR Data: Methods and Trends

  Objectives  Time-series analysis of interferometric synthetic aperture radar (InSAR) plays an important role in monitoring large-scale surface slow deformation. However, the impact of tropospheric delay limits the accuracy of mapping deformation. Tropospheric delay correction is crucial to InSAR deformation rate inversion objective.  Methods  We focus on the northwestern margin of the Qinghai-Tibet Plateau and use three methods which are the empirical model linear correction, generic atmospheric correction online service for InSAR (GACOS) and ERA5 dataset released by the European Centre for Medium-Range Weather Forecasts (ECMWF) in the time-series InSAR inversion of deformation rate to study their applicability in this region.  Results  By calculating the standard deviation in the non-deformation region with the mask technique, analyzing the correlation between deformation rate and topography, and comparing with the GPS data, the results show that three study areas from west to east, in the range of D136 (76.5°E—79.7°E), D165 (80.5°E—83.7°E) and D19 (84.9°E—88.1°E), the standard deviations of linear corrected are decreased by 41.05%, 59.21% and 25.13%. The standard deviations of GACOS corrected are reduced by 38.76%, 55.97% and 30.73%, and those of ERA5 corrected are decreased by 10.05%, 30.11% and 20.15%, respectively. Besides, the correlation coefficients between deformation rate and elevation of the three profiles are 0.68, 0.93 and 0.60, respectively. With the increase of correlation coefficients, the advantage of linear correction becomes obvious. In addition, the comparison of LOS deformation rates between InSAR and GPS projected shows that the root mean square error of linear correction, GACOS correction and ERA5 correction in the three study areas are reduced by 46.07%, 51.28% and 35.51% respectively.  Conclusions  The northwestern margin of the Qinghai-Tibet Plateau, all three methods can mitigate tropospheric effects, and the linear correction and GACOS correction perform better and have higher applicability. While the performance of ERA5 is slightly poor due to the density of ground monitoring stations. Considering that terrain, altitude, geographical location and other factors will affect the atmospheric delay, the atmospheric correction methods and correction effects applicable to different regions need to be comprehensively studied and analyzed based on the specific situation.