1″与3″SRTM DEM在珠江三角洲地区InSAR形变监测中的应用效果比较

A Comparison of 1″ and 3″ SRTM DEM on InSAR Deformation Monitoring in the Pearl River Delta

2014年9月,美国逐步向全球用户免费开放了1″(约30 m)分辨率的SRTM DEM(Shuttle Radar Topography Mission Digital Elevation Model)数据.为了比较其与之前发布的3″(约90 m)分辨率SRTM DEM数据对InSAR(Interferometric Synthetic Aperture Radar)形变监测结果的差异,本文采用欧空局Envisat卫星的雷达影像,分析这两种不同分辨率的DEM对珠江三角洲地区单个干涉图和多个干涉图获得的平均速率的差异.研究结果显示:1″与3″DEM对单个干涉图形变量结果的差异与基线长度有关,以垂直基线长度为50 m的干涉图为例,其差值分布在±4 mm之间,其中89%介于±1 mm;由于多个干涉图的垂直基线随机分布,DEM对于整个轨道多干涉图获得的平均速率影响分布在±4 mm/a之间,其中90%介于±1 mm/a;差异明显的区域主要在地形起伏较大的山区.因此,本文认为1″与3″SRTM DEM对珠三角地区InSAR形变监测结果的差异并不显著.

The United States gradually released the1″(about30m)SRTM DEM(Shuttle Radar Topography Mission Digital Elevation Model)data to global users in September2014.To compare the difference between1″and previously released3″(about90m)SRTM DEM data on InSAR(Interferometric Synthetic Aperture Radar),interferograms are produced by using radar images from the European Space Agency's(ESA)Envisat and the influence of different DEM on the single interferogram and the average velocity of multiple interferograms covering the Pearl River Delta region analyzed.The results show that the difference between1″and3″DEM on the single interferogram is proportional to the length of the perpendicular baseline.For an interferometric pair with perpendicular baseline of50m,for example,the difference is distributed within±4mm,and89%of which is within±1mm.Due to the random distribution of the perpendicular baselines for multiple interferograms in a track,the difference of the average rate obtained from all the interferograms is within±4mm/yr,and90%of which is within±1mm/yr.Therefore,it is concluded that1″and3″SRTM DEM have no significant difference on InSAR deformation monitoring in the Pearl River Delta.