MAPPING SMALL ELEVATION CHANGES OVER LARGE AREAS - DIFFERENTIAL RADAR INTERFEROMETRY
MAPPING SMALL ELEVATION CHANGES OVER LARGE AREAS - DIFFERENTIAL RADAR INTERFEROMETRY
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DOI：
10.1029/jb094ib07p09183
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发表时间：
1989-07-10
期刊：
影响因子：
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通讯作者：
ZEBKER, HA
中科院分区：
文献类型：
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作者：
GABRIEL, AK;GOLDSTEIN, RM;ZEBKER, HA
一种技术，使用合成孔径雷达（SAR）图像测量非常小的（1厘米或以下）的表面运动，具有良好的分辨率（10米）在大的扫描带（50公里）的沿着与实验结果。该方法可用于精确测量许多地球物理现象，包括断层带的膨胀和屈曲、地震事件的残余位移和火山前膨胀。该方法是基于合成孔径雷达干涉测量，其中两个图像是由一个场景同时飞行两个物理上分离的天线。然后对相应像元的相位进行差分，通过一些简单的计算和图像校正，推导出高度形成。也有可能使用一个天线在同一场景上空飞行两次;然后，如果第二次飞行完全复制了第一次飞行的轨迹，则会发生有趣的可能性。图像之间根本不会有相位变化，除非场景中有物理变化，如地面隆起，这将改变从某些分辨率元件到天线的距离。由于相位变化都发生在短载波波长处，所以对灵敏度的基本限制仅是系统中的相位噪声。当两次成像是从分离的飞行轨迹进行时（这里使用的海洋卫星图像就是这种情况），就不再可能区分表面变化和地形造成的视差。然而，通过一些额外的计算，可以使用在其他基线处制作的第三图像来去除形貌并且仅留下表面变化。该方法使用Seasat数据应用于加州Imperial Valley的成像站点，在那里观察到归因于吸水粘土膨胀的运动效应。显示了该区域的相变图像，沿着了关于水存在的相关地面实况。该技术的问题进行了探讨，沿着讨论未来的实验可能性即将到来的SAR任务，如地球观测系统（EOS），地球资源卫星（ERS 1），SIR-C，和金星成像雷达，麦哲伦。
A technique that uses synthetic aperture radar (SAR) images to measure very small (1 cm or less) surface motions with good resolution (10 m) over large swaths (50 km) is presented along with experimental results. The method could be used for accurate measurements of many geophysical phenomena, including swelling and buckling in fault zones, residual displacements from seismic events, and prevolcanic swelling. The method is based on SAR interferometry, where two images are made of a scene by simultaneously flying two physically separated antennas. Then the phases of corresponding pixels are differenced, and altitude formation is deduced from some simple computation and image rectification. It is also possible to use one antenna flown twice over the same scene; then, if the second flight exactly duplicates the track of the first, an interesting possibility occurs. There would be no phase changes between the images at all unless there was a physical change in the scene, such as ground swelling, that would alter the distance from some resolution element to the antenna. Since the phase changes all occur at the short carrier wavelength, the basic limitation on sensitivity is only the phase noise in the system. When the two imaging passes are made from flight tracks that are separated (which is the case with the Seasat images used here), it is no longer possible to distinguish surface changes from the parallax caused by topography. However, with some additional computation, a third image made at some other baseline may be used to remove the topography and leave only the surface changes. This method was applied using Seasat data to an imaging site in Imperial Valley, California, where motion effects were observed that were ascribed to the expansion of water‐absorbing clays. Phase change images of this area are shown, along with associated ground truth about the presence of water. Problems with the technique are explored, along with a discussion of future experimental possibilities on upcoming SAR missions like Earth Observing System (EOS), Earth Resources Satellite (ERS 1), SIR‐C, and the Venus imaging radar, Magellan.