A spatially variable power law tropospheric correction technique for InSAR data
A spatially variable power law tropospheric correction technique for InSAR data
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DOI：
10.1002/2014jb011558
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发表时间：
2015-02-01
影响因子：
3.9
通讯作者：
Wright, T. J.
中科院分区：
文献类型：
--
作者：
Bekaert, D. P. S.;Hooper, A.;Wright, T. J.
通过对流层传播的微波信号会受到延迟。这些延迟主要通过对流层下部压力、温度和相对湿度的空间和时间变化来描述，从而导致干涉合成孔径雷达（InSAR）中的对流层信号空间变化。对流层校正技术依赖于外部数据，通常受到空间和时间精度的限制，或者可以根据高分辨率干涉相位本身进行估计。然而，当前的相位估计校正技术没有考虑对流层特性的空间变化，并且无法捕获更大区域的对流层信号。在这里，我们提出并测试了一种新颖的幂律校正方法，该方法可以解释大气特性的空间变化，并且可以应用于包含地形相关变形的干涉图。幂律模型的参考点固定在对流层的相对顶部，并通过幂律关系描述相位延迟如何随高度变化。我们发现幂律模型减少了局部对流层信号（墨西哥每公里海拔平均减少约 0.45 厘米）和长波长分量，从而改善了对独立全球导航卫星系统数据的拟合。幂律模型可以应用于存在变形的情况、不同时间段和不同大气条件下，从而允许利用 InSAR 检测较小幅度的地壳变形信号。
Microwave signals traveling through the troposphere are subject to delays. These delays are mainly described by spatial and temporal variations in pressure, temperature, and relative humidity in the lower part of the troposphere, resulting in a spatially varying tropospheric signal in interferometric synthetic aperture radar (InSAR). Tropospheric correction techniques rely either on external data, often limited by spatial and temporal accuracy or can be estimated from the high-resolution interferometric phase itself. However, current phase-estimated correction techniques do not account for the spatial variability of the tropospheric properties and fail to capture tropospheric signals over larger regions. Here we propose and test a novel power law correction method that accounts for spatial variability in atmospheric properties and can be applied to interferograms containing topographically correlated deformation. The power law model has its reference fixed at the relative top of the troposphere and describes, through a power law relationship, how the phase delay varies with altitude. We find the power law model reduces tropospheric signals both locally (on average by approximate to 0.45cm for each kilometer of elevation in Mexico) and the long-wavelength components, leading to an improved fit to independent Global Navigation Satellite Systems data. The power law model can be applied in presence of deformation, over a range of different time periods and in different atmospheric conditions, and thus permits the detection of smaller-magnitude crustal deformation signals with InSAR.