Heterogeneous InSAR Tropospheric Correction Based on Local Texture Correlation

Tropospheric delays have been a major limitation on the precision and accuracy of interferometric synthetic aperture radar (InSAR). InSAR phase-based tropospheric correction methods, especially the local window methods, could estimate heterogeneous tropospheric delays in the same resolution as InSAR data, thus, are increasingly desired for modern high-resolution InSAR products. However, the tropospheric phase-elevation relationship estimation at local windows can be severely contaminated by topography-correlated deformation. In this article, we present a new InSAR phase-based tropospheric correction method based on texture correlation between tropospheric delays and topography, which is shown to be relatively insensitive to topography-correlated deformation. The texture information represents the spatially high-frequency component of a 2-D image, which can be obtained using high-pass filtering. The method first produces a low-resolution tropospheric delay estimation using the window-wised texture correlation in the space domain, then refines it to high resolution by fitting the residual with the previously estimated tropospheric phase-elevation slope in the time domain. We apply the proposed method to ALOS-2 data over the Kirishima volcanic complex in Japan, encompassing typical topography-correlated deformation. The estimated phase-elevation slope shows seasonal oscillation in agreement with independent ERA5 prediction. The proposed method reduces the median spatial standard deviation (STD) of the residual phase from 0.7 to 0.4 cm, showing superior performance compared with other existing methods without compromising the deformation signal.