Continuously observed GPS data and meteorological observations spanning rainy summer from May to August and covering entire Hong Kong were processed in this paper. Zenith Total delay (ZTD) and corresponding Precipitable Water Vapor (PWV) were retrieved from above observations and validated by tropospheric product from IGS and Radiosondes observations. Differential two-way Radar Line of Sight (LOS) slant atmospheric phase map was then obtained from GPS PWV through Universal Kriging Prediction and Niell Mapping Function with azimuth asymmetry consideration. In our designed experiment, the acquired Radar atmospheric phase map was used to calibrate the 35-day interval HK ASAR Interferogram and comparatively analyze the feasibility of such mitigation. Additionally, Coherent Point (CP) targets from Radar Image were extracted to perform deterministic assessment for the improvement of atmospheric mitigation on InSAR from GPS water vapor. The result demonstrated that atmospheric mitigation from GPS PWV could reduce the InSAR residual atmospheric noise under 1cm for 88% coherent points in HK. The technique would to some extent break through the bottle neck of atmospheric de-correlation in case of small SAR image amount in hazard emergency monitoring in Hong Kong.
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