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Ocean Tide Loading Correction for InSAR: A Case Study in Ireland

With the rapid development of Synthetic Aperture Radar (SAR) satellite missions in recent years, InSAR is moving towards large-scale deformation mapping, which may cover countries or continents. In such applications, the long-wavelength errors in the interferograms, which mainly include the atmospheric delay and the ocean tide loading (OTL) displacement, should be estimated and removed. In this work, we focus on the OTL effects that may introduce millimeter- to even centimeter-level error into the InSAR monitoring results in the coastal areas. Ocean tide models are widely used for OTL correction, while the performance of different models is rarely evaluated. In addition, in many cases the assessment of their performance has not been emphasized. In this work, the three most representative models, i.e., FES2014, TPXO9-atlas-v4 and OSU.EURPSHELF.2008, are chose to investigate their performance differences in correcting the OTL effect in Sentinel-1 interferograms covering Ireland. It turns out that (i) the OTL displacement differences of the three models are mainly in the vertical direction, with the standard deviations ranging from 0.4 to 0.6 mm; (ii) the three ocean tide models have little difference in correcting the interferograms in Ireland; (iii) the magnitude of the OTL errors could be comparable to the atmospheric delays in some cases.