Ocean tide loading correction for InSAR measurements: Comparison of different ocean tide models

With the rapid development of modern Interferometric Synthetic Aperture Radar(InSAR)missions,SAR instruments with wider coverage can be used to monitor the ground surface deformation from regional to global scale.However,the ocean tide loading(OTL)displacement is becoming a primary source of errors.It contributes to a long-wavelength signal in InSAR interferograms,leading to errors from millimeter to centimeter-level in InSAR deformation monitoring,especially over coastal areas.Although the state-of-the-art has applied ocean tide models to mitigate the errors,the difference between them and their impact on InSAR measurements are rarely discussed.In this paper,we compare representative ocean tide models and investigate their effects in the correction of OTL errors.We found that(i)the modeled OTL displacements from different models show little difference over interiors far from the ocean,while disagreement becomes larger over coastal areas;(ii)the magnitude of OTL artifacts may be greater than the atmospheric delays in some coastal areas,and the correction using ocean tide models can effectively attenuate the OTL effects for large-scale InSAR measurements;(iii)when correcting the OTL errors for InSAR measurements,the global model TPXO and FES are recommended because of their better overall performance,while the NAO model performs the worst.The local models with high spatial resolution can help improve the capability of coarse global models in complex topographic areas.