A novel tidal model for long-strip DInSAR measurement by integrating tidal constituent estimation of the GPS network and empirical models

A long-strip synthetic aperture radar interferometric (InSAR) measurement based on multiframe image mosaicking is currently the realizable approach to measure large-range ground deformation. As the spatial range of the mosaicked images increases, the degree of ground effects are more significant, and using empirical global ocean tidal models or plane fitting to correct the OTL displacement will produce large errors in a region with a complex coastline. By integrating the Q1, O1, N2, and M2 constituents of a GPS reference station network and the P1, K1, and K2 constituents of an empirical global/regional ocean tidal model, thethree-dimensional OTL displacements for high-precision DInSAR measurement is calculated, which can improve the accuracy of the OTL correction along the LOS direction by 10.4% in a complex coastline area. Meanwhile, the proposed OTL correction methodand a solid earth tide (SET) model areused to estimate the ground tidaldisplacements in coastal long-strip differential interferograms. Experimental results show that the ground tidal displacementscan reach 77.5 mm. If the bilinear ramp fitting method is used in a coastal long-strip interferogram, the residual of the tidal displacement is up to 20.3 mm, the novel OTL correction methodand SET model can minimize the standard deviation (StdDev) of a differential interferogram by 19.3%, itsmajor improvement region is the coastal area where the OTL displacement is more than 10~17 mmandthe tendency of tidal displacement in long-strip interferogramscanbeaccurately eliminated, which proves that the novel tidal methodcorrectionhashigh spatial accuracy.