GIA-induced Geopotential Variation Constrained By Gnss Vertical Deformation Observation

Besides studies on sea level change and mantle rheology,reliable Glacial Isostatic Adjustment?GIA?models are necessary as a background model to correct the widely used GRACE monthly gravity solutions.While most studies on the GIA-induced geopotential change are on the basis of the approximate theory of Wahr et al.^[1-2],Purcell et al.^[3],Jia et al^[4]pointed out that this method will lead to a¹5%relative error,which would weaken GRACE's monitoring of global changes.In this study,the accurate relationship between GIA vertical surface deformation and gravitational potential changes proposed by Purcell et al.^[3]is used to improve the GIA-induced geopotential change using GNSS vertical deformation observation,which may serve as a GIA-correction model for GRACE time-variable gravity data.Besides studies of sea level change and mantle rheology,reliable Glacial Isostatic Adjustment?GIA?models are necessary as a background model to correct the widely used GRACE?Gravity Recovery and Climate Experiment?monthly gravity solutions to determine sub-secular,non-viscous variations.Based on spherical harmonic analyses,we developed a method using degree-dependent weighting to assimilate GPS?Global Positioning System?derived crustal uplift rates into GIA model predictions,via which the good global pattern of GIA model predictions and better local resolution of GPS solutions are both retained.Some systematic errors in global GPS uplift rates were also corrected during that spherical harmonic analyses.Further,we used the refined GIA uplift rates to infer the GIA-induced rates of Stokes coefficients relying on the accurate relationship between GIA vertical surface deformation and gravitational potential changes.The results may serve as a GIA-correction model for GRACE time-variable gravity data.