Regional gravity field recovery of the void areas using SGG-derived surface residual gravity disturbances based on least-squares collocation: a case study in Iran

Objective of this paper is regional gravity field modelling of the Earth combining surface gravity disturbances and satellite gravity gradiometry (SGG) data based on the least-squares collocation (LSC) over the void areas in Iran, where the existing gravity data are not intensified or available. The gravity disturbances are obtained at minimum geocentric sphere, which is inside the topographic masses by joint inversion of the four high-accuracy components (Vxx, Vyy, Vzz, Vxz) of the GOCE SGG data using second derivatives of the Hotine integral. The GOCE-only global geopotential model (GGM) GO_CONS_GCF_2_TIM_R5 up to degree and order 60 is applied to reduce the effect of the omitted distant-zone, which is restored after calculation. The residual terrain model (RTM) is removed to estimate the effect of omission error of the GGM and provide mass-free space outside the boundary surface. The GOCE-based gravity disturbances at minimum geocentric sphere are continued upward on the Earth's surface based on planar approximation of the Poisson integral and subtracted from terrestrial gravity measurements to compute the residual gravity disturbances. The surface residual gravity disturbances are gridded in different cell-sizes according to the distribution of input gravity data and the locations of the empty cells that represent the void areas are determined. The height-uncorrelated residual values are applied to predict the residual gravity disturbance for every empty cell based on the LSC method using analytical local covariance function. The calculated results yielded an improvement of about 18.1% to 24.6% in gravity field recovery compared to the only RTM-corrected GGM-based solutions for two selected test areas in Iran.     «

Objective of this paper is regional gravity field modelling of the Earth combining surface gravity disturbances and satellite gravity gradiometry (SGG) data based on the least-squares collocation (LSC) over the void areas in Iran, where the existing gravity data are not intensified or available. The gravity disturbances are obtained at minimum geocentric sphere, which is inside the topographic masses by joint inversion of the four high-accuracy components (Vxx, Vyy, Vzz, Vxz) of the GOCE SGG dat...     »