Global Isostatic Gravity Maps From Satellite Missions and Their Applications in the Lithospheric Structure Studies

Recent satellite gravity missions provide information on the Earth's gravity field with a global and homogenous coverage. These data have been utilized in geoscience studies to investigate the Earth's inner structure. In this study, we use the global gravitational models to compute and compare various isostatic gravity data. In particular, we compile global maps of the isostatic gravity disturbances by applying the Airy-Heiskanen and Pratt-Hayford isostatic theories based on assuming a local compensation mechanism. We further apply the Vening Meinesz-Moritz isostatic (flexural) model based on a more realistic assumption of the regional compensation mechanism described for the Earth's homogenous and variable crustal structure. The resulting isostatic gravity fields are used to analyze their spatial and spectral characteristics with respect to the global crustal geometry. Results reveal that each of the applied compensation model yields a distinctive spatial pattern of the isostatic gravity field with its own spectral characteristics. The Airy-Heiskanen isostatic gravity disturbances provide a very smooth gravity field with no correlation with the crustal geometry. The Pratt-Hayford isostatic gravity disturbances are spatially highly correlated with the topography on land, while the Vening-Meinesz Moritz isostatic gravity disturbances are correlated with the Moho geometry. The complete crust-stripped isostatic gravity disturbances reveal a gravitational signature of the mantle lithosphere. These general characteristics provide valuable information for selection of a particular isostatic scheme, which could be used for gravimetric interpretations, depending on a purpose of the study.