摘要：Several previous Synthetic Earth Gravity Model (SEGM) simulations are based on existing information about
the Earth’s internal mass distribution. However, currently available information is insufficient to model the Earth’s
anomalous gravity field on a global scale. The low-frequency information is missing when modelling only
topography, bathymetry and crust (including the Mohoroviciˇ c discontinuity), but the inclusion of information ´
on the mantle and core does not seem to significantly improve this situation. This paper presents a method to
determine a more realistic SEGM by considering simulated 3D mass distributions within the upper mantle as a
proxy for all unmodelled masses within the Earth. The aim is to improve an initial SEGM based on forward
gravity modelling of the topography, bathymetry and crust such that the missing low-frequency information is
now included. The simulated 3D mass distribution has been derived through an interactive and iterative mass
model optimisation algorithm, which minimises geoid height differences with respect to a degree-360 spherical
harmonic expansion of the EGM2008 global external gravity field model. We present the developed optimisation
algorithm by applying it to the development of a global SEGM that gives a reasonably close fit to EGM2008, and
certainly closer than a SEGM based only on the topography, bathymetry and crust.
关键词：Synthetic Earth Gravity Model (SEGM) ;global source model ;3D mass optimisation ;forward gravity modelling
