Assessment of the Recently Released GOCE-Based Models in Terms of Spectral and Spatial Resolution

Abstract

Recently, many global geopotential models (GGMs) were computed and released based on data collected by the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission. Based on different computational approaches and different observations in terms of quantity and quality, the final product is a set of spherical harmonic coefficients representing the series expansion of the gravitational potential up to a certain maximum degree and order. In order to quantify and assess the features of these global gravity models, we perform a quality assessment both in an absolute and relative sense with respect to other similar models or some reference Earth gravity models. In this comparative analysis the so-called topographic/isostatic gravity models, which represent the contribution of global digital elevation maps for topography and ocean bathymetry to the gravity spectrum, have been included as well. Applying a range of available spatial and spectral accuracy and assessment measures, it becomes obvious that GOCE data contribute to the medium wavelength from degree and order 100 up to degree and order 200. The difference variances of the new released GOCE-based models with respect to the state-of-the-art model EGM2008 at the spectral bandwidth 100 to 200 and the spectral correlation among GOCE-models and EGM2008 up to degree and order 200 lead to the conclusion of an improvement in gravity field representation from the new GOCE models. This conclusion is enhanced with a statistical spatial analysis in regions, such as South America, Antarctica, Central Asia and Africa, where the differences among GOCE models and EGM2008 are large due to the lack of terrestrial data for the computation of the latter.