ITG-Grace02s: A Grace gravity field derived from range measurements of short arcs

Abstract

Three years of GRACE data have been used to simultaneously determine the static gravity field model ITG-Grace02s up to a maximum spherical harmonic degree of n=160 as well as monthly variations in the long wavelength part in one recovery step. The physical model of the gravity field recovery technique is based on Newton’s equation of motion, formulated as a boundary value problem in the form of a Fredholm type integral equation. The principal characteristic of this method is the use of short arcs of the satellite's orbit in order to avoid the accumulation of modelling errors and a rigorous consideration of correlations between the range observations in the subsequent adjustment procedure. Only the results of the static gravity field model are presented here. The validation of the gravity field model is performed by comparisons with existing GRACE satellite-only and combined gravity field models as well as by external validation based on different data sets. The results reveal the excellent quality of the presented gravity field model.