A Geocenter Time Series from a Combination of LAGEOS and GRACE Observations

Abstract

The geocenter motion can be inferred by evaluating Satellite Laser Ranging (SLR) observations to the LAGEOS satellites. Within the dynamic orbit determination process the degree 1 coefficients of a spherical harmonic expansion of the Earth’s gravity field are estimated. In a combined approach covering the years 2006–2011, GRACE mission GPS, K-band inter-satellite range-rate, and SLR observations are added to the LAGEOS solution via normal equations to examine possible improvements of the geocenter estimates. The particular effects on the estimates by each of the GRACE observation types are analyzed and the combined solutions are assessed and discussed. It turns out that adding GRACE data degrades the LAGEOS geocenter time series while at the same time consuming considerable computational resources.