The IfE global gravity field model from GOCE-only observations
19/09/2016 | 17:15 | Session 2: Global gravity field modelling
Author(s): Hu Wu, Jürgen Müller and Phillip Brieden
Hu Wu, Jürgen Müller and Phillip Brieden
GOCE (Gravity field and steady-state Ocean Circulation Explorer) was the first satellite mission which combined SST-hl (Satellite-to-Satellite high-low) and SGG (Satellite Gravity Gradiometry) techniques to measure the Earth’s gravity field. During its lifetime, between 2009 and 2013, it delivered hundreds of millions of measurements. ESA published these observations so that the worldwide users can work with them in their scientific fields. In this study, we will present our latest GOCE-only global gravity field model, which is obtained from our own IfE software package.
To recover such a gravity field model, the SST-hl and SGG observations are analyzed both separately and jointly. The SST-hl observations are processed with the acceleration approach which balances the satellite accelerations with the first-order derivatives of the gravitational potential, while the SGG observations are directly balanced with the second-order derivatives of the gravitational potential. The separate analysis of the two types of observations leads to two models that are accurate at complementary wavelengths, and the joint analysis by the VCE (Variance Component Estimation) approach gives the final model with high accuracy over the full spectrum up to a certain spherical harmonic degree.
All the four years’ observations (from November 2009 to October 2013) are used for our latest solution, which is named as IfE_Goce05s. This gravity field model has a resolution with a maximum degree and order of 250, i.e. 62,997 unknown spherical harmonic coefficients had to be estimated. The performance of IfE_Goce05s is then evaluated, showing an excellent agreement with the official GOCE models.