Monday 22 August 2005

G4
1330-1500 hours

060
Advances in terrestrial reference frame computations
Angermann, Detlef¹, Drews, Hermann¹, Kruegel, Manuela¹, Meisel, Barbara¹
1 Deutsches Geodaetisches Forschungsinstitut, Munich, Germany
Author email: kruegel@dgfi.badw.de
Space geodetic techniques allow to determine geodetic parameters (e.g., station positions, Earth orientation) with an accuracy up to the millimeter level. However, this high accuracy is not fully reflected in current realizations of the terrestrial reference frame (TRF), such as ITRF2000. Major deficiencies are still remaining biases between different techniques and non- linear station motions which are not considered in past TRF realizations including positions at a reference epoch and constant velocities only. In its function as an ITRS Combination Center, DGFI has developed refined combination methods for the TRF computation (Angermann et al. 2004, Meisel et al., 2005). The advanced approach is based on the combination of epoch normal equations (weekly/ daily data sets) containing station positions and Earth orientation parameters (EOP) obtained from different geodetic space techniques (VLBI, SLR, GPS and DORIS). The time series of station positions and EOPs were analysed and compared between techniques to identify common signals and remaining technique-specific problems. This refined approach allows to account for all non-linear effects (e.g., periodic signals and discontinuities) in station position and datum parameters and to ensure consistency between TRF and EOPs. Another advantage is that the EOPs can be used to validate the local tie selection and theystabilize the inter-technique combination as additional 'global' ties. Kinematic models such as APKIM2004 are used for the realization of the TRF kinematic datum and the results are compared with those obtained with the geophysical NNR-NUVEL-1A model. The ITRF2004 submissions were used as input data. Results for a refined terrestrial reference frame computation are presented. References: Angermann et al. 2004, DGK, Reihe B, Heft Nr. 313. Meisel et al. 2005, Proc. COSPAR 2004, Adv. Space Res., Elevier.

Return to Oral Presentations