Consistent celestial and terrestrial reference frames by improved modelling and combination
Final Report Abstract
The key motivation of this project was driven by the current products for the International Terrestrial Reference Frame (ITRF), the International Celestial Reference Frame (ICRF) and the EOP are not fully consistent (i.e., they are computed separately by the responsible IERS Product Centers) and that there are several deficits concerning the computation of these products. The quality and accuracy of the results is limited by various factors such as deficits regarding the geophysical background models and the handling of non-linear station motions as well as inadequate combination processes that do not allow for a consistent and reliable estimation of the geodetic reference frames. Thus, the major goal of the project was to deliver a quasi-inertial reference frame realized by quasar positions, a terrestrial reference frame and the full set of Earth Orientation Parameters (EOP) which are consistent with each other, based on a common set of parameters and in particular on homogeneous geophysical fluid models. In order to improve the combination approaches and methods for the computation of reference frames the project focuses on various aspects. BKG investigated the differences between the geophysical fluid models and their impact on the reference frame results. BKG and DGFI-TUM developed improved methods for handling non-linear station motions by applying different methods at the observation and normal equation level: (1) by correcting for non-tidal loading deformations by using geophysical models for atmosphere, oceans or hydrology; (2) by applying more sophisticated parameterization for station position variations (e.g., for seasonal signals) for the computation of long-term reference frames; (3) by computing epoch reference frames based on the weekly combination of GNSS, VLBI and SLR observations. The reference frame computations were performed on the basis of homogeneously reprocessed observation time series using the improved modelling. Based on these input data a first simultaneous estimation of the CRF, TRF and EOP was computed at DGFI-TUM. Furthermore, BKG developed combination strategies for using satellite co-locations on board GNSS satellites and demonstrated the advantages of such a new approach.
Publications
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(2013): Impact of loading displacements on SLR- derived parameters and on the consistency between GNSS and SLR results. J Geod 87(8):751-769
Sośnica K., D. Thaller, R. Dach, A. Jäggi, G. Beutler
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(2014): Consistent adjustment of combined terrestrial and celestial reference frames. In Rizos C., Willis P. (Eds.) Earth on the Edge: Science for a Sustainable Planet, IAG Symposia 139
Seitz M., P. Steigenberger, T. Artz
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(2014): Geophysical fluid models for atmosphere, ocean and hydrology and their impact on SLR analysis. In: Proceedings of the 18th International Workshop on Laser Ranging, Fujiyoshida, Japan, November 11-15, 2013
Roggenbuck, O., D. Thaller, M. Mareyen
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(2014): Non-linear station motions in epoch and multi-year reference frames. J Geod 88(1): 45-63
Bloßfeld M., M. Seitz, D. Angermann
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(2015): Loading-induced deformation due to atmosphere, ocean and hydrology: Model comparisons and the impact on global SLR, VLBI and GNSS solutions. In: van Dam T. (ed) REFAG2014. IAG Symposia Series, Vol. 146, pp. 71-77
Roggenbuck O., D. Thaller, G. Engelhard, S. Franke, R. Dach, P. Steigenberger
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(2015): Pre-combined GNSS-SLR solutions: What could be the benefit for the ITRF? In: van Dam T. (ed) REFAG2014. IAG Symposia Series, Vol. 146, pp. 85-94
Thaller D., K. Sośnica, P. Steigenberger, O. Roggenbuck, R. Dach
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(2015): Satellite laser ranging to GPS and GLONASS. J Geod 89(7), pp. 725-743
Sośnica, K., D. Thaller, R. Dach, P. Steigenberger, G. Beutler, D. Arnold, A. Jäggi
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The key role of Satellite Laser Ranging towards the integrated estimation of geometry, rotation and gravitational field of the Earth. Dissertation, Technische Universität München, Reihe C der Deutschen Geodätischen Kommission (ISBN: 978-3-7696-5157-7), 2015
Bloßfeld M.
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(2016): Epoch reference frames as short-term realizations of the ITRS - Datum stability versus sampling, In Rizos C., Willis P. (EDS.) IAG Symposia 143, 26-32
Bloßfeld M., M. Seitz, D. Angermann
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(2018), Consistent realization of celestial and terrestrial reference frames, J. Geod.
Kwak Y., R. Schmid, M. Bloßfeld,D. Angermann, M. Gerstl, M. Seitz
