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The development and values of the new absolute phase center correction model for global positioning system (GPS) receiver and satellite antennas as adopted by the International GNSS Service are presented. Fixing absolute receiver antenna phase center corrections to robot-based calibrations, the GeoForschungsZentrum Potsdam and the Technische Universität München reprocessed more than 10 years of GPS data in order to generate a consistent set of nadir-dependent phase center variations (PCVs) and offsets in z-direction pointing toward the Earth for all GPS satellites in orbit during that period. The agreement between the two solutions estimated by independent software packages is better than 1 mm for the PCVs and about 4 cm for the z-offsets. In addition, the long time series facilitates the study of correlations of the satellite antenna corrections with several other parameters such as the global terrestrial scale or the orientation of the orbital planes with respect to the Sun. Finally, completely reprocessed GPS solutions using different phase center correction models demonstrate the benefits from switching from relative to absolute antenna phase center corrections. For example, tropospheric zenith delay biases between GPS and very long baseline interferometry, as well as the drift of the terrestrial scale, are reduced and the orbit consistency is improved.

[1] Dual frequency GPS observables only allow the elimination of the 1st -order ionospheric term. Although higher -order ionospheric terms may cause a range bias of several centimeters, accounting for such effects is not yet a common strategy for GPS data analysis. In comparison to previous investigations a rigorous application of 2nd and 3rd -order ionospheric corrections is examined for the estimation not only of receiver positions but of all included parameters. The results reveal a linear dependence of the frame's origin on the integrated electron density. Furthermore, satellite positions are affected at the centimeter level when applying the above -mentioned corrections. Since the ionospheric correction terms show a significant impact on various GPS estimates, their consideration becomes necessary for scientific applications. Hence, the modeling of 2nd and 3rd -order ionospheric correction terms is part of the optimized strategy in an ongoing reprocessing project dealing with a global GPS network and spanning the time period from 1994 up to present time. Citation: Fritsche, M., R.

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