High-Frequency Determination of the Earth Orientation Parameters by GNSS (GNSS-EOP)
Over the upcoming years the GNSS will be extended with the European Galileo system. It is planned to launch the complete 27-30 satellites system until 2018/19. It has been shown that GNSS provide a major observation technique for the determination of polar motion and LOD (rates of UT1-UTC), but can also contribute to the estimation of short term nutations [ROTHACHER 1999], [WEBER 2001]. This study aims to investigate the potential of Galileo to provide an added-value (in addition to GPS and GLONASS) for high-rate EOP (polar motion + LOD) and nutation offset estimation. The exact knowledge of the Earth orientation in space is an essential prerequisite for all space missions while the EOPs are a high quality data source for studying the Earth’s interior. Although this proposal focuses on Earth Rotation major tasks are also related to GNSS satellite orbit modelling (in special modelling of solar radiation pressure) as precise and long term stable GNSS orbits are an indispensable prerequisite for deriving high accuracy Earth Rotation parameters.
The main goals of this project are:
· Identify the optimum force field in order to establish precise GNSS satellite orbits (including Galileo satellites). Special focus is laid on the applied solar radiation pressure model.
· Estimation of hourly polar motion and LOD time series as well as daily nutation rate time series from GNSS observations over a period of 3 years.
· Recover the amplitudes of sub-diurnal and diurnal tidal waves.
· Recover the nutation wave amplitudes for short periods up to 30 days from the 3 years test series and compare resulting waves with the current IAU model.
· Evaluate the impact of future Galileo observations on nutation rates and how orbit deficiencies map into nutation rates (simulation).
· Recomputation of the geodetic excitation functions from GNSS and VLBI observations.
· Extraction of diurnal/semidiurnal signals from GNSS based excitation and a comparison to those derived from geophysical model and VLBI
· •Comparison of high-frequency signal from GNSS with conventional models and VLBI results.
- Europäische Weltraumorganisation ESA
- Institute for Space Research of the Polish Academy of Sciences