Simulated Analysis of EOP Measurement Accuracies with Participation of Chinese VGOS Stations in International Observations

Objectives Very long baseline interferometry (VLBI) is one of the main space geodetic techniques for monitoring Earth orientation parameters (EOP). China is building three VLBI global observing system (VGOS) antennas. In order to improve the EOP measurement accuracies, it is necessary to optimize VGOS observing network by extending the domestic VGOS network to an international network.

Methods We set three Chinese VGOS stations located at Shanghai, Urumqi and Beijing as core stations, by adding two international stations selected from four candidate sites located at Hobart of Australia or Bandung of Indonesia, as well as Johannesburg of South Africa or Hawaii of USA, we could form four different 5-station VGOS networks. The performance of EOP measurement accuracies for each network were analyzed based on generation of bulk observing schedules and subsequent large-scale Monte Carlo simulations. We used the repeatability value defined as standard deviation of EOP estimates as an indicator to evaluate the performance of each schedule and each network. We also compared the EOP formal errors of current VGOS observing sessions to our simulation results.

Results The experiment results show that: (1) The EOP measurement capability of the expanded 5-station networks are all much better than that of the 3-station domestic network. (2) The optimized 5-station network, which consists of 3 domestic antennas, Johannesburg in South Africa and Hobart in Australia, has the best EOP measurement results. Compared to the 3-station domestic network, the repeatability of dUT1, the pole motion X_P and Y_P components are decreased by a factor of 5.7, 2.8 and 18.3, respectively. (3) The optimized 5-station network could reach equal or even better EOP estimates than that of the current IVS VGOS observing networks. We demonstrated that the EOP measurement accuracies can be improved by optimizing the observing network based on Monte Carlo simulations.

Conclusions The simulation results can be served as a start point for the future development of high-precision EOP observing program in China.