On comparison of the Earth orientation parameters obtained from different VLBI networks and observing programs

TL;DR

This study introduces a new geometry index, the network volume, to evaluate how VLBI network size influences the accuracy and precision of Earth orientation parameters, revealing a power-law relationship.

Contribution

It presents the volume of VLBI networks as a new indicator for EOP error analysis and demonstrates the power-law dependence of EOP errors on network size and data rate.

Findings

EOP errors decrease with increasing network volume following a power law.

EOP accuracy is primarily influenced by network geometry, less by recording mode or data rate.

EOP precision is more affected by recording data rate and scheduling parameters.

Abstract

In this paper, a new geometry index of Very Long Baseline Interferometry (VLBI) observing networks, the volume of network $V$, is examined as an indicator of the errors in the Earth orientation parameters (EOP) obtained from VLBI observations. It has been shown that both EOP precision and accuracy can be well described by the power law $\sigma=aV^c$ in a wide range of the network size from domestic to global VLBI networks. In other words, as the network volume grows, the EOP errors become smaller following a power law. This should be taken into account for a proper comparison of EOP estimates obtained from different VLBI networks. Thus performing correct EOP comparison allows us to accurately investigate finer factors affecting the EOP errors. In particular, it was found that the dependence of the EOP precision and accuracy on the recording data rate can also be described by a power law. One important conclusion is that the EOP accuracy depends primarily on the network geometry and to lesser extent on other factors, such as recording mode and data rate and scheduling parameters, whereas these factors have stronger impact on the EOP precision.