Enhancing Regularity and Accuracy of VLBI EOP Products

This study focuses on the development of a daily VLBI time series of Earth Orientation Parameters (EOP) with improved accuracy and regularity by combining data from various VLBI sessions at the normal equation level. The combined approach addresses the limitations of the existing IVS EOP products, the EOP-S and EOP-I series, which are currently estimated and published separately for 24-hour geodetic VLBI sessions and 1-hour Intensive sessions.

While the EOP-S series is characterized by high accuracy due to the observation of global networks over 24 hours, its temporal resolution is irregular and non-daily. In contrast, the EOP-I series provides daily EOP values but also has irregular temporal resolution, as it is estimated at mid-session epochs that vary depending on the type of Intensive session. Furthermore, the short observation periods of one-hour result in lower dUT1 estimation accuracy compared to the EOP-S product. By combining data from these session types, this study aims to reduce these limitations to achieve a daily and more consistent EOP series with improved accuracy.

The presentation will detail the methodology used for the combination, including session selection and the data handling process. Challenges such as data gaps, inconsistencies, and systematic effects are addressed. The results demonstrate significant improvements in both the temporal regularity and the accuracy of the resulting EOP series, enabling better comparability with other EOP products and providing robust input for EOP prediction algorithms. This work highlights the potential of intra-technique combination to enhance the quality and usability of VLBI-based geodetic products.