UT1/ΔLOD data combination method with domestic broadband VLBI2010 system and iGMAS.

Due to the lack of observation frequency of very long baseline interferometry (VLBI) in China, universal time (UT1) lacks continuity, a combination approach is proposed by combining the UT1 sequence produced by the domestic broadband VLBI system (VLBI2010) and the variation of length of day ΔLOD sequence produced by the international global navigation satellite system (GNSS) monitoring and assessment system (iGMAS). The Vondrak algorithm is used to combine the UT1 sequence of VLBI2010 and the ΔLOD sequence of iGMAS. The Markov chain Monte Carlo (MCMC) simulation is used to investigate the relationship between the combined accuracy of UT1 sequences and the input measurement accuracy and time interval, and the optimization of the weight ratio between UT1 and ΔLOD. Finally, the combined UT1 sequence is compared with the IERS 14 C04 UT1 sequence. It is shown that the combination algorithm can effectively improve the accuracy of the output UT1 series: the accuracies of 2018 and 2020 UT1 series are 32 µs and 51 µs respectively. Compared with the original series, the accuracy of the combined result is improved by more than 30%. [ABSTRACT FROM AUTHOR]