Combining VLBI and ring laser observations for determination of high frequency Earth rotation variation

Data from the Wettzell ring laser gyroscope are combined with Very Long Baseline Interferometry observations in order to estimate polar motion and Universal Time with hourly resolution. The combination is done at the normal equation level. Data from the period 1 May to 14 October, 2010, are used. We find that the impact of the ring laser data is normally relatively small since presently the accuracy of VLBI is about one order of magnitude better than the accuracy of the ring laser measurements. However, in cases when the accuracy of VLBI is of the order of 1 mas or worse the ring laser improves the accuracy of the estimated parameters, especially for y-pole and Universal Time. For the whole period, the combination on average improves y-pole by 16% and Universal Time by 12% compared to when using only VLBI data.