Accuracy of velocities from annually repeated GPS campaigns

The determination of GPS velocity accuracy and velocity uncertainty has been one of the topics of interest to researchers in recent years. Velocity and velocity uncertainty from continuous GPS data have been studied as deeply as possible, but velocity and velocity uncertainty from campaign measurements are still the subject of ongoing research. Recent studies have shown that the positioning accuracy of GPS PPP is latitude-dependent. At the same time, the velocity and velocity uncertainty produced by the PPP should also be treated in the same way. In this sense, it is necessary to make a global assessment. NASA JPL offers researchers a rich global database constituting GNSS time series analysis results across the globe. In this study, an experiment is conducted to determine the velocity quality of GPS campaign measurements from around 30 globally distributed stations of the IGS network. This time, our motivation is to determine the accuracy and uncertainty of GPS campaign rates from at least 4 years of data, which are performed annually on the same date. As in our previous study, we decimated coordinate components from the NASA JPL time series to generate GPS campaigns. In other words, we use 24-hour data for annual campaign measurements and repeat campaigns on three consecutive days each year. The deformation rates from NASA JPL were considered real and the accuracy of the deformation rates produced by our experiments was evaluated. Preliminary findings suggest that velocity deviations from the truth may be more severe, at 4 mm/year horizontally and 10 mm/year vertically. In the presentation, we discuss the ground truths that lead to this bias and the global distribution of velocity accuracy and velocity uncertainty.