Analysis of Accuracy in Velocity Components Derived from Global Navigation Satellite Systems (GNSS) Campaign Measurements

---

Thesis Type: Postgraduate

Institution Of The Thesis: Yıldız Technical University, Graduate School of Natural and Applied Sciences, HARİTA MÜHENDİSLİĞİ ANABİLİM DALI, Turkey

Approval Date: 2023

Thesis Language: Turkish

Student: Ece Uysal

Supervisor: Doğan Uğur Şanlı

Open Archive Collection: AVESIS Open Access Collection

Abstract:

Although regular time series derived from continuous observation GNSS station data are more useful in determining station velocities and deformations, it is not possible to abandon campaign measurements. For this reason, efforts to improve the deformation determination results obtained from campaign measurements continue. In this study, the accuracy of velocity parameters calculated by using daily time series produced by PPP for IGS stations by using GPS observations by NASA Jet Propulsion Laboratory (JPL) was investigated. Within the scope of the study, 31 homogeneously distributed IGS stations were selected in line with the Central Limit Theorem (minimum 30 points) and the stations were classified as regional. 4 years of continuous GPS data from 2016-2019 were used. Campaign measurements were sampled on a regular basis, once a year, for 3 consecutive days. Campaign time series are generated from continuous data of JPL. Data free of geomagnetic storms were used. In this direction, 24, 25, 26 May dates were deemed appropriate. The annual seasonal effect was taken into account by eliminating inconsistent measures. As a result of the velocity estimation, a difference of 1 mm/yr was observed in the horizontal component between the continuous GPS and the campaign velocities. This difference is up to 8 mm/yr in the vertical component. There was no significant difference between the velocities generated from campaign measurements and the velocities generated from continuous GPS, with a 95% confidence level. In the campaign measurements, the velocity estimation error was treated as colored noise. As a result, an accuracy of 1 mm/yr horizontally and 3 mm/yr vertically was obtained. Regional differences in velocity errors were observed. In the results obtained from the campaign time series, accuracy loss of 0.1- 0.3 mm/year in the horizontal components and 0.5-1.5 mm/year in the vertical component was detected in the combinations of WN (white noise), WN+FN (flicker noise), WN+RWN (random walk noise), WN+FN+RWN, which were created according to the noise types. Within the scope of this study, when compared to studies that measure campaigns once a year, it is seen that vertical accuracy is approximately 3 times better. It will be possible to obtain more precise results when the sampling interval of the campaign time series is kept longer than the continuous time series.