Research Information System
4th INTERNATIONAL SYMPOSIUM OF SCIENTIFIC RESEARCH AND INNOVATIVE STUDIES (ISSRIS'24), Balıkesir, Turkey, 13 March - 16 April 2024, pp.591-592, (Summary Text)
The gravity field of the Earth contains various information about the shape and physical structure of the Earth. By using temporal changes in the gravity field, it is possible to obtain various geopotential changes such as gravity anomaly changes, changes in sea surface, hydrological changes, and water-induced land movements. This variation in the field has been globally monitored since 2002 through the Gravity Recovery and Climate Experiment (GRACE) satellite mission. GRACE is highly sensitive to hydrological changes, allowing for the detection of changes in continental water budgets, ocean floor changes, and amounts of melting ice with high precision.
The Global Positioning System (GPS), on the other hand, enables us to track both horizontal and vertical movements of points on the Earth's surface at the millimeter level. In this study, vertical displacement time series from certain fixed GPS stations distributed throughout Turkey were compared with vertical displacement time series derived from GRACE harmonic models related to these points. The amplitude of the annual change signal obtained from both GRACE and GPS time series was found to be similar at many points. The amplitude of the annual change signal derived from GPS was calculated to be in the range of 1.66 and 6.83 mm with a mean amplitude of 3.79 mm, while the amplitude of the annual change signal derived from GRACE was calculated to be in the range of 2.03 and 4.29 mm with a mean amplitude of 3.45 mm. The GPS annual signal was obtained approximately 3 months delayed compared to the GRACE signal. This result indicates that the water change at many points leads to a terrestrial movement on the physical Earth's surface after a delay of 3 months. In other words, the GPS signal responds to water changes with such a delay depending on the morphological characteristics of the location.