Abstract
Earth’s surface deformation can be measured at millimeter level using continuous Global Positioning System (GPS) data. Periodic signals, mostly annual and semiannual, originating from geophysical, environmental, and instrumental processes can be determined in these time series. Improving geodetic products, fine-tuning tectonic velocity estimates and expanding knowledge of Earth’s system mass redistribution all rely on the accurate identification and interpretation of these seasonal signals. This article analyzes the annual seasonal signal amplitude of GNSS stations located in the Western part of Romania from two different CORS networks, one of which is for monitoring the tectonic movement. The results show that the annual seasonal signal of the East component exhibits an increase of three to four times the amplitude compared to the North component, whereas the Up component shows an increase between three to four times higher than the East component.