Investigation of sea level change in turkish coasts using GNSS interferometric reflectometry technique

Sea level change is well known to have environmental, economic, and social significance, especially in coastal areas. For this reason, it is extremely important to determine the sea level change. Global Navigation Satellite Systems Interferometric Reflectometry (GNSS-IR) technique enables the determination of sea level change using the reflected signals. This study consists of four parts. In the first part, suitable stations were detected from onshore and nearshore permanent GNSS stations located on different coasts of Turkey to determine sea level changes with the GNSS-IR technique. In this way, TRBZ and SNOP on the Black Sea from co-located GNSS station, MERS station on the Mediterranean coasts from IGS network, and TEKR on the Marmara from the TUSAGA-Active were determined to be suitable for the aim of the study. The sea level changes were retrieved using the signal-to-noise ratio (SNR) data of these stations by the GNSS-IR technique. The GNSS-IR-based sea level changes were then compared to sea level records from nearby tide gauges or co-located tide gauges. In the second part, quality control was performed using three different methods to improve the performance of the GNSS-IR technique in detecting sea level changes. The best performance was mostly obtained from the LSP-MA method. In the third part, the effect of the meteorological conditions was examined on the reflected GNSS signal. In the fourth part, the determination of tidal constituents, an important parameter of sea level change, was investigated with the GNSS-IR technique in our country. It is thought that GNSS-IR techniques may also have the potential to estimate tidal constituents. Consequently, it is demonstrated that significant contributions can be made to national/international studies in the determination of GNSS-IR-based sea level change using onshore and/or nearshore permanent GNSS stations in our country and improvement of the performance of the technique.