Meteorological and Tidal Effects on GNSS Reflected Signal in Mediterranean Coasts of Turkey

Beşel C., Tanır Kayıkçı E.

Scientific Assembly of the International Association of Geodesy (IAG), Beijing, China, 28 June - 02 July 2021, pp.1

  • Publication Type: Conference Paper / Summary Text
  • City: Beijing
  • Country: China
  • Page Numbers: pp.1
  • Karadeniz Technical University Affiliated: Yes


Sea level is a key component of climate change and plays an important role in the hydrological cycle. Rising sea levels have significant impacts such as environmental, social, and economic along with coastal areas. Global Navigation Satellite System Interferometric Reflectometry (GNSS-IR) enables to retrieve sea level heights using the reflected signal. Moreover, GNSS-IR is considered a promising alternative to conventional tide gauges. This study focuses on the determination of meteorological and tidal effects on GNSS reflected signals from the sea surface.  We used Signal-to-Noise Ratio (SNR) data from the MERS IGS (International GNSS Service) network station located on the Mediterranean coast of Turkey. Time series of SNR data were analyzed to determine sea level variations. The various meteorological parameters such as temperature, air pressure, and wind speed, which were acquired from the nearby Erdemli tide gauge operated by the Turkish National Sea Level Monitoring System (TUDES), were utilized. Furthermore, tidal harmonic analysis was applied to both MERS station and Erdemli tide gauge to calculate tidal constituents which are an important parameter for the investigation of sea level variations. For this stage, tidal constituents were used including annual constituent, semi-annual term, long-term constituents, diurnal tides, semi-diurnal tides, third-diurnal tides, sixth-diurnal tides, quarter-diurnal tides, and third-diurnal tide. We compared the tidal constituents estimated from GNSS-IR and tide gauge observations. On the other hand, SNR amplitudes were compared to meteorological and tide parameters to investigate the effect on GNSS reflected signals from the sea surface. The results of meteorological parameters have shown that as temperature increases the SNR amplitudes decrease in the Mediterranean coasts of Turkey. In tidal harmonic analysis, the annual constituent (SA) is the largest tidal constituent with an amplitude higher than 11 cm.