Estimation of precipitable water vapour by GNSS meteorology in Black Sea region of Türkiye

This study investigates the estimation of precipitable water vapour (PWV) using Global Navigation Satellite System (GNSS) meteorology in the Black Sea region of T & uuml;rkiye, an area characterized by high rainfall and significant climatic variability. GNSS observations from four permanent stations (SAME, SOMU, MACK, and TRAB) between October 2017 and December 2019 were processed with Bernese 5.2 software to retrieve zenith total delay and derive PWV. The Vienna Mapping Function 1 (VMF1) was applied with a 10 degrees elevation cut-off angle, and orography-dependent pressure and temperature fields were used for tropospheric modeling. The results were compared with radiosonde measurements from Samsun station and ERA-Interim reanalysis data to assess reliability. Findings show that GNSS-derived PWV varied between 1 and 46 mm, with strong seasonal and diurnal cycles higher in summer and daytime, and lower in winter and nighttime. Radiosonde PWV exhibited strong correlation with GNSS PWV (r > 0.9), while ERA-Interim tended to overestimate values, particularly at higher elevation sites. GNSS PWV demonstrated a strong positive correlation with surface temperature (similar to 0.8) and an inverse relationship with atmospheric pressure. These results confirm the potential of GNSS meteorology as a reliable tool for continuous and high-resolution monitoring of atmospheric water vapour, supporting weather forecasting and climate studies in the Black Sea region.