Assessment of precipitable water vapor over Turkey using GLONASS and GPS

Abstract

The modernized GLONASS (GLObal NAvigation Satellite System) provides new opportunities for estimating ZWD (zenith wet delay) and PWV (precipitable water vapor) for meteorology and climate related studies. In this study, ZWD/PWV retrieval from GLONASS and GPS (Global Positioning System) observations are assessed by comparing the results with radiosonde observations from nearly co-located GNSS (Global Navigation Satellite Systems) stations. The current consistency between GPS and GLONASS data for ZWD/PWV retrieving is investigated for the first time in the region after the access mode change of the GLONASS. The GPS and GLONASS observations for one month of each season for 8 regionally distributed stations from the CORS-TR (Continuously Operating Reference Stations - Turkey) network are processed. The results show that the GPS ZWD agrees well with the GLONASS ZWD, the RMS (root mean square) of ZWD differences is about 4.1–11.84 mm that is about 0.6–1.78 mm in PWV. ZWD differences are ranged from −20 mm to 20 mm on average for all stations. Correlation coefficients of ZWD differences for GNSS stations exceeds 84%, which means that the results obtained from GLONASS consistent with GPS. Also, PWV estimated from GLONASS observations have almost same RMS values at inland stations, while the combined solution having smallest for most of the stations.