GNSS-CORS as water vapor sensors for local atmospheric monitoring: Comparing high-end geodetic-grade and low-cost stations in S Spain

In order to study a possible densification of the regional GNSS network in S Spain, a local cost-effective GNSS network has been installed in the province of Jaén: JAENet. This network is the first one installed in Spain to analyze the GNSS-derived Precipitable Water Vapor (GNSS-PWV) and its time variations. JAE1 is the first low-cost GNSS Continuously Operating Reference Station (GNSS-CORS) setup. It is strategically located very close to UJAE, a high-end geodetic-grade GNSS-CORS, in order to investigate the GNSS-PWV at the same geographic location and under the same environmental and atmospheric conditions. This study aims to evaluate the performance of low-cost GNSS devices for atmospheric water vapor monitoring through an experimental design and the first comparison of data coming from low-cost and high-precision devices over a period of more than one year. Eighteen months divided into six seasonal periods is considered. The common GNSS data period for both GNSS-CORS has been processed using the Precise Point Positioning (PPP) method to estimate their coordinates and evaluate the Zenith Tropospheric Delay (ZTD) using open-source GNSS software. The results show a good agreement between JAE1 and UJAE ZTD time series, with differences ranging from −11.59 mm to 10.12 mm, a mean difference value at the 2-mm level and a remarkably high correlation equal to 0.99. The difference between the mean of GNSS-PWV at GNSS-CORS throughout the six periods analyzed is always under the 1-mm level. The results show that low-cost GNSS-CORS are promising as water vapor sensors for local atmospheric monitoring.