Abstract:
Water vapor is a dynamic component of the atmosphere that significantly influences atmospheric stabilization mechanisms. However, measuring and modeling water vapor using traditional meteorological systems or models is challenging. The tropical atmosphere, containing the largest amount of water vapor, exhibits high climate uncertainty. To address this, geodesists have developed methods to estimate atmospheric water vapor-induced signal delays in Global Navigation Satellite System (GNSS) data.
In this study, we assess the integrated water vapor (IWV) over NIGNET CORS using GPS data. The main objectives of the study were achieved in three phases. Firstly, the Zenith Path Delay (ZPD) was assessed, and it was found that station ULAG had the highest ZPD estimate of 2731.104mm, while station CGGT had the lowest estimate of 2129.924mm. The ZPD estimates showed good correlation (R2 = 70%) with International GNSS Service (IGS) estimations.
Secondly, the IWV was estimated using surface temperature and pressure data. Since the NIGNET CORS surface data were unavailable, the GPT2w_1 model was used to generate the required data. The IWV was computed by combining the ZWD with the weighted mean temperature derived from the surface temperature and pressure. Spatial and seasonal variations of IWV over the NIGNET CORS were analyzed, revealing higher IWV values over southern stations and during the rainy season. The estimated IWV was validated with data from ECMWF ERA-5 interim, showing a considerable correlation of 0.6 with the NIGNET IWV.
The results indicate that GPS-based IWV effectively captures the IWV trend over Nigeria. It is recommended to extend the assessment of IWV over all NIGNET CORS stations for longer periods to facilitate better spatial and temporal analysis
Exploring GNSS-Based Integrated Water Vapor Assessment via Nigeria CORS Network. GET MORE, ACTUARIAL SCIENCE PROJECT TOPICS AND MATERIALS
