ABSTRACT
Water vapour is a very dynamic component of the atmosphere. It greatly influences the atmospheric stabilization mechanism. Hence, it is very difficult to measure or model using classical meteorological systems or models. Tropical atmosphere holds the largest amount of water vapour, thus its characteristics of high climate uncertainty. Interestingly, geodesists have devised methods for estimating the extent to which signals propagated from GNSS satellites to ground‐based GNSS receivers are delayed by atmospheric water vapor. This delay is parameterized in terms of a time‐varying zenith wet delay (ZWD) which is retrieved by stochastic filtering of the GNSS data. Given surface temperature and pressure readings at the GNSS receiver, the retrieved ZWD can be transformed with very little additional uncertainty into an estimate of the integrated water vapor (IWV) overlying that receiver. Therefore, this study is to assess the integrated water vapor over NIGNET CORS using GPS data. Three specific objectives were set for the study which was conducted in three phases. The first objective assessed the Zenith Path Delay (ZPD). The highest and the lowest ZPD estimates are respectively 2731.104mm at station ULAG and 2129.924mm at station CGGT and the analysis showed good correlation with the IGS (ZPD). The average correlation (R2 ) of 70% was obtained showing a very strong agreement with IGS estimation. The second objective was the estimation of IWV. Surface temperature and pressure data were utilized to obtain the integrated water vapor (IWV). The surface temperature and pressure data of the NIGNET CORS were not readily available, therefore the GPT2w_1 model was used to generate the surface temperature and pressure. The surface temperature and pressure were then used to compute the weighted mean temperature which was combined with the ZWD to obtain IWV. Spatial and seasonal variation of IWV value over the NIGNET CORS was performed and it was found that the highest IWV values were obtained over the southern stations just as the rainy season presents the period of high IWV values over all stations. The estimated IWV was validated with IWV generated from ECMWF ERA-5 interim data and it shows a considerable correlation with the estimated NIGNET IWV, the average correlation of 0.6 was obtained. It was deduced from the study that GPS-based IWV properly captured the IWV trend over Nigeria. It is strongly recommended that assessment of IWV over all the NIGNET CORS should be extended for longer years for better spatial and temporal analysis.
ABSTRACT
According to Locke, knowledge is restricted to ideas, not platonic ideas or forms, but ideas t...
Abstract
The study examined the impact of domestic debt on economic development of Nigeria with a view...
ABSTRACT
This study was carried out to examine hooliganism/gangsterism and students’ academi...
BACKGROUND INFORMATION
Planning is one of the most important aspects in the management o a firm. It inv...
ABSTRACT
The study was carried out on housing conditions and occupancy ratio in Okpoko urban and regional planning. The...
ABSTRACT
The purpose of this research work is to investigate the effect of class size in effective teaching and lear...
Abstract
The study examined the Effect of Graphics on the Print Media using Osun Defender newspaper as a case study. How...
ABSTRACT
Radiation exposure during diagnostic X-ray examinations has been widely reported as one of the sources of cancer induction. Info...
Abstract
The study examined the relevance of Business Education program to economic development of Nigeria. The study fo...
ABSTRACT
This study examined the profitability of layers production in Esan North East and Ovia North East L.G.A’s...