When compared to the wide range of atmospheric sensing techniques, global navigation satellite system (GNSS) offers the advantage of operating under all weather conditions, is continuous, with high temporal and spatial resolution and high accuracy, and has long-term stability. The utilisation of GNSS ground networks of continuous stations for operational weather and climate services is already in place in many nations in Europe, Asia, and America under different initiatives and organisations. In Africa, the situation appears to be different. The focus of this paper is to assess the conditions of the existing and anticipated GNSS reference network in the African region for meteorological applications. The technical issues related to the implementation of near-real-time (NRT) GNSS meteorology are also discussed, including the data and network requirements for meteorological and climate applications. We conclude from this study that the African GNSS network is sparse in the north and central regions of the continent, with a dense network in the south and fairly dense network in the west and east regions of the continent. Most stations lack collocated meteorological sensors and other geodetic observing systems as called for by the GCOS Reference Upper Air Network (GRUAN) GNSS Precipitable Water Task Team and the World Meteorological Organization (WMO). Preliminary results of calculated zenith tropospheric delay (ZTD) from the African GNSS indicate spatial variability and diurnal dependence of ZTD. To improve the density and geometry of the existing network, countries are urged to contribute more stations to the African Geodetic Reference Frame (AFREF) program and a collaborative scheme between different organisations maintaining different GNSS stations on the continent is recommended. The benefit of using spaced based GNSS radio occultation (RO) data for atmospheric sounding is highlighted and filling of geographical gaps from the station-based observation network with GNSS RO is also proposed.

Weighted mean temperature (Tm) is a critical parameter in the estimation of precipitable water vapour from ground‐based Global Navigation Satellite System (GNSS) receivers. In the present study, three models of Tm are developed for GNSS meteorological applications in the West African region in general and Nigeria in particular. The first is a least squares linear regression model based on National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis II data for Nigeria from 2010 to 2012. A regression of 37 330 data pairs of surface temperature and Tm calculated from the vertical profiles of temperature above each grid node of the reanalysis model was used to produce the Nigerian Weighted Mean Temperature Equation‐I (NWMTE‐I) model after outlier data were removed. By using the same approach, NWMTE‐II was obtained from 11 433 radiosonde profiles from 24 sounding stations in the West African region for the period 2009–2013. NWMTE‐III was produced from a combination of the data used to build NWMTE‐I and NWMTE‐II. To evaluate the accuracy of these three models, they were compared with four global models based on Tm obtained by using the integral method, which was the reference model for this study. The normalized mean absolute error, root‐mean‐square error, model efficiency, reliability index and correlation co‐efficient were used as performance indicators. The performances of the developed models were promising compared with the global models, justifying the importance of using measured meteorological parameters when estimating Tm and fine tuning Tm to specific areas or regions. Finally, NWMTE‐III is recommended for Nigerian users and NWMTE‐II for users in the West African region.

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