Performance Evaluation of Blind Tropospheric Delay correction Models over Africa
Tropospheric delay is a major error source in positioning by Global Navigation Satellite Systems (GNSS). Many techniques are available for tropospheric delay mitigation consisting of surface meteorological models and global empirical models. Surface meteorological models need surface meteorological data to give high accuracy mitigation while the global empirical models need not. However, most GNSS stations in the African region are not equipped with a meteorological sensor for the collection of surface meteorological data during the measurement. Zenith Tropospheric Delay (ZTD) is often calculated by the various high precision GNSS software packages by utilising standard atmosphere values. Lately, researchers in the University of New Brunswick and Vienna University of Technology have both developed global models (University of New Brunswick (UNB3M) and Global Pressure and Temperature 2 wet (GPT2w) models) for tropospheric delay correction, respectively. This report represents an appraisal of the performance of the GPT2w and UNB3M models with accurate International GNSS Service (IGS)- tropospheric estimations for fifteen IGS stations over a period of 1 year on the Africa continent. Both models perform significantly better at low latitudes than higher latitudes. There was better agreement between the GPT2w model and the IGS estimate than the UNB3m at all stations. Thus, the GPT2w model is recommended as a correction model of the tropospheric error for the GNSS positioning and navigation on the African Continent.
Keywords: Global Navigation Satellite Systems (GNSS), Zenith Tropospheric Delay (ZTD), Zenith Wet Delay (ZWD), Zenith Hydrostatic Delay (ZHD), International GNSS Service (IGS), Blind Tropospheric models