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Abstract
GNSS Positioning - Some Recent Developments and Trends
Dr. Ahmed El-Rabbany
Professor
Department of Civil Engineering
Ryerson University
Canada
Tropospheric delay is one of the dominant Global Positioning System (GPS) errors that degrades the positioning accuracy. Recent developments in tropospheric modelling rely on implementation of more accurate Numerical Weather Prediction (NWP) models. In North America, one of the NWP-based tropospheric correction models is the NOAA model, which has been developed by the US National Oceanic and Atmospheric Administration (NOAA). Because of its potential to improve the GPS positioning accuracy, the NOAA tropospheric correction model became a focus of many researchers.In this research, we examined the performance of the NOAA model and studied its effect on the GPS positioning accuracy. We generated a three-year-long tropospheric zenith total delay (ZTD) data series for the NOAA, Hopfield, and the IGS final tropospheric correction product, respectively. These three sets of data series were generated at ten IGS reference stations spanning North America. We analysed the NOAA ZTD data series and compared it with those of the Hopfield model. The IGS final tropospheric product was used as a reference. The analysis showed that the NOAA model is largely season dependent and its performance was superior to the Hopfield model. We further investigated the effect of implementing the NOAA model on the positioning accuracy, which again behaved better than the Hopfield model.
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