Abstract
Satellite navigation systems face different types of errors that affect the positioning accuracy. The tropospheric delay considers one of the major sources of error for the transmitted signal that could face a tropospheric delay of over 2 m at zenith and 20 m at lower satellite elevation angles. A positioning error of 10 m could result from inaccurate mitigation of the tropospheric delay. Two types of models are available; surface meteorological models and global empirical models. Surface meteorological models use surface meteorological data to give accurate mitigation while the global empirical models use global standard atmospheres. Global empirical models are favorable for satellite based augmentation systems such as EGNOS model for the EGNOS augmentation system. Several hybrid neutral atmosphere delay models have been developed (UNB1 through UNB4). The IGGtrop model is initially developed to provide tropospheric delay corrections for the users of Chinese BeiDou Navigation Satellite System (BDS) and its augmentation system. This paper presents an assessment study for the behaviour of IGGtrop model comparing with (EGNOS, UNB3M) models. The behavior of the three models is compared with IGS-tropospheric estimations for two different-latitude IGS stations; ( bhr1 and eil1) in the northern hemisphere. This study recommends using IGGtrop model for estimating the zenith tropospheric delay correction for low-latitude regions in northern hemisphere for all seasons with an average zenith tropospheric difference of 0.75 cm. IGGtrop model is also recommended to be used for estimating the zenith tropospheric delay correction for high-latitude geographic regions in northern hemisphere during autumn and spring seasons with an average zenith tropospheric difference of 0.75 cm. While UNB3M model is the best choice for tropospheric delay correction for high-latitude geographic regions in northern hemisphere during winter and summer seasons with an average zenith tropospheric difference of 1.1 cm.