Abstract:

Troposphere anomaly must be monitored to ensure navigation accuracy and integrity when the Ground-Based Augmentation System （GBAS） provides services for safety-critical applications. The maximum tolerable troposphere delay in measurement domain and the troposphere anomaly probability are the critical parameters for GBAS troposphere anomaly integrity monitors. In this paper， the required navigation performance in the position domain is translated into the required integrity monitoring performance in the measurement domain from an airworthiness perspective. The maximum tolerable troposphere delay in the measurement domain is quantified based on the worst protection principle. The probabilities of troposphere duct anomaly and non-nominal troposphere delay are evaluated using the meteorological data from European Center for Medium-range Weather Forecasts （ECMWF） during 2010-2019. Real BDS data and meteorological data are used to carry out simulation. The experimental results show that to ensure the integrity and availability of precise approach and landing services supported by GBAS， the maximum tolerable troposphere delay in the measurement domain ranges from 0.57 to 0.92 m （corresponding glide angle \theta=2.5°- 3.5°）. The prior probability of troposphere duct anomaly is between 10% - 50% in most coastal areas， but its impact on the integrity of GBAS is negligible. The prior probability of non-nominal troposphere delay can be conservatively set as 5.3×10 ^-3 to improve the integrity of GBAS. The results can provide an important reference for the design of troposphere anomaly integrity monitor and the improvement of GBAS integrity monitoring system.

Key words: troposphere duct anomaly, non-nominal troposphere delay, integrity, ground-based augmentation system (GBAS), global navigation satellite system (GNSS)