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Development of a regional tropospheric delay model for GPS‐based navigation with emphasis to the Indian Region
Author(s) -
Parameswaran K.,
Saha Korak,
Suresh Raju C.
Publication year - 2008
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2007rs003782
Subject(s) - zenith , global positioning system , gnss applications , troposphere , context (archaeology) , environmental science , meteorology , remote sensing , geodesy , satellite , residual , elevation (ballistics) , computer science , geography , telecommunications , mathematics , algorithm , physics , archaeology , astronomy , geometry
The accuracy of Global Navigation Satellite System (GNSS), aimed to support precise positioning for aircraft navigation globally by coordinating different regional augmentation systems, is limited by the extent to which the atmospheric propagation delay of microwave signals can be modeled. An algorithm is developed for modeling the tropospheric delay based on mean meteorological parameters. A Region‐specific Tropospheric Delay (RTD) model is developed exclusively for the Indian region using meteorological data from the Indian subcontinent, as a part of GPS Aided Geo Augmented Navigation (GAGAN) program. The applicability of this model is examined in the context of the global model used in Wide Area Augmentation System (WAAS), developed employing meteorological data mostly from North American continent, by comparing the estimated zenith tropospheric delay (ZTD) with those obtained from regional models employing measured atmospheric parameters at the surface. The rms deviation of ZTD estimated using RTD model from that of the surface model is found to be ∼5 cm. A further validation by comparing with GPS measurements from two IGS stations at Bangalore and Hyderabad showed that predictions made using the RTD model are within an rms deviation of ±5 cm while those using WAAS model is ±7 cm. Maximum value of the residual error for RTD model is ∼15 cm, which corresponds to a ∼0.5 m error in the vertical coordinates for the lowest satellite elevation angles usually encountered.