4-D Modeling of Water Vapour using a Regional GPS Network

S. Skone, S.M. Shrestha

Abstract:	Global Positioning System (GPS) signals experience range delays dependent on several physical parameters in the neutral atmosphere. Such delays are generally classified as wet delay, which is a function of water vapour pressure and temperature, and dry delay, which is a function of air pressure and temperature. By using differential GPS techniques, and a precise hydrostatic model, it is possible to recover estimates of the zenith wet overlying a given GPS reference station. In recent years, novel techniques have been developed to derive slant wet delay estimates for all satellites in view at a given station. Observations of the slant wet delay may be derived at a number of regional network sites, and used to model both the vertical and horizontal structure of water vapour in a 4-D tomographic modeling approach. Such techniques allow improved resolution of wet refractivity profiles for precise positioning applications and assimilation into numerical weather predictions (NWP). The University of Calgary is currently developing a regional network with sixteen dual-frequency GPS reference stations in Southern Alberta. Network observations will be streamed in real-time to a centralized processing facility at University of Calgary. In this paper, we present strategies for 4-D real-time modeling of refractivity profiles and water vapour within the regional network.
Published in:	Proceedings of the 2003 National Technical Meeting of The Institute of Navigation January 22 - 24, 2003 Disneyland Paradise Pier Hotel Anaheim, CA
Pages:	809 - 816
Cite this article:	Skone, S., Shrestha, S.M., "4-D Modeling of Water Vapour using a Regional GPS Network," Proceedings of the 2003 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2003, pp. 809-816.
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