The Use of NWP Products in Near Real-Time GPS Data Processing

D. Behrend, L. Cucurull, E. Cardellach, A. Rius, M.J. Sedo and A. Nothnagel

Abstract:	We investigate the eect of the choice of \a priori" information for the troposphere in the evaluation of Global Positioning System (GPS) data, since the commonly used standard atmosphere values may dier considerably from the actual atmospheric conditions. A means to obtain more realistic initial values may be the use of numerical weather prediction (NWP) models. Thus, the impact of the ingestion of zenith hydrostatic (ZHD) and zenith wet delay (ZWD) values derived from a operational NWP model into the GPS data processing is analysed. As meteorological information we use 1 hour time series of ZHD and ZWD that have been forecasted by the NWP model HIRLAM. The investigation is done for the three International GPS Service for Geodynamics (IGS) stations Villafranca, Wettzell, and Zimmerwald. In the case of not estimating the troposphere, 1-h solutions furnish signicantly better results when using the HIRLAM derived tropospheric information. The repeatabilities of the vertical coordinate component drop from 0:1 : : : 0:2 m with standard a-prioris to 0:02 : : : 0:05 m in the HIRLAM case. In case the tropospheric parameters are being estimated as well, the results from hourly batches become unclear. While two stations have smaller repeatabilities with the standard a-priories, one station shows the opposite behaviour. Thus, for small estimation intervals (1 hour and less) the choice of initial values for the troposphere may have a signicant eect on the estimation results.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	2499 - 2506
Cite this article:	Behrend, D., Cucurull, L., Cardellach, E., Rius, A., Sedo, M.J., Nothnagel, A., "The Use of NWP Products in Near Real-Time GPS Data Processing," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 2499-2506.
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