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GPS Coordinate Estimates by “a priori” Tropospheric Delays from NWP using Ultra-Rapid Orbits
Language
English
Status
Unpublished
JCR Journal
JCR Journal
Peer review journal
Yes
Volume or Series
4-5/49(2006)
Issued date
November 28, 2006
Abstract
Comparisons of high accuracy GPS positioning estimates using scientific GPS software through three different processing strategies have been done. The two Italian baselines in a time period of 5 months during 2004 made a calculus data set.
For high accuracy GPS differential positioning the employ of global tropospheric delay models can be replaced by the implementation of other techniques. The GPS coordinate repeatability when the tropospheric delay is calculated in near-real time (NRT) from a Numerical Weather Prediction (NWP) model, is experienced. For the NRT approach IGS Ultra-Rapid orbits instead of Precise orbits were used.
Concerning coordinate repeatability, the NWP-based strategy with tropospheric error adjustment appeared as the more accurate (at the submillimetric level) with respect to a standard GPS strategy. Furthermore, several hundreds km long baselines demonstrated the standard deviation at the level of millimeters (from 4.2 to 7.6 mm). Practically, the NWP-based strategy offers the advantage of tropospheric delay estimations closer to realistic meteorological values.
The application of a more accurate meteorology leads to the satisfactory coordinate estimations, and vice versa the well-defined GPS estimations of coordinates may serve as the additional meteorological parameters source.
For high accuracy GPS differential positioning the employ of global tropospheric delay models can be replaced by the implementation of other techniques. The GPS coordinate repeatability when the tropospheric delay is calculated in near-real time (NRT) from a Numerical Weather Prediction (NWP) model, is experienced. For the NRT approach IGS Ultra-Rapid orbits instead of Precise orbits were used.
Concerning coordinate repeatability, the NWP-based strategy with tropospheric error adjustment appeared as the more accurate (at the submillimetric level) with respect to a standard GPS strategy. Furthermore, several hundreds km long baselines demonstrated the standard deviation at the level of millimeters (from 4.2 to 7.6 mm). Practically, the NWP-based strategy offers the advantage of tropospheric delay estimations closer to realistic meteorological values.
The application of a more accurate meteorology leads to the satisfactory coordinate estimations, and vice versa the well-defined GPS estimations of coordinates may serve as the additional meteorological parameters source.
References
1. Beutler G., I. Bauersima, W. Gurtner, M. Rothacher, T. Schildknecht and A. Geiger (1988): Atmospheric refraction and other important biases in GPS carrier phase observations, in Atmospheric Effects on Geodetic Space Measurements, Monograph 12, pp. 15-43, School of Surveying, University of New south Wales, Kensington, Australia.
2. Bevis M., S. Businger, S. Chriswell, T.A. Herring, C. Rocken and R.H. Ware (1994): GPS Meteorology: Mapping Zenith wet Delays onto Precipitable Water, J. Appl. Meteorol., 33, 379-386.
3. Cucurull L., P. Sedo, D. Behrend, E. Cardellach and A. Rius (2002): Integrating NWP products into the analysis of GPS observables, Phys. Chem. Earth (A), 27, 377-383.
4. Davis J.L., T.A. Herring, I.I. Shapiro, A.E.E. Rogers and G. Elgered (1985): Geodesy by radio interferometry: effects of atmospheric modeling errors on estimates of baseline length, Radio Sci., 20, 1593-1607.
5. DWD (2003): DWD Quarterly Report of the German NWP-System, Deutscher Wetterdienst, no. 3.
6. Fazlagic S, (2003): A Large Fluctuation of Relative Positions of GPS Receivers as a Possible Indicator of a Too Poor Meteorological Knowledge Given by NWP Models, Ph. D. Thesis, University of Genoa.
7. Hugentobler U., S. Schaer and P. Fridez (eds) (2001): Bernese GPS Software Version 4.2, Documentation of the Bernese GPS Software Version 4.2, Astronomical Institute University of Berne, Switzerland.
8. Jensen A.. B. O., C. C. Tscherning and F. Madsen (2002): Integrating Numerical Weather Predictions in GPS Positioning, Proc. of ENC GNSS-2002, Copenhagen, May, 2002.
9. Kleijer F. (2004): Troposphere modeling and filtering from precise GPS leveling, Publications on Geodesy, no. 56, Netherland Geodetic Commission, Delft.
10. Saastamoinen J., (1972): Atmospherics Correction for the Troposphere and Stratosphere in Radio Ranging of Satellite, in The Use of Artificial Satellites for Geodesy, Geophys. Monogr. Ser., AGU, Washington D.C., 15, 247 – 251.
11. Solheim F.S., J. Vivekanandan, R.H. Ware, and C. Rocken (1999): Propagation delays induced in GPS signals by dry air, water vapor, hydrometeors, and other particulates, J. Geoph. Res., 104 (D8), 9663- 9670.
12. Springer T. A. and U. Hugentobler (2001): IGS Ultra Rapid Products for (Near-) Real-Time Applications, Phys. Chem. Earth (A), 26, No. 6-8, 623-628.
13. Thayer G.(1974): An improved equation for the radio refractive index of air, Radio Sci., 9, 803-807.
14. Vedel H., K.S. Mogensen and Y. Huang (2001): Calculation of zenith delays from meteorological data comparison of NWP model, radiosonde and GPS delays, Phys. Chem. Earth (A), 26, No. 6-8, 497-582.
2. Bevis M., S. Businger, S. Chriswell, T.A. Herring, C. Rocken and R.H. Ware (1994): GPS Meteorology: Mapping Zenith wet Delays onto Precipitable Water, J. Appl. Meteorol., 33, 379-386.
3. Cucurull L., P. Sedo, D. Behrend, E. Cardellach and A. Rius (2002): Integrating NWP products into the analysis of GPS observables, Phys. Chem. Earth (A), 27, 377-383.
4. Davis J.L., T.A. Herring, I.I. Shapiro, A.E.E. Rogers and G. Elgered (1985): Geodesy by radio interferometry: effects of atmospheric modeling errors on estimates of baseline length, Radio Sci., 20, 1593-1607.
5. DWD (2003): DWD Quarterly Report of the German NWP-System, Deutscher Wetterdienst, no. 3.
6. Fazlagic S, (2003): A Large Fluctuation of Relative Positions of GPS Receivers as a Possible Indicator of a Too Poor Meteorological Knowledge Given by NWP Models, Ph. D. Thesis, University of Genoa.
7. Hugentobler U., S. Schaer and P. Fridez (eds) (2001): Bernese GPS Software Version 4.2, Documentation of the Bernese GPS Software Version 4.2, Astronomical Institute University of Berne, Switzerland.
8. Jensen A.. B. O., C. C. Tscherning and F. Madsen (2002): Integrating Numerical Weather Predictions in GPS Positioning, Proc. of ENC GNSS-2002, Copenhagen, May, 2002.
9. Kleijer F. (2004): Troposphere modeling and filtering from precise GPS leveling, Publications on Geodesy, no. 56, Netherland Geodetic Commission, Delft.
10. Saastamoinen J., (1972): Atmospherics Correction for the Troposphere and Stratosphere in Radio Ranging of Satellite, in The Use of Artificial Satellites for Geodesy, Geophys. Monogr. Ser., AGU, Washington D.C., 15, 247 – 251.
11. Solheim F.S., J. Vivekanandan, R.H. Ware, and C. Rocken (1999): Propagation delays induced in GPS signals by dry air, water vapor, hydrometeors, and other particulates, J. Geoph. Res., 104 (D8), 9663- 9670.
12. Springer T. A. and U. Hugentobler (2001): IGS Ultra Rapid Products for (Near-) Real-Time Applications, Phys. Chem. Earth (A), 26, No. 6-8, 623-628.
13. Thayer G.(1974): An improved equation for the radio refractive index of air, Radio Sci., 9, 803-807.
14. Vedel H., K.S. Mogensen and Y. Huang (2001): Calculation of zenith delays from meteorological data comparison of NWP model, radiosonde and GPS delays, Phys. Chem. Earth (A), 26, No. 6-8, 497-582.
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This paper has been accepted to be published on Annals of Geophysics
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