Journal of Geodesy

, 79:613 | Cite as

Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign

  • K. Snajdrova
  • J. Boehm
  • P. Willis
  • R. Haas
  • H. Schuh
Original Article


In October 2002, 15 continuous days of Very Long Baseline Interferometry (VLBI) data were observed in the Continuous VLBI 2002 (CONT02) campaign. All eight radio telescopes involved in CONT02 were co-located with at least one other space-geodetic technique, and three of them also with a Water Vapor Radiometer (WVR). The goal of this paper is to compare the tropospheric zenith delays observed during CONT02 by VLBI, Global Positioning System (GPS), Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) and WVR and to compare them also with operational pressure level data from the European Centre for Medium-Range Weather Forecasts (ECMWF). We show that the tropospheric zenith delays from VLBI and GPS are in good agreement at the 3–7 mm level. However, while only small biases can be found for most of the stations, at Kokee Park (Hawaii, USA) and Westford (Massachusetts, USA) the zenith delays derived by GPS are larger by more than 5 mm than those from VLBI. At three of the four DORIS stations, there is also a fairly good agreement with GPS and VLBI (about 10 mm), but at Kokee Park the agreement is only at about 30 mm standard deviation, probably due to the much older installation and type of DORIS equipment. This comparison also allows testing of different DORIS analysis strategies with respect to their real impact on the precision of the derived tropospheric parameters. Ground truth information about the zenith delays can also be obtained from the ECMWF numerical weather model and at three sites using WVR measurements, allowing for comparisons with results from the space-geodetic techniques. While there is a good agreement (with some problems mentioned above about DORIS) among the space-geodetic techniques, the comparison with WVR and ECMWF is at a lower accuracy level. The complete CONT02 data set is sufficient to derive a good estimate of the actual precision and accuracy of each geodetic technique for applications in meteorology.


Troposphere Zenith delay GPS VLBI DORIS Water Vapor Radiometer 


  1. Altamimi Z, Sillard P, Boucher C (2002) A new release of the international terrestrial reference frame for Earth science applications. J Geophys Res Solid Earth 107(B10):2214CrossRefGoogle Scholar
  2. Bar-Sever YE, Kroger PM, Borjesson JA (1998) Estimating horizontal gradients of tropospheric path delay with a single GPS receiver. J Geophys Res Solid Earth 103(B3):5019–5035CrossRefGoogle Scholar
  3. Behrend D, Cucurull L, Vilà J, Haas R (2000) An inter-comparison study to estimate zenith wet delays using VLBI, GPS, and NWP models. Earth Planets Space 52:691–694Google Scholar
  4. Behrend D, Haas R, Pino D, Gradinarsky LP, Keihm SJ, Schwarz W, Cucurull L, Rius A (2002) MM5 derived ZWDs compared to observational results from VLBI, GPS and WVR. Phys Chem Earth 27:3301–308Google Scholar
  5. Beutler G, Rothacher M, Schaer S, Springer TA, Kouba J, Neilan RE (1999) The International GPS Service (IGS), an interdisciplinary service in support of Earth Sciences. Adv Space Res 23(4):631–653CrossRefGoogle Scholar
  6. Bevis M, Businger S, Chiswell S, Herring TA, Anthes RA, Rocken C, Ware RH (1994) GPS meteorology: mapping zenith Wet delays onto precipitable water. J Appl Meteorol 33(3):379–386CrossRefGoogle Scholar
  7. Boehm J (2004) Troposphärische Laufzeitverzögerungen in der VLBI, Geowissenschaftliche Mitteilungen, Heft Nr. 68, ISSN 1811–8380Google Scholar
  8. Boehm J, Schuh H (2004) Vienna mapping functions in VLBI analyses. Geophys Res Lett 31(1):L01603, DOI:10.1029/2003GL018984CrossRefGoogle Scholar
  9. Chao BF, Ray RD, Gibson JM, Egbert GD, Ma C (1996) Diurnal/semidiurnal polar motion excited by oceanic tidal angular momentum. J Geophys Res Solid Earth 101(B9):20151–20163CrossRefGoogle Scholar
  10. Cucurull L, Vandenberghe F (1999) Comparison of PW estimates from MM5 and GPS data. In: Proceedings of MM5 Workshop’99, Boulder, ColoradoGoogle Scholar
  11. Cucurull L, Navascues B, Ruffini G, Elósegui P, Rius A, Vilà J (2000) The use of GPS to validate NWP systems: the HIRLAM model. J Atmos Oceanic Technol 17:773–787CrossRefGoogle Scholar
  12. Davis JL, Herring TA, Shapiro II., Rogers AEE, Elgered G (1985) Geodesy by radio interferometry: effects of atmospheric modeling errors on estimates of baseline length. Radio Sci 20(6):1593–1607CrossRefGoogle Scholar
  13. Davis JL, Elgered G, Niell AE, Kuehn CE (1993) Ground-based measurements of gradients in the “wet” radio refractivity of air. Radio Sci 28(6):1003–1018CrossRefGoogle Scholar
  14. Dudhia J, Gill D, Guo YR, Manning K, Wang W (2001) PSU/NCAR mesoscale modeling system tutorial class notes and user’s guide (MM5 modelling system version 3). In: Mesoscale and Microscale Meteorology Division, National Center for Atmospheric Research, p. 300, Boulder, ColoradoGoogle Scholar
  15. Elgered G (1993) Tropospheric radio path delay from ground-based microwave radiometry. In: Janssen M (eds). Atmospheric remote sensing by microwave radiometry. Wiley, New York, pp 215–258Google Scholar
  16. Elgered G, Jarlemark POJ (1998) Ground-based microwave radiometry and long-term observations of atmospheric water vapor. Radio Sci 33(3):707–717CrossRefGoogle Scholar
  17. Fagard H (2002) Station renovation at Kauai (Hawaii, USA), DORISMail#0208, December 10, 2002,–12/msg00001.htmlGoogle Scholar
  18. Gendt G (2004) Report of the Tropospheric Working Group for 2002. In: Gowey K, Neilan R, Moore A (eds). 2001–2002 Technical Report IGS Central Bureau. Jet Propulsion Laboratory, PasadenaGoogle Scholar
  19. Gipson JM (1996) Very long baseline interferometry determination of neglected tidal terms in high-frequency Earth orientation variation. J Geophys Res Solid Earth 101(B12):28051–28064CrossRefGoogle Scholar
  20. Gradinarsky LP, Haas R, Elgered G, Johansson JM (2000) Wet path delay and delay gradients inferred from microwave radiometer, GPS and VLBI observations. Earth Planets Space 52(10):695–698Google Scholar
  21. Haas R, Gradinarsky LP, Johansson JM, Elgered G (1999) The atmospheric propagation delay: a common error source for collocated space techniques of VLBI and GPS. In: Proceedings of International Workshop “Geod. Meas. Coll. Spac Tech. Earth” (GEMSTONE). Koganei, Tokyo, pp 230–234Google Scholar
  22. Haase JS, Vedel H, Ge M, Calais E (2001) GPS zenith troposphere delay (ZTD) variability in the mediterranean. Phys Chem Earth 26:439–443CrossRefGoogle Scholar
  23. Hajj GA, Ao CO, Iijima BA, Kuang D, Kursinski ER, Mannucci AJ, Meehan TK, Romans LJ, Juarez MD, Yunck TP (2004) CHAMP and SAC-C atmospheric occultation results and intercomparisons. J Geophys Res Atmos 109(D6):D06109CrossRefGoogle Scholar
  24. Hatanaka Y, Sawada M, Horita A, Kusaka M (2001) Calibration of antenna-radome and monument-multipath effect of GEONET, part 1, measurement of phase characteristics. Earth Planets Space 53(1):13–21Google Scholar
  25. Jarlemark POJ (1994) Microwave radiometry for studies of variations in atmospheric water vapor and cloud liquid content. Licentiate thesis, Technical Report 181L, Chalmers University of Technology, Göteborg, SwedenGoogle Scholar
  26. Källén E (1996) HIRLAM documentation manual, system 2.5, Technical Report, SMHI, Norrköping, SwedenGoogle Scholar
  27. Lanyi G (1984) Tropospheric delay effects in radio interferometry. In: The telecommunications and data acquisition progress report, 42–78, 152–159. Jet Propulsion Laboratory, California Institute of Technology, PasadenaGoogle Scholar
  28. Liebe HJ (1992) Atmospheric spectral properties between 10 and 350 GHz: new laboratory measurements and models. In: Westwater ER (ed) Proceedings of the specialist meeting on microwave radiometry and remote sensing applications. Wave Propagation Laboratory, NOAA, Boulder, Colorado, USA, pp 189–196Google Scholar
  29. Mangiarotti S, Cazenave A, Soudarin L, Cretaux JF (2001) Annual vertical crustal motions predicted from surface mass redistribution and observed by space geodesy. J Geophys Res Solid Earth 106(B3):4277–4291CrossRefGoogle Scholar
  30. Morel L, Willis P (2002) Parameter sensitivity of TOPEX orbit and derived mean sea level to DORIS stations coordinates. Adv Space Res 30(2):255–263CrossRefGoogle Scholar
  31. Niell AE (1996) Global mapping functions for the atmosphere delay at radio wavelengths. J Geophys Res 101(B2):3227–3246CrossRefGoogle Scholar
  32. Niell AE, Coster AJ, Solheim FS, Mendes VB, Toor PC, Langley RB, Upham CA (2001) Comparison of measurements of atmospheric wet delay by radiosonde, water vapor radiometer, GPS, and VLBI. J Atmos Oceanic Technol 18:830–850CrossRefGoogle Scholar
  33. Owens JC (1967) Optical refractive index of air: dependence on pressure, temperature and composition. Appl Opt 6(1):51–59CrossRefGoogle Scholar
  34. Rocken C, Sokolovskij S, Johnson JM, Hunt D (2001) Improved mapping of tropospheric delays. J Atmos Oceanic Technol 18(7): 1205–1213CrossRefGoogle Scholar
  35. Saastamoinen J (1973) Contribution to the theory of atmospheric refraction (in three parts). Bullet Géodésique 105–107: 279–298, 383–397, 13–34Google Scholar
  36. Schlueter W, Himwich E, Nothnagel A, Vandenberg NR, Whitney A (2002) IVS and its important role in the maintenance of the global reference systems. Adv Space Res 30(2):145–150CrossRefGoogle Scholar
  37. Schmid R, Rothacher M (2003) Estimation of elevation-dependent Satellite antenna phase center variations of GPS Satellites. J Geod 77(7–8):440–446CrossRefGoogle Scholar
  38. Schuh H, Boehm J (2003) Status Report of the IVS pilot project–tropospheric parameters. In: Vandenberg NR, Baver KD (eds). International VLBI service for geodesy and astrometry 2002 annual report. NASA/TP-2003–211619. Goddard Space Flight Center, MarylandGoogle Scholar
  39. Tapley BD, Bettadpur S, Ries JC, Thompson PF, Watkins MM (2004) GRACE measurements of mass variability in the earth system. Science 305(5683):503–505CrossRefPubMedGoogle Scholar
  40. Tavernier G, Soudarin L, Larson K, Noll C, Ries J, Willis P (2002) Current status of the DORIS pilot experiment and the future International DORIS Service. Adv Space Res 30(2):151–156CrossRefGoogle Scholar
  41. Tavernier G, Granier JP, Jayles C, Sengenes P, Rozo F (2003) Current evolutions of the DORIS system. Adv Space Res 31(8): 1947–1952CrossRefGoogle Scholar
  42. Tavernier G, Fagard H, Feissel-Vernier M, Lemoine F, Noll C, Willis P (2005) The international DORIS service (IDS). Adv Space Res, 36(3):333–341, DOI:10.1016/j.asr.2005.03.102CrossRefGoogle Scholar
  43. Thomas C, MacMillan DS (2003) Core operation center report. In: Vandenberg NR, Baver KD (eds). International VLBI service for geodesy and astrometry 2002 annual report. NASA/TP-2003–211619. Goddard Space Flight Center, Maryland, pp. 1–1Google Scholar
  44. Tomassini M, Gendt G, Dick G, Ramatschi M, Shraff C (2002) Monitoring of integrated water vapour from Ground-based GPS observations and their assimilation in a limited-area NWP model. Phys Chemis Earth 27(4–5):341–346CrossRefGoogle Scholar
  45. Ware R, Exner M, Feng D, Gorbunov M, Hardy K, Herman B, Kuo Y, Meehan T, Melbourne W, Rocken C, Schreiner W, Sokolovski S, Solheim F, Zou X, Anthes R, Businger S, Trenberth K (1996) GPS sounding of the atmosphere from low earth orbit, preliminary results. Bull Amer Meteorolog Soc 77(1):19–40CrossRefGoogle Scholar
  46. Webb FH, Zumberge JF (1995) An introduction to GIPSY/OASIS-II. JPL Publication D-11088, Jet Propulsion Laboratory, PasadenaGoogle Scholar
  47. Willis P, Heflin B (2004) External validation of the GRACE GGM01C gravity field using GPS and DORIS positioning results. Geophys Res Lett 31(13):L13616CrossRefGoogle Scholar
  48. Willis P, Haines B, Berthias JP, Sengenes P, Le Mouel JL (2004) Behavior of the DORIS/Jason oscillator over the South Atlantic Anomaly. CR Geosci 336(9):839–846CrossRefGoogle Scholar
  49. Willis P, Boucher C, Fagard H, Altamimi Z (2005a) Applications géodésiques du système DORIS a l’Institut Géographique National, Geodetic applications of the DORIS system at the French Institut Géographique National. CR Geosci 337(7):653–662, DOI: 10.1016/j.crte.2005.03.002CrossRefGoogle Scholar
  50. Willis P, Bar-Sever Y, Tavernier G (2005b) DORIS as a potential part of a global geodetic observing system. In: Drewes H (ed) Special issue on GGOS. J Geodynamics, 40(4–5):494–501, DOI:10.1016/j.jog.2005.06.011Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • K. Snajdrova
    • 1
    • 2
  • J. Boehm
    • 1
  • P. Willis
    • 3
    • 4
  • R. Haas
    • 5
  • H. Schuh
    • 1
  1. 1.Institute of Geodesy and GeophysicsVienna University of TechnologyViennaAustria
  2. 2.Institute of GeodesyBrno University of TechnologyBrnoCzech Republic
  3. 3.Institut Géographique NationalDirection techniqueSaint-MandeFrance
  4. 4.Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaUSA
  5. 5.Onsala Space Observatory, Department of Radio and Space ScienceChalmers University of Technology92 OnsalaSweden

Personalised recommendations