Journal of Geodesy

, Volume 85, Issue 12, pp 975–987 | Cite as

Global Ionosphere Maps of VTEC from GNSS, satellite altimetry, and formosat-3/COSMIC data

  • M. M. Alizadeh
  • H. Schuh
  • S. Todorova
  • M. Schmidt
Original Article

Abstract

For space geodetic techniques, operating in microwave band, ionosphere is a dispersive medium; thus signals traveling through this medium are in the first approximation affected proportional to inverse of the square of their frequencies. This effect allows gaining information about the parameters of the ionosphere in terms of Total Electron Content (TEC) or the electron density (Ne). TEC or electron density can then be expressed by means of spherical harmonic base functions to provide a Global Ionosphere Map (GIM). The classical input data for development of GIMs are obtained from dual-frequency observations carried out at Global Navigation Satellite Systems (GNSS) stations. However, GNSS stations are in-homogeneously distributed around the world, with large gaps particularly over the oceans; this fact reduces the precision of the GIM over these areas. On the other hand, dual-frequency satellite altimetry missions such as Jason-1 provide information about the ionosphere precisely above the oceans; and furthermore Low Earth Orbiting (LEO) satellites, such as Formosat-3/COSMIC (F/C) provide well-distributed information of ionosphere globally. This study investigates on global modeling of TEC through combining GNSS and satellite altimetry data with global TEC data derived from the occultation measurements of the F/C mission. The combined GIMs of vertical TEC (VTEC) show a maximum difference of 1.3–1.7 TEC units (TECU) with respect to the GNSS-only GIMs in the whole day. The root mean square error (RMS) maps of combined solution show a reduction of about 0.1 TECU in the whole day. This decrease of RMS can reach up to 0.5 TECU in areas where no or few GNSS observations are available, but high number of F/C measurement is carried out. This proves that the combined GIMs provide a more homogeneous global coverage and higher reliability than results of each single method. All comparisons and validations made within this study provide vital information regarding combination and integration of various observation techniques in the Global Geodetic Observing System of the International Association of Geodesy.

Keywords

Global Ionosphere Maps Total Electron Content Global Navigation Satellite System Satellite altimetry Formosat-3/COSMIC 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. ADSCentral (2007) Altimeter Database System Central, Version 4.00. http://adsc.gfz-potsdam.de/ads/adsCentral_index.html
  2. Bilitza D (1990) International Reference Ionosphere 1990, NSSDC 90-22. Greenbelt, MarylandGoogle Scholar
  3. Bilitza D, Reinisch BW (2008) International Reference Ionosphere 2007: improvements and new parameters. J Adv Space Res 42(#4): 599–609. doi:10.1016/j.asr.2007.07.048 CrossRefGoogle Scholar
  4. Brunini C, Meza A, Bosch W (2005) Temporal and spatial variability of the bias between TOPEX- and GPS-derived total electron content. J Geod 79(4–5): 175–188CrossRefGoogle Scholar
  5. Brunner FK, Gu M (1991) An improved model for the dual frequency ionospheric correction of GPS observations. Manuscr Geod 16: 205–214Google Scholar
  6. Feltens J (2003) The International GPS Service (IGS) Ionosphere Working Group. Adv Space Res 31(3): 635–644CrossRefGoogle Scholar
  7. Feltens J, Angling M, Jakowski N, Mayer C, Hoque M, Hernández-Pajares M, García-Rigo A, Orús-Perez R and Aragón-Angel A (2009) Analysis of the state of the art ionosphere modelling and observation techniques. ESA/ESOC Technical Note OPS-SYS-TN-0017-OPS-GN, Iss. 1/0, 26/06/2009Google Scholar
  8. Feltens J, Angling M, Jackson-Booth N, Jakowski N, Hoque M, Mayer C, Hernández-Pajares M, García-Rigo A, Orús-Perez R, Aragón-Angel A and Zornoza MJ (2010) GNSS contribution to next generation global ionospheric monitoring. ESA/ESOC Final Report DOPS-SYS-RP-5001-OPS-GN, Iss. 1/0, 20/01/2010Google Scholar
  9. Fu LL, Cazenave A (2001) Satellite altimetry and earth sciences. A handbook of techniques and application.. San Diego Academic Press, 463Google Scholar
  10. Hargreaves JK (1995) The solar-terrestrial environment—an introduction to geospace—the science of the terrestrial upper atmosphere, ionosphere, and magnetosphere. Cambridge University Press, LondonGoogle Scholar
  11. Hernandez-Pajares M, Juan JM, Sanz J (1999) New approaches in global ionospheric determination using ground GPS data. J Atmos Sol Terr Phys 61: 1237–1247CrossRefGoogle Scholar
  12. Hernández-Pajares M, Juan JM, Sanz J, Orús-Perez R, García-Rigo A, Feltens J, Komjathy A, Schaer SC and Krankowski A (2009) The IGS VTEC maps: a reliable source of ionospheric information since 1998. J Geod. DOI:10.1007/s00190-008-0266-1
  13. Hochegger G, Nava B, Radicella SM, Leitinger R (2000) A family of ionospheric models for different uses. Phys Chem Earth Part C Sol Terr Planet Sci 25(4): 307–310CrossRefGoogle Scholar
  14. Hofman-Wellenhof, Lichtenegger H, Collins J (1993) GPS theory and practice, 2nd edn. Springer, New YorkGoogle Scholar
  15. Hunsucker RD, Hargreaves JK (2002) The high-latitude ionosphere and its effects on radio propagation. Cambridge University Press, London Cambridge Books Online. (http://dx.doi.org/10.1017/CBO9780511535758.003) Accessed 28 November 2010
  16. Imel DA (1994) Evaluation of the TOPEX/POSEIDON dual-frequency ionosphere correction. J Geophys Res 99(C12): 24895–24906CrossRefGoogle Scholar
  17. Mannucci AJ, Wilson B, Yuan D, Linqwister U, Runge T (1998) A global mapping technique for GPS-derived ionospheric total electron content measurements. Radio Sci 33: 565–582CrossRefGoogle Scholar
  18. Radicella SM, Leitinger R (2001) The evolution of the DGR approach to model electron density profiles. Adv Space Res 27(1): 35–40CrossRefGoogle Scholar
  19. Rawer K, Bilitza D, Ramakrishnan S (1978) Goals and status of the International Reference Ionosphere. Rev Geophys 16: 177–181CrossRefGoogle Scholar
  20. Rishbeth H, Garriott OK (1969) Introduction to ionospheric physics. Academic Press, New YorkGoogle Scholar
  21. Rocken C, Kuo YH, Schreiner W, Hunt D, Sokolovskiy S (2000) COSMIC system description. J Terr Atmos Ocean Sci TAO 11(1): 21–52Google Scholar
  22. Rummel R, Rothacher M, Beutler G (2005) Integrated global geodetic observing system (IGGOS), Science rationale. J Geodyn 40(4–5): 357–362CrossRefGoogle Scholar
  23. Schaer S, Gurtner W, Feltens J (1998) IONEX: The ionosphere map exchange format version 1. In: Proceedings of the IGS Analysis Center Workshop, Darmstadt, pp: 233–247, 9–11 February 1998Google Scholar
  24. Schaer S (1999) Mapping and predicting the Earth’s ionosphere using the Global Positioning System. PhD thesis, Bern University, SwitzerlandGoogle Scholar
  25. Scherliess L, Schunk RW, Sojka JJ, Thompson D (2004) Development of a physics-based reduced state kalman filter for the ionosphere. Radio Sci 39: RS1S04CrossRefGoogle Scholar
  26. Schmidt M, Karslioglu MO, Zeilhofer C (2008) Regional multidimensional modeling of the ionosphere from satellite data. In: Proceedings of the TUJK Annual Scientific Meeting, Ankara, pp: 88–92Google Scholar
  27. Schunk RW, Scherliess L, Sojka JJ, Thompson D (2004) Global assimilation of ionospheric measurements (GAIM). Radio Sci 39: RS1S02. doi:10.1029/2002RS002794 CrossRefGoogle Scholar
  28. Seeber G (1993) Satellite geodesy, foundations, methods and application. Walter de Gruyter, BerlinGoogle Scholar
  29. Todorova S, Schuh H, Hobiger T (2007) Using the Global Navigation Satellite Systems and satellite altimetry for combined Global Ionosphere Maps. Adv Space Res 42: 727–736CrossRefGoogle Scholar
  30. Todorova S (2008) Combination of space geodetic techniques for global mapping of the ionosphere. PhD thesis, Vienna University of Technology, AustriaGoogle Scholar
  31. Tsai LC, Tsai WH (2004) Improvement of GPS/MET ionospheric profiling and validation using the Chung-Li ionosonde measurements and the IRI model. J Terr Atmos Ocean Sci TAO 15(4): 589–607Google Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • M. M. Alizadeh
    • 1
  • H. Schuh
    • 1
  • S. Todorova
    • 2
  • M. Schmidt
    • 3
  1. 1.Institute of Geodesy and GeophysicsVienna University of TechnologyViennaAustria
  2. 2.University of Architecture, Civil Engineering and GeodesySofiaBulgaria
  3. 3.Deutsches Geodätisches Forschungsinstitut (DGFI)MunichGermany

Personalised recommendations