Abstract
This paper presents a technique for ingesting ground- and space-based dual-frequency GPS observations into a semi-empirical global electron density model. The NeQuick-2 model is used as the basis for describing the global electron density distribution. This model is mainly driven by the F2 ionosphere layer parameters (i.e. the electron density, N m F2, and the height, h m F2 of the F2 peak), which, in the absence of directly measured values, are computed from the ITU-R database (ITU-R 1997). This database was established using observations collected from 1954 to 1958 by a network of around 150 ionospheric sounders with uneven global coverage. It allows computing monthly median values of N m F2 and h m F2 (intra-month variations are averaged), for low and high solar activity. For intermediate solar activity a linear interpolation must be performed. Ground-based GNSS observations from a global network of ~350 receivers are pre-processed in order to retrieve slant total electron content (sTEC) information, and space-based GPS observations (radio occultation data from the FORMOSAT-3/COSMIC constellation) are pre-processed to retrieve electron density (ED) information. Both, sTEC and ED are ingested into the NeQuick-2 model in order to adapt N m F2 and h m F2, and reduce simultaneously both, the observed minus computed sTEC and ED differences. The first experimental results presented in this paper suggest that the data ingestion technique is self consistent and able to reduce the observed minus computed sTEC and ED differences to ~25–30% of the values computed from the ITU-R database. Although sTEC and ED are both derived from GPS observations, independent algorithm and models are used to compute their values from ground-based GPS observations and space-based FORMOSAT-3/COSMIC radio occultations. This fact encourages us to pursue this research with the aim to improve the results presented here and assess their accuracy in a reliable way.
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References
Aragón-Ángel A, Hernández-Pajares M, Juan JM, Sanz J (2009) Improving the Abel transform inversion using bending angles from FORMOSAT-3/COSMIC, GPS Solut, doi:10.1007/s10291-009-0147-y
Azpilicueta F, Brunini C, Radicella SM (2005) Global ionospheric maps from GPS observations using modip latitude. JASR, Elsevier, Amsterdam (36):552–561
Bailey GJ, Balan N, Su YZ (1997) The Sheffield University plasmasphere ionosphere model: a review. J Atmos Sol Terr Phys 59: 1541–1552
Bilitza D (2001) International Reference Ionosphere 2000. Radio Sci 36(2): 261–275
Dudeney JR (1974) A Simple Empirical Method for Estimating the Height of the F2-Layer at the Argentine Islands Graham Land, Science Report No 88, British Antarctic Survey, London, UK
Feess WA, Stephens SG (1987) Evaluation of GPS ionospheric time delay model. IEEE Trans Aerosp Electron Syst 23(3): 332–338
Feltens J (1998) Chapman profile approach for 3-D global TEC representation. In: Dow JM, Kouba J, Springer T (eds) Proceedings of the IGS Analysis Center Workshop, Darmstadt pp 285-297
Feltens J, Schaer S (1998) IGS products for the ionosphere. In: Dow JM, Kouba J, Springer T (eds) Proceedings of the IGS Analysis Center Workshop, 225-232, Darmstadt, 1998
Hajj GA, Ibanez-Meier R, Kursinski ER, Romans LJ (1994) Imaging the ionosphere with global positioning system. Int J Imaging System Technology 5: 174–184
Hernández-Pajares M, Juan JM, Sanz J (1999) New approaches in global ionospheric determination using ground GPS data. J Atmos Sol Terr Phys 61: 1237–1247
Hernández-Pajares M, Juan JM, Sanz J (2000) Improving the Abel inversion by adding ground GPS data to LEO radio occultations in ionospheric sounding. Geop Res Lett 27(16): 2473–2476
Hernández-Pajarez M, Juan JM, Sanz J, Orus R, Garcia-Rigo A, Feltens J, Komjathy A, Schaer SC, Krankowski A (2009) The IGS VTEC map: a reliable source of ionospheric information since 1998. J Geod 83: 263–275
Huba JD, Joyce G, Fedder JA (2000) Sami2 is another model of the ionosphere (SAMI2): a new low-latitude ionosphere model. J Geophys Res 105(A10), 23, 035-23,054
ITU-R (1997) Recommendation ITU-R P.1239, ITU-R reference ionospheric characteristics, International Telecommunications Union, Radio - Communication Sector, Geneva
Jakowski N, Leitinger R, Angling M (2004) Radio occultation techniques for probing the ionosphere. Ann Geophys, Suppl. 47(2/3): 1049–1066
Jodogne JC, Nebdi H, Warnant R (2004) GPS TEC and ITEC from digisonde data compared with NEQUICK model. Adv Sapce Res 2: 269–273
Jones WB, Gallet RM (1965) The representation of diurnal and geographical of ionospheric delay by numerical methods. Telecomm J 32: 18
Kleusberg A (1986) Ionospheric propagation effects in geodetic relative GPS positioning. Manuscripta Geodaetica 11: 256–261
Lanyi GE, Roth T (1988) A comparison of mapped and measured total ionospheric electron content using Global Positioning System and beacon satellite observations. Radio Sci 23(4): 483–492
Leitinger R, Ladreiter HP, Kirchengast G (1997) Ionosphere tomography with data from satellite reception of GNSS signals and ground reception of NNSS signals. Radio Sci 32(4): 1657–1669
Manucci AJ, Iijima BA, Lindqwister UJ, Pi X, Sparks L, Wilson BD (1999) GPS and ionosphere, revised submission to URSI reviews of Radio Sci, Jet Propulsion Laboratory, Pasadena, California
Manucci AJ, Wilson BD, Yuan DN, Ho CM, Lindqwister UJ, Runge TF (1998) A global mapping technique for GPS-derived ionospheric total electron-content measurements. Radio Sci 33(3): 565–582
Nava B, Coïsson P, Radicella SM (2008) A New version of the NeQuick ionosphere electron density model. J Atmos Sol Terr Phys, pp. 1856–1862 doi:10.1016/j.jastp.2008.01.015
Orús R, Hernández-Pajares M, Juan JM, Sanz J (2005) Improvement of global ionospheric VTEC maps by using kriging interpolation technique. J Atmos Sol Terr Phys 67(16): 1598–1609
Radicella SM, Leitinger R (2001) The evolution of the DGR approach to model electron density profiles. Adv Space Res 27(1):35–40
Sardon E, Rius A, Zarraoa N (1994) Estimation of the transmitter and receiver differential biases and the ionospheric total electron content from Global Positioning System observations. Radio Sci 29: 577–586
Schaer S, Beutler G, Rothacher M, Soringer T (1996) Daily global ionosphere maps based on GPS carrier phase data routinely produced by the CODE Analysis Center. In: Proceedings of the IGS Analysis Center Workshop, Silver Spring
Schmidt M, Bilitza D, Shum CK, Zeilhofer C (2008) Regional 4-D modeling of the ionospheric electron density. Adv Space Res 42: 782–790
Schreiner WS, Sokolovskiy SV, Rocken C, Hunt DC (1999) Analysis and validation of GPSMET radio occultation data in the ionosphere. Radio Sci 34: 949–966
Schunk RW (2002) Global Assimilation of Ionospheric Measurements (GAIM), paper presented at Ionospheric Effects Symposium, Office of Naval Research, Alexandria, VA
Wang C, Hajj G, Pi X, Rosen IG, Wilson B (2004) Development of the global assimilative ionospheric model, Radio Sci, 39, doi:10.1029/2002RS002854
Wild U, Beutler G, Gurtner W, Rothacher M (1989) Estimating the ionosphere using one or more dual frequency GPS receivers. In: Proceedings of the Fifth International Geodetic Symposium on Satellite Positioning, Las Cruces, pp 724-736
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Brunini, C., Azpilicueta, F., Gende, M. et al. Ground- and space-based GPS data ingestion into the NeQuick model. J Geod 85, 931–939 (2011). https://doi.org/10.1007/s00190-011-0452-4
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DOI: https://doi.org/10.1007/s00190-011-0452-4