Ionosphere modelling for Galileo single frequency users: illustration of the combination of the NeQuick model and GNSS data ingestion

Abstract The ionospheric effect remains one of the main factors limiting the accuracy of Global Navigation Satellite Systems (GNSS) including Galileo. For single frequency users, this contribution to the error budget will be mitigated by an algorithm based on the NeQuick global ionospheric model. This quick-run empirical model provides flexible solutions for combining ionospheric information obtained from various sources, from GNSS to ionosondes and topside sounders. Hence it constitutes an interesting simulation tool not only serving Galileo needs for mitigation of the ionospheric effect but also widening the use of new data. In this study, we perform slant TEC data ingestion – the optimisation procedure underlying the Galileo single frequency ionospheric correction algorithm – into NeQuick for a dozen locations around the world where both an ionosonde and a GPS receiver are installed. These co-located instruments allow us to compare measured and modelled vertical TEC showing for example global statistics or dependence towards latitude. We analyse measurements for the year 2002 (high solar activity level) giving an insight into the situation we could observe when Galileo reaches its Full Operation Capability, during the next solar maximum. At last we compare Galileo and GPS ionospheric corrections. For Galileo, we end up with an underestimation of 11% and 4% depending on the version of NeQuick embedded in the algorithm, as well as a 22% standard deviation. This means respectively twice, five and 1.5 times better than GPS.

[1]  A. Garcia-Rigo,et al.  The IGS VTEC maps: a reliable source of ionospheric information since 1998 , 2009 .

[2]  Ioannis A. Daglis,et al.  Space Weather: Physics and Effects , 2007 .

[3]  Iwona Stanislawska,et al.  Near Earth space plasma monitoring under COST 296 , 2009 .

[4]  R. Warnant,et al.  The increase of the ionospheric activity as measured by GPS , 2000 .

[5]  Ljiljana R. Cander,et al.  Testing regional vertical total electron content maps over Europe during the 17–21 January 2005 sudden space weather event , 2007 .

[6]  E. V. Appleton,et al.  Book reviewMeteorological and astronomical influences on radio wave propagation: Edited by B. Landmark, Pergamon Press, Oxford, 1963. 318 pp., 100s , 1963 .

[7]  Sandro M. Radicella,et al.  A new version of the NeQuick ionosphere electron density model , 2008 .

[8]  Bodo W. Reinisch,et al.  Ionosonde networking, databasing, and Web serving , 2006 .

[9]  Justine Spits,et al.  Mitigation of ionospheric effects on GNSS , 2009 .

[10]  Chris Rizos,et al.  The International GNSS Service in a changing landscape of Global Navigation Satellite Systems , 2009 .

[11]  René Warnant,et al.  Assessment of the NeQuick model at mid-latitudes using GNSS TEC and ionosonde data , 2010 .

[12]  Reinhart Leitinger,et al.  Topside electron density in IRI and NeQuick: Features and limitations , 2006 .

[13]  Sandro M. Radicella,et al.  The evolution of the DGR approach to model electron density profiles , 2001 .

[14]  J. Klobuchar.  Ionospheric Time-Delay Algorithm for Single-Frequency GPS Users , 1987, IEEE Transactions on Aerospace and Electronic Systems.

[15]  René Warnant,et al.  Measuring total electron content with GNSS: Investigation of two different techniques , 2009 .

[16]  Sandro M. Radicella,et al.  A near‐real‐time model‐assisted ionosphere electron density retrieval method , 2006 .

[17]  R. Brent.  Table errata: Algorithms for minimization without derivatives (Prentice-Hall, Englewood Cliffs, N. J., 1973) , 1975 .

[18]  Sandro M. Radicella,et al.  Calibration errors on experimental slant total electron content (TEC) determined with GPS , 2007 .

[19]  Richard A. Snay,et al.  Continuously Operating Reference Station (CORS): History, Applications, and Future Enhancements , 2008 .

[20]  René Warnant,et al.  Towards an Improved Single - Frequency Ionospheric Correction: Focus on Mid - Latitudes , 2008 .

[21]  Ivan A. Galkin,et al.  Data ingestion and assimilation in ionospheric models , 2009 .

[22]  B. Arbesser-Rastburg,et al.  Effects on satellite navigation , 2007 .