Reference : Assessment of the NeQuick Model at Mid-latitudes using GPS TEC and Ionosonde Data
Scientific congresses and symposiums : Paper published in a book
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
Engineering, computing & technology : Electrical & electronics engineering
Assessment of the NeQuick Model at Mid-latitudes using GPS TEC and Ionosonde Data
Bidaine, Benoît mailto [Université de Liège - ULiège / FNRS > Département de Géographie - Departement of Geography > Unité de Géomatique - Geomatics Unit > > >]
Warnant, René mailto [Institut Royal Météorologique - IRM - Royal Meteorological Institute - RMI > > > >]
First Colloquium Scientific and Fundamental Aspects of the Galileo Programme
First Colloquium Scientific and Fundamental Aspects of the Galileo Programme
du 1 octobre 2007 au 4 octobre 2007
Académie de l'Air et de l'Espace - ANAE
Agence Spatiale Européenne - European Space Agency - ESA
[en] ionosphere ; model ; NeQuick ; ionosonde ; mid-latitudes ; Dourbes ; TEC ; mitigation ; positioning ; GNSS ; Galileo ; single frequency
[fr] Géodésie et GNSS
[en] The ionosphere plays a crucial role in Global Navigation Satellite Systems (GNSS) accuracy. In extreme cases, this electrically charged part of the atmosphere can lead to errors in positioning exceeding 100 $m$. At first approximation, ionospheric effects depend mainly on the total content in free electrons of the ionosphere ("total electron content", TEC). The modelling of the latter parameter reveals thus itself critical in particular for single frequency receivers, the most common ones constituting the mass market. In the framework of GALILEO, the NeQuick model has been chosen to this extent and will be integrated into a global algorithm providing the users with daily updated information.

In order to reach the specified correction level, the model itself and its latest evolutions as well as its use for GALILEO are investigated. As a first step in a thorough analysis, we take benefit of ionosonde and GPS TEC data from the Dourbes Geophysical Observatory (Belgium) to study the mid-latitudes. Constraining the model with ionosonde measurements, we first investigate the difference between GPS-derived vertical TEC (vTEC) for Dourbes station and corresponding values from NeQuick for the latest years for solar maximum in 2002 and minimum in 2006. With this approach, we reach residual errors of about 20% RMS for 2002 and 30% for 2006. Through a focusing process, we identify then gradually best and worst months and days for which we observe the evolution between two versions of NeQuick. We highlight among others improvements from the latest modification in the topside formulation which appears clearly in the electron density profiles examined at the end of the assessment.
Researchers ; Professionals

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