Near Real Time Gps-Based Ionospheric Models : Application to Belgium

A good knowledge in near real-time of the state of the ionosphere, in terms of spatial and temporal variation of electron content, is now necessary for many scientific applications. Indeed, most of the applications using radio waves (e.g. communications, navigations systems and radio-sciences) are biased by the ionosphere. They consequently need information on the ionospheric electron content over a specific area at a given time e.g. to derive delay corrections. In this study, we present a method developed at the Royal Observatory of Belgium in order to produce each 15 minutes GPS-based ionospheric total electron content models over Europe on a 0.5°/0.5° grid for any user located in Belgium. The foreseen product will be available in near real-time and therefore the 120 stations of the EUREF Permanent Network providing near real-time GPS data are used. In a first step, the method is described (input data, parameter estimations) and the data cleaning and the spatial interpolation approaches are presented. In a second step, the results of the selected spline interpolation method are shown and the resulting models are compared to Global Ionospheric Maps produced by the CODE (Center for Orbit Determination in Europe) IGS analysis center. The quality of the product is evaluated during different periods: (1) active ionospheric state (October Geomagnetic Storm, 2003); (2) normal ionospheric state (close to the Solar Minimum in 2008); (3) and a recent period in 2010.