EGNOS test bed ionospheric corrections under the October and November 2003 storms

Two severe geomagnetic storms were experienced on October 29-31 and November 20, 2003, degrading significantly the European Geostationary Navigation Overlay Service (EGNOS) Test Bed (ESTB) performance in Europe. Such storms reached extreme values of Kp=9 during the most severe periods. The analysis of the ESTB ionospheric corrections and their effect on the ESTB integrity and accuracy is presented in this work. The ESTB performance during those storms was monitored from a network of global positioning system (GPS) receivers widely distributed over Europe, including the ESTB reference stations, and the geographical degradation of the accuracy is analyzed in this paper. The correlation between the Kp index and the misleading information (MI) events is also shown. During the most severe stormy periods, the errors in the ESTB ionospheric corrections and its integrity bounds are analyzed to explain the peaks in the navigation system error, which produces MIs. This analysis has been carried out by comparing with direct dual-frequency GPS measurements and global ionospheric maps.