European Navigation Conference 2005-Munich Assessment of EGNOS performance in worst ionosphere conditions (October and November 2003 storm)

Cristoforo Montefusco, Javier Ventura-Traveset, B Arbesser-Rastburg, Franck Froment, Didier Flament, Eduardo Tapias, S Radicella, R Leitinger
1. Abstract This paper presents the results of an assessment on EGNOS performance during a severe solar storm occurred at the end of October 2003 and affecting the propagation of radio waves through the ionosphere. The relevance of this assessment is that this storm is one of the largest occurred during the last solar cycle, and one of the worst ionospheric storms ever recorded. This paper will show that EGNOS is able to provide a reliable service over the whole service region with reasonable
more » ... n with reasonable degradations, as well as vertical guidance capability (APV) over most of Europe during this abnormal ionosphere conditions. These are extremely encouraging result that reinforces the confidence on the EGNOS safety design and algorithmic conception 2. Introduction One of the system requirements of the EGNOS system is to provide the users with frequent and reliable data to correct the pseudo-range measurements affected by the delay introduced in the propagation of radio waves through the ionized layers of the atmosphere. This function is accomplished by the EGNOS central processing facility through the use of a model of the ionosphere behaviour dynamically driven by real time measurements carried out in the EGNOS reference stations (RIMS-Ranging and Integrity Monitoring Station.) In some circumstances, sudden variations in the solar activity may lead the ionosphere to behave in a way far different from the nominal behaviour. This happens during severe ionosphere storms. In these cases, it is essential for a safety system like EGNOS, to confirm that the integrity of the computed corrections and the continuity of service are still maintained. Qualification of EGNOS performance (both at