Comparison between IRI and GPS-IGS derived electron content during 1991-97

The existence of a permanent network of GPS ground receivers, the Internati onal GPS Service (IGS), with available data since 1991, allows to perform a n exhaustive comparison of the global electron content derived from these d ata using tomographic models with the International Reference Ionosphere (I RI) predictions. This work will allow the IRI upgrading for the electron co ntent forecast, using this data set at global scale and along more than hal f solar cycle. In this contribution we present a comparison involving more than 1300 stations times day worldwide distributed between 1991 (similar or equal to 10 stations) and 1997 (similar or equal to 200 stations). (C) 199 9 Elsevier Science Ltd. All rights reserved.