A 2-LAYER MODEL OF THE IONOSPHERE USING GLOBAL POSITIONING SYSTEM DATA

We present a new approach to model the Ionosphere based on GPS data. P revious authors have used models with an unique shell. In this case we have included a second shell to account for the distribution of the e lectrons in the outer part of the Ionosphere. We have analyzed the ion ospheric electron content of a region above 30 degrees in declination in different conditions of ionospheric activity using the Kalman filte r. The data used has been obtained from the International GPS Service fop Geodynamics (IGS) network. Simultaneously we have studied the rece iver and transmitter differential biases showing the effects of neglec ting the outer part of the Ionosphere in the model. It appears a syste matic variations for the receivers-depending on its latitude-not for t he satellites.