Ionospheric indices for characterizing ionospheric perturbations and warning users of trans-ionospheric radio systems

Abstract

Severe ionospheric plasma perturbations can seriously affect the accuracy, continuity, availability, and integrity of space-based radio systems such as Global Navigation Satellite Systems (GNSS) and remote sensing radars. Computing well-defined ionospheric indices can help to characterize the type and degree of ionospheric perturbations and to improve our understanding of the underlying physics of these perturbations. Additionally, indices can warn users concerning the ionospheric impact on the performance of radio systems like GNSS. Users are interested in receiving near real-time information about the type, intensity, and dynamics of ionospheric perturbations over time and space. This talk will address these topics based on recent DLR developments on ionospheric indices, such as the Gradient Ionosphere indeX (GIX) and the Sudden Ionosphere Disturbance indeX (SIDX). The capabilities, strengths, and limitations of these indices will be reviewed by considering sample studies under various geophysical conditions. The talk will underline the practical value of continuously monitoring and computing these indices at the national Ionospheric Monitoring and Prediction Center (IMPC) at DLR. This information service predicts the occurrence of severe perturbations and warns customers, particularly those in safety-critical applications such as aviation or automated GNSS positioning and navigation devices. To enable customers to permanently estimate the risk level of violating performance criteria required in the specific radio system they use, we suggest index-based perturbation scales of ionospheric electron density.