Ionospheric indices GIX and SIDX and related perturbation scales

Abstract

Ionospheric perturbations can seriously affect accuracy, continuity, availability, and integrity of space-based radio systems such as Global Navigation Satellite Systems (GNSS) and remote sensing radars. To mitigate ionospheric impact on trans-ionospheric radio signals or at least to improve the performance of operating radio systems, a reliable knowledge of the type, intensity and dynamic of ionospheric perturbations in space and time is required in near real time. The talk will describe the methodological background of the ionospheric indices Gradient Ionosphere indeX (GIX) and the Sudden Ionosphere Disturbance indeX (SIDX) to characterize spatial and temporal variations of the ionospheric plasma. The spatial scale focuses on the km range from a few km to about 1000 km, whereas the temporal scale focuses on a few seconds to about 1 hour. Capabilities, strengths and limitations of these ionospheric indices will be reviewed considering sample studies under various geophysical conditions. GIX and SIDX provide a complementary information on the instantaneous perturbation degree of the ionosphere in space and time and are therefore well suited to serve operational applications. We will present index and application related perturbation scales to support the practical use of indices in operational radio systems