Characterization of the ionospheric scintillation impacts as measured by the Rate of TEC index (ROTI)

Pierre Cilliers - South African National Space Agency; Tshimangadzo Matamba - South African National Space Agency, South Africa

Session: Thermosphere-Ionosphere Interactions and Effects

Abstract

This paper presents an attempt to characterize the impacts of ionospheric scintillation as measured by means of the Rate of Change of TEC Index (ROTI) on navigation accuracy. Ionospheric scintillation indices are required products for the Aviation navigation support services by ICAO. These include the amplitude (S₄) and phase scintillation (σ_φ) indices as well as the ROTI which is a proxy for the conventional scintillation indices.  The ROTI product is derived from RINEX data logged by standard dual frequency receivers of the Global Navigation Satellite System (GNSS) of which there are many more than there are L-band scintillation monitors. The ROTI product is a potentially useful proxy for the S₄ product over regions where there is a scarcity of dedicated high sampling rate ionospheric scintillation receivers especially over the equator. ICAO does not currently provide any specification of thresholds for alerts based on the ROTI product. The navigation errors are quantified in terms of kinematic position errors, cycle slips, loss-of-lock, carrier-to-noise-density ratio, and number of visible satellites and correlated with estimations of the ROTI index as derived from both 1-s and 30-s RINEX data. These results may be useful for the establishment of thresholds for alerts on the ROTI product.