Novel ionospheric activity indicator specifically tailored for GNSS users

Abstract

This work introduces a novel ionospheric activity indicator useful for identifying disturbed periods affecting performance for GNSS users, at regional level. This indicator is based in the “Along Arc TEC Rate (AATR) and can be easily computed from GNSS data. The AATR indicator has been assessed over more than one Solar Cycle (2002-2013) involving 140 receivers distributed world-wide. Results show that it is well correlated with the ionospheric activity and, unlike other global indicators linked to the geomagnetic activity (i.e. DST, Ap), it is sensitive to regional behaviour the ionosphere and identifies specific effects on GNSS users. Moreover from a devoted analysis of EGNOS performances in different ionospheric conditions, it follows that the AATR indicator is able to predict SBAS user availability anomalies linked to the ionosphere. The AATR indicator has been chosen as the metric to characterise the ionosphere operational conditions in the frame of EGNOS activities. This indicator has been also proposed for joint analysis in the International SBAS-Ionosphere Working Group.