Mitigation of ionospheric effects on GNSS positioning over Antarctica: a case study during low solar activity

Abstract

The aim of this study is to investigate the performance of a method based on improving the stochastic model to mitigate ionospheric scintillation effects on GNSS positioning by processing experimental data from GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers, which are capable of computing amplitude and phase scintillation parameters from GPS signals. We applied the approach to mitigate ionospheric scintillation effects on GNSS positioning, in conjunction with the estimation of an ionospheric parameter, considered as a stochastic process. This approach produced, in a single epoch point positioning solution, an improvement on height and 3D accuracy of the order of 31% and of 45%, respectively, when applied in a northern high latitude GISTM network under a moderate scintillation scenario. In this project we investigated the case study of 21 November 2009 using data from GISTM stations located in Antarctica and applying the same scintillation mitigation approach to a Precise Point Positioning (PPP) solution. We used an in-house software under development at Unesp. Despite the solar activity being very low, observations from ACE indicated the influence of a recurrent coronal hole high speed stream. Solar wind speed ranged from 430 to 575 km/s, with Bz fluctuations from -8 to +9 nT, generally leading to the formation of ionospheric irregularities responsible of scintillation effects on GNSS signals. Preliminary results from this case study in the PPP mode are encouraging, showing improvements of the order of 26% in 3D accuracy when applying the proposed scintillation stochastic modeling.