GNSS single frequency ionospheric range delay corrections: NeQuick data ingestion technique Original Research Article

A study of the performance of the NeQuick model and the Klobuchar model for GNSS single frequency range delay correction on a global scale was done using data for moderate solar activity. In this study NeQuick was used in the way intended for Galileo. This study is to assess the performance of the two models at each ionospheric geographic region during moderate solar activity as previously published studies were concentrated only on high solar activity. The results obtained showed that NeQuick outperformed Klobuchar for the whole year at the three geographical regions of the ionosphere. In terms of monthly root mean square of mismodeling, NeQuick outperformed Klobuchar by 15 TECU or more at low-latitudes, 5 TEC or more at mid-latitudes, and 1 TECU or more at high-latitudes. Also, a study on how the data ingestion technique already developed for NeQuick could be expanded in order to reduce the deviation of NeQuick TEC prediction from observation for a particular day based on the information from the previous day was done. Instead of obtaining a regularly spaced Az grid from monitoring stations spread across the region of interest, we obtained hourly Az coefficients from hourly Az from designated monitoring stations. The obtained hourly Az coefficients were then used to drive NeQuick for the next day at the test stations. The results obtained, in terms of daily RMS of mismodeling, showed a daily maximum improvement of 26.0% at low-latitudes, 54.9% at mid-latitudes, and 41.3% at high-latitudes.