Assessment of global ionospheric maps over continental areas using precise point positioning technique

In this study, an approach based on precise point positioning (PPP) is proposed for the assessment of global ionospheric maps (GIMs). This assessment is performed by comparing GIMs with vertical total electron content (VTEC) values retrieved using the PPP technique. The results indicate that the CODG, ESAG, WHUG, and CASG ionospheric products underestimate the VTEC values. There is a high level of consistency between all GIMs and PPP-VTEC values during periods of low solar activity. In addition, almost all GIMs exhibit significant discrepancies with PPP-VTEC values over the equatorial ionisation anomaly (EIA) region during periods of high solar activity.