Fig. 1
From: Assessing the quality of ionospheric models through GNSS positioning error: methodology and results
Location of the 34 permanent receivers (triangles) from the MGEX network used to assess GIMs in Orús (2017) and in the present study. The dashed circles enclose the projection area at a 268 km altitude, i.e., the height of the Fast-PPP first layer, and elevation angles higher than 7°. Each point represents the RMS error of the VTEC at one IGP of the IGSG (top left), UQRG (top right) and original Fast-PPP model (bottom left) and recomputed Fast-PPP model (bottom right) at 12 h UT of DOY 079 in 2014. The gray shadow indicates longitudes outside ± 130°