Systematic behavior of semiempirical global ionospheric models in quiet geomagnetic conditions

Semiempirical ionospheric models are widely used in many applications. In this work we analyze the global representation of the vertical total electron content (VTEC) derived from the La Plata single‐layer GPS ionospheric model (LPIM), the international reference ionosphere (IRI) model, and the Bent model. To perform this analysis, we compare the output from these models with VTEC determinations from the TOPEX/Poseidon (T/P) satellite. The analysis of the differences is performed over a large number of selected quiet geomagnetic days during the year 1997. From these comparisons we can conclude that LPIM gives the best global VTEC representation, even without modeling the ionospheric equatorial anomaly. The mean global difference between the VTEC determined by T/P and computed by LPIM is in the range of 2 and 3 TECU (1 TECU = 1016 el/m2). IRI and Bent models tend to show larger discrepancies with T/P during the summer solstices in both Northern and Southern Hemispheres.