Performance of global and regional ionospheric maps over a low latitude region

Abstract

Vertical total electron content (VTEC) values are commonly distributed in regular grids by means of the so-called global ionospheric maps (GIMs). Besides the global products, several analysis centers also compute regional ionospheric maps (RIMs) which often incorporate a larger number of GNSS stations, i.e. a denser network, allowing the description of finer structures of the ionosphere. The different global and regional ionospheric products can also present some differences, for instance related to spatial and temporal resolutions. In this work we present a comparison of the performance of seven ionospheric maps: four global, two regional and one hybrid product, which combines regional and global data. The assessment/validation is performed based in ionosonde data and global navigation satellite systems (GNSS) positioning. Data from ionosondes and GNSS stations over the Brazilian region is used during a week with active geomagnetic storm. In general, the performance of RIM products leads to better results considering the ionosonde data approach. The assessment with GNSS positioning leads to larger errors close to the equatorial anomaly; the best performance is obtained with the proposed hybrid product.