Two-way assessment ionospheric maps performance over the Brazilian region: Global versus regional products

Vertical total electron content (VTEC) has great importance in describing the ionosphere. VTEC values are commonly distributed in regular grids by means of so-called global ionospheric maps (GIMs) and regional ionospheric maps (RIMs). Although considerable research has been conducted to develop regional and global models, there is no clear understanding of the benefits of using RIMs over GIMs. Aiming to contribute to this discussion, our investigation presents a comparison between seven global and regional ionospheric maps considering two approaches: (a) ionosonde data-based assessment and (b) global navigation satellite systems (GNSS) positioning assessment. A challenging low latitude ionosphere scenario, the Brazilian region, was selected during a week with an active geomagnetic storm. The assessment results with ionosonde data have shown better performance of the RIM products named OTHR and OTRG. Among the global products, CODG and UQRG have shown the best performances. The worst results were obtained with the RIM named Instituto Nacional de Pesquisas Espaciais. The assessment with GNSS positioning led to larger and noisier errors close to the equatorial anomaly. Two of the analyzed RIMs presented expected large errors in stations at the edges of the coverage area. To overcome this issue, a hybrid product was proposed to extend the RIM covered region. The proposed hybrid product (OTRG) presented the best results in the GNSS positioning domain.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001 and Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP: 2021/05285-0). UPC-IonSAT also thanks the partial support of the PITHIA NRF EU project (Grant 101007599). We acknowledge the IGS IAACs, in particular CODE, for providing the ionospheric data, INPE for providing the ionospheric regional maps and the ionosonde data, IBGE for providing the GNSS data, and the National Institute of Science and Technology for GNSS in Support of Air Navigation (INCT GNSS-NavAer), funded by CNPq (465648/2014-2), FAPESP (2017/50115-0), and CAPES (88887.137186/2017-00). We are also greatful to the Bundeswehr GeoInformation Centre (BGIC) and the German Space Situation Awareness Centre (GSSAC) for funding the “Operational tool for ionosphere mapping and prediction” (OPTIMAP) project.Peer reviewe