{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,8]],"date-time":"2026-03-08T23:18:30Z","timestamp":1773011910999,"version":"3.50.1"},"reference-count":61,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2023,10,21]],"date-time":"2023-10-21T00:00:00Z","timestamp":1697846400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006190","name":"Gda\u0144sk University of Technology","doi-asserted-by":"publisher","award":["DEC-31\/2021\/IDUB\/I.3.3"],"award-info":[{"award-number":["DEC-31\/2021\/IDUB\/I.3.3"]}],"id":[{"id":"10.13039\/501100006190","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Existing ionospheric models perform very well in mapping the calm state of the ionosphere. However, the problem is accurately determining the total electron content (TEC) for disturbed days. Knowledge of the exact electron density is essential for single\u2212frequency receivers, which cannot eliminate the ionospheric delay. This study aims to investigate temporal and spatial variability in the distribution of TEC based on differences between maps of individual Ionospheric Associated Analysis Centers (IAACs) of the International GNSS Service (IGS) and aligned altimetry\u2212TEC from 2005\u20132021. Based on the temporal distribution, we have observed a significant effect of solar activity on the mean and standard deviation behavior of the differences between global ionospheric maps (GIMs) and Jason\u2212derived TEC. We determined the biases for the entire calculation period, through which it can be concluded that the upcg-Jason and igsg-Jason differences have the lowest standard deviation (\u00b11.81 TECU). In addition, the temporal analysis made it possible to detect annual, semi\u2212annual, and 117-day oscillations occurring in the Jason\u2212TEC data, as well as 121-day oscillations in the GIMs. It also allowed us to analyze the potential sources of these cyclicities, solar and geomagnetic activity, in the case of the annual and semi\u2212annual periodicities. When considering spatial variations, we have observed that the most significant average differences are in the intertropical areas. In contrast, the smallest differences were recorded in the southern hemisphere, below the Tropic of Capricorn (23.5\u00b0S). However, the slightest variations were noted for the northern hemisphere above the Tropic of Cancer (23.5\u00b0N). Our research presented in this paper allows a better understanding of how different methods of GNSS TEC approximation affect the model\u2019s accuracy.<\/jats:p>","DOI":"10.3390\/rs15205053","type":"journal-article","created":{"date-parts":[[2023,10,21]],"date-time":"2023-10-21T12:59:48Z","timestamp":1697893188000},"page":"5053","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Spatio-Temporal Validation of GNSS-Derived Global Ionosphere Maps Using 16 Years of Jason Satellites Observations"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3964-3340","authenticated-orcid":false,"given":"Mateusz","family":"Poniatowski","sequence":"first","affiliation":[{"name":"Faculty of Applied Physics and Mathematics, Gda\u0144sk University of Technology, 80-233 Gda\u0144sk, Poland"},{"name":"Digital Technologies Center, Gda\u0144sk University of Technology, 80-233 Gda\u0144sk, Poland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6827-0205","authenticated-orcid":false,"given":"Grzegorz","family":"Nykiel","sequence":"additional","affiliation":[{"name":"Digital Technologies Center, Gda\u0144sk University of Technology, 80-233 Gda\u0144sk, Poland"},{"name":"Faculty of Civil and Environmental Engineering, Gda\u0144sk University of Technology, 80-233 Gda\u0144sk, Poland"}]},{"given":"Claudia","family":"Borries","sequence":"additional","affiliation":[{"name":"German Aerospace Center, DLR, Institute for Solar-Terrestrial Physics, 17235 Neustrelitz, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6494-1307","authenticated-orcid":false,"given":"J\u0119drzej","family":"Szmytkowski","sequence":"additional","affiliation":[{"name":"Faculty of Applied Physics and Mathematics, Gda\u0144sk University of Technology, 80-233 Gda\u0144sk, Poland"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,21]]},"reference":[{"key":"ref_1","unstructured":"Goodman, J.M. 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