{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:15:33Z","timestamp":1760148933714,"version":"build-2065373602"},"reference-count":17,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,6,19]],"date-time":"2023-06-19T00:00:00Z","timestamp":1687132800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000780","name":"Radio-Occultation Meteorology Satellite Application Facility (ROM SAF)","doi-asserted-by":"publisher","award":["H2020-INFRAIA-2018-2020 101007599","CEX2020-001058-M-20-","PID2021-126436OB-C22"],"award-info":[{"award-number":["H2020-INFRAIA-2018-2020 101007599","CEX2020-001058-M-20-","PID2021-126436OB-C22"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]},{"name":"EC-funded PITHIA-NRF","award":["H2020-INFRAIA-2018-2020 101007599","CEX2020-001058-M-20-","PID2021-126436OB-C22"],"award-info":[{"award-number":["H2020-INFRAIA-2018-2020 101007599","CEX2020-001058-M-20-","PID2021-126436OB-C22"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>This paper presents a new way of combining Abel inversion and the Chapman model with a linearly increasing scale height to retrieve ionospheric electron density vertical profiles from truncated-sounding radio-occultation data. A linear Vary\u2013Chap model is used to cover the blind region due to data truncation, with parameters estimated by enumeration of the possible values in a grid centered around a set of parameters compatible with ionospheric physics. The resulting electron density is estimated with its corresponding error from the linear least-squares solution presenting the smaller post-fit residual on the input GNSS carrier-phase measurements. The results, tested on a set of representative GNSS RO measurements obtained by COSMIC\/FORMOSAT-3, show that this method can retrieve EDVPs with a predominant absolute and relative error of 1010e\u2212m\u22123 and 5%, respectively, and in less than 10 s per profile, which makes this method suitable for near real-time applications in upcoming missions such as EUMETSAT Polar System-Second Generation.<\/jats:p>","DOI":"10.3390\/rs15123176","type":"journal-article","created":{"date-parts":[[2023,6,19]],"date-time":"2023-06-19T02:29:19Z","timestamp":1687141759000},"page":"3176","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Real-Time Tomographic Inversion of Truncated Ionospheric GNSS Radio Occultations"],"prefix":"10.3390","volume":"15","author":[{"given":"Germ\u00e1n","family":"Olivares-Pulido","sequence":"first","affiliation":[{"name":"UPC-IonSAT, Universitat Polit\u00e8cnica de Catalunya, 08034 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9687-5850","authenticated-orcid":false,"given":"Manuel","family":"Hern\u00e1ndez-Pajares","sequence":"additional","affiliation":[{"name":"UPC-IonSAT, Universitat Polit\u00e8cnica de Catalunya, 08034 Barcelona, Spain"},{"name":"Institut d\u2019Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4907-0494","authenticated-orcid":false,"given":"Enric","family":"Monte-Moreno","sequence":"additional","affiliation":[{"name":"Centre for Language and Speech Technologies and Applications, Universitat Polit\u00e8cnica de Catalunya (UPC-TALP), 08034 Barcelona, Spain"}]},{"given":"Haixia","family":"Lyu","sequence":"additional","affiliation":[{"name":"GNSS Research Center, Wuhan University, Wuhan 430079, China"}]},{"given":"Victoria","family":"Graffigna","sequence":"additional","affiliation":[{"name":"UPC-IonSAT, Universitat Polit\u00e8cnica de Catalunya, 08034 Barcelona, Spain"},{"name":"Institut d\u2019Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8908-0972","authenticated-orcid":false,"given":"Estel","family":"Cardellach","sequence":"additional","affiliation":[{"name":"Institut d\u2019Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain"},{"name":"Institute of Space Science (ICE-CSIC), 08193 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5134-4901","authenticated-orcid":false,"given":"Mainul","family":"Hoque","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR), Institute for Solar-Terrestrial Physics, 17235 Neustrelitz, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7206-1705","authenticated-orcid":false,"given":"Fabricio S.","family":"Prol","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR), Institute for Solar-Terrestrial Physics, 17235 Neustrelitz, Germany"},{"name":"Department of Navigation and Positioning, Finnish Geospatial Research Institute, 02150 Espoo, Finland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7403-0208","authenticated-orcid":false,"given":"Riccardo","family":"Notarpietro","sequence":"additional","affiliation":[{"name":"European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), 64295 Darmstadt, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4844-6004","authenticated-orcid":false,"given":"Miquel","family":"Garcia-Fernandez","sequence":"additional","affiliation":[{"name":"Rokubun S.L., 08018 Barcelona, Spain"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2473","DOI":"10.1029\/2000GL000032","article-title":"Improving the Abel inversion by adding ground GPS data to LEO radio occultations in ionospheric sounding","volume":"27","author":"Juan","year":"2000","journal-title":"Geophys. Res. Lett."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"95-1","DOI":"10.1029\/2001GL014364","article-title":"GPS radio occultation measurements of the ionosphere from CHAMP: Early results","volume":"29","author":"Jakowski","year":"2002","journal-title":"Geophys. Res. Lett."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"7932","DOI":"10.1002\/2016JA022337","article-title":"A linear scale height Chapman model supported by GNSS occultation measurements","volume":"121","year":"2016","journal-title":"J. Geophys. Res. Space Phys."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1024","DOI":"10.1029\/2018GL080412","article-title":"Sensing heavy precipitation with GNSS polarimetric radio occultations","volume":"46","author":"Cardellach","year":"2019","journal-title":"Geophys. Res. 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