{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:16:22Z","timestamp":1760148982671,"version":"build-2065373602"},"reference-count":19,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,6,15]],"date-time":"2023-06-15T00:00:00Z","timestamp":1686787200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"EUMETSAT","award":["EUM\/CO\/21\/4600002530\/RN"],"award-info":[{"award-number":["EUM\/CO\/21\/4600002530\/RN"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>We conducted a study to assess the GNSS (Global Navigation Satellite System) Receiver for Atmospheric Sounding (GRAS) ionospheric data quality by processing Radio Occultation (RO) observations of ionospheric products. The main objective of the study is to validate ionospheric data generated at EUMETSAT, such as ionospheric bending angle profiles, amplitude and phase scintillations, topside Total Electron Content (TEC) from MetOp-A GRAS instrument as well as generating and validating new ionospheric products derived from GRAS RO observations such as the TEC, rate of TEC and vertical electron density profiles. The assessment is conducted by comparing and evaluating the systematic differences between similar products from other Low Earth Orbit (LEO) satellite missions or from ground-based ionospheric measurements. The study confirms that the GNSS topside and RO observations recorded by the GRAS instrument onboard MetOp satellites are of good quality and are a valuable source of data for ionospheric research.<\/jats:p>","DOI":"10.3390\/rs15123129","type":"journal-article","created":{"date-parts":[[2023,6,16]],"date-time":"2023-06-16T02:02:20Z","timestamp":1686880940000},"page":"3129","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Assessment of GRAS Ionospheric Measurements for Ionospheric Model Assimilation"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5134-4901","authenticated-orcid":false,"given":"M. M.","family":"Hoque","sequence":"first","affiliation":[{"name":"German Aerospace Center (DLR), Institute for Solar-Terrestrial Physics, Kalkhorstweg 53, 17235 Neustrelitz, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7206-1705","authenticated-orcid":false,"given":"F. S.","family":"Prol","sequence":"additional","affiliation":[{"name":"Department of Navigation and Positioning, Finnish Geospatial Research Institute (FGI), National Land Survey of Finland (NLS), Vuorimiehentie 5, 02150 Espoo, Finland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9687-5850","authenticated-orcid":false,"given":"M.","family":"Hernandez-Pajares","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Universitat Polit\u00e8cnica de Catalunya\u2014Ionospheric Determination and Navigation Based on Satellite and Terrestrial Systems (UPC-IonSAT), IEEC-UPC, E08034 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7403-0208","authenticated-orcid":false,"given":"R.","family":"Notarpietro","sequence":"additional","affiliation":[{"name":"European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), 64293 Darmstadt, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6711-107X","authenticated-orcid":false,"given":"L.","family":"Yuan","sequence":"additional","affiliation":[{"name":"German Aerospace Center (DLR), Institute for Solar-Terrestrial Physics, Kalkhorstweg 53, 17235 Neustrelitz, Germany"}]},{"given":"G.","family":"Olivares-Pulido","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Universitat Polit\u00e8cnica de Catalunya\u2014Ionospheric Determination and Navigation Based on Satellite and Terrestrial Systems (UPC-IonSAT), IEEC-UPC, E08034 Barcelona, Spain"}]},{"given":"V.","family":"Graffigna","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Universitat Polit\u00e8cnica de Catalunya\u2014Ionospheric Determination and Navigation Based on Satellite and Terrestrial Systems (UPC-IonSAT), IEEC-UPC, E08034 Barcelona, Spain"}]},{"given":"A.","family":"Von Engeln","sequence":"additional","affiliation":[{"name":"European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), 64293 Darmstadt, Germany"}]},{"given":"C.","family":"Marquardt","sequence":"additional","affiliation":[{"name":"European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), 64293 Darmstadt, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1085","DOI":"10.1175\/BAMS-88-7-1085","article-title":"An introduction to the EUMETSAT Polar System","volume":"88","author":"Klaes","year":"2007","journal-title":"Bull. 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