{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T16:16:21Z","timestamp":1774973781331,"version":"3.50.1"},"reference-count":40,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2020,7,31]],"date-time":"2020-07-31T00:00:00Z","timestamp":1596153600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000844","name":"European Space Agency","doi-asserted-by":"publisher","award":["5401002930 (Assumptions on Ionospheric Residuals, AIR)."],"award-info":[{"award-number":["5401002930 (Assumptions on Ionospheric Residuals, AIR)."]}],"id":[{"id":"10.13039\/501100000844","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V","award":["ZT-0007 (ADVANTAGE, Advanced Technologies for Navigation and Geodesy)"],"award-info":[{"award-number":["ZT-0007 (ADVANTAGE, Advanced Technologies for Navigation and Geodesy)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The next generation of satellite-based augmentation systems (SBAS) will support aviation receivers that take advantage of the ionosphere-free dual-frequency combination. By combining signals of the L1 and L5 bands, about 99% of the ionospheric refraction effects on the GNSS (Global Navigation Satellite Systems) signals can be removed in the user receivers without additional SBAS corrections. Nevertheless, even if most of the negative impacts on GNSS signals are removed by the ionospheric-free combination, some residuals remain and have to be taken into account by overbounding models in the integrity computation conducted by safety-of-live (SoL) receivers in airplanes. Such models have to overbound residuals as well, which result from the most rare extreme ionospheric events, e.g., such as the famous \u201cHalloween Storm\u201d, and should thus include the tails of the error distribution. Their application shall lead to safe error bounds on the user position and allow the computation of protection levels for the horizontal and vertical position errors. Here, we propose and justify such an overbounding model for residual ionospheric delays that remain after the application of the ionospheric-free linear combination. The model takes into account second- and third-order ionospheric refraction effects, excess path due to ray bending, and increased ionospheric total electron content (TEC) along the signal path due to ray bending.<\/jats:p>","DOI":"10.3390\/rs12152467","type":"journal-article","created":{"date-parts":[[2020,8,3]],"date-time":"2020-08-03T06:16:47Z","timestamp":1596435407000},"page":"2467","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["An SBAS Integrity Model to Overbound Residuals of Higher-Order Ionospheric Effects in the Ionosphere-Free Linear Combination"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0767-9418","authenticated-orcid":false,"given":"Stefan","family":"Schl\u00fcter","sequence":"first","affiliation":[{"name":"Galileo Competence Center, German Aerospace Center, Kalkhorstweg 53, 17235 Neustrelitz, Germany"}]},{"given":"Mohammed Mainul","family":"Hoque","sequence":"additional","affiliation":[{"name":"Institute for Solar-Terrestrial Physics, German Aerospace Center, Kalkhorstweg 53, 17235 Neustrelitz, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2020,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Juan, J.M., Sanz, S., Gonz\u00e1lez-Casado, G., Rovira-Garcia, A., Camps, A., Riba, J., Barbosa, J., Blanch, E., Altadill, D., and Orus, R. 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