{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,23]],"date-time":"2025-10-23T05:38:42Z","timestamp":1761197922680,"version":"build-2065373602"},"reference-count":28,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,23]],"date-time":"2021-02-23T00:00:00Z","timestamp":1614038400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Global navigation satellite system (GNSS) can provide dual-frequency observation data, which can be used to effectively calculate total electron content (TEC). Numerical studies have utilized GNSS-derived TEC to evaluate the accuracy of ionospheric empirical models, such as the International Reference Ionosphere model (IRI) and the NeQuick model. However, most studies have evaluated vertical TEC rather than slant TEC (STEC), which resulted in the introduction of projection error. Furthermore, since there are few GNSS observation stations available in the Antarctic region and most are concentrated in the Antarctic continent edge, it is difficult to evaluate modeling accuracy within the entire Antarctic range. Considering these problems, in this study, GNSS STEC was calculated using dual-frequency observation data from stations that almost covered the Antarctic continent. By comparison with GNSS STEC, the accuracy of IRI-2016 and NeQuick2 at different latitudes and different solar radiation was evaluated during 2016\u20132017. The numerical results showed the following. (1) Both IRI-2016 and NeQuick2 underestimated the STEC. Since IRI-2016 utilizes new models to represent the F2-peak height (hmF2) directly, the IRI-2016 STEC is closer to GNSS STEC than NeQuick2. This conclusion was also confirmed by the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) occultation data. (2) The differences in STEC of the two models are both normally distributed, and the NeQuick2 STEC is systematically biased as solar radiation increases. (3) The root mean square error (RMSE) of the IRI-2016 STEC is smaller than that of the NeQuick2 model, and the RMSE of the two modeling STEC increases with solar radiation intensity. Since IRI-2016 relies on new hmF2 models, it is more stable than NeQuick2.<\/jats:p>","DOI":"10.3390\/s21041551","type":"journal-article","created":{"date-parts":[[2021,2,23]],"date-time":"2021-02-23T20:19:36Z","timestamp":1614111576000},"page":"1551","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Accuracy Analysis of International Reference Ionosphere 2016 and NeQuick2 in the Antarctic"],"prefix":"10.3390","volume":"21","author":[{"given":"Zihuai","family":"Guo","sequence":"first","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7723-4601","authenticated-orcid":false,"given":"Yibin","family":"Yao","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"},{"name":"Key Laboratory of Geospace Enviroment and Geodesy, Ministry of Education, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan 430079, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jian","family":"Kong","sequence":"additional","affiliation":[{"name":"Chinese Antarctic Center of Surveying and Mapping, Wuhan 430079, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gang","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2692-9451","authenticated-orcid":false,"given":"Chen","family":"Zhou","sequence":"additional","affiliation":[{"name":"School of Electronic Information, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qi","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lulu","family":"Shan","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chen","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1016\/j.asr.2017.01.006","article-title":"Comparison of midlatitude ionospheric F region peak parameters and topside Ne profiles from IRI2012 model prediction with ground-based ionosonde and Alouette II observations","volume":"60","author":"Gordiyenko","year":"2017","journal-title":"Adv. Space Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2010RS004635","article-title":"Data ingestion into NeQuick 2","volume":"46","author":"Nava","year":"2011","journal-title":"Radio Sci."},{"key":"ref_3","unstructured":"She, L.L., Bai, W.H., Sun, Y.Q., Tian, Y.S., Meng, X.G., and Du, Q.F. (2018, January 14\u201322). Error Analysis on NmF2 and HmF2 of IRI-2016 model Model during Magnetically Quiet and Storm Periods. Proceedings of the 42nd COSPAR Scientific Assembly, Pasadena, CA, USA."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1457","DOI":"10.2478\/s11600-013-0116-2","article-title":"Assessment of NeQuick ionospheric model for Galileo single-frequency users","volume":"61","author":"Angrisano","year":"2013","journal-title":"Acta Geophys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1756","DOI":"10.1016\/j.asr.2012.11.018","article-title":"Global Empirical Models of the Density Peak Height and of the Equivalent Scale Height for Quiet Conditions","volume":"52","author":"Altadill","year":"2012","journal-title":"Adv. Space Res."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1016\/j.jastp.2013.08.024","article-title":"Global model of the F2 layer peak height for low solar activity based on GPS radio-occultation data","volume":"104","author":"Shubin","year":"2013","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1856","DOI":"10.1016\/j.jastp.2008.01.015","article-title":"A new version of the NeQuick ionosphere electron density model","volume":"70","author":"Nava","year":"2008","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_8","first-page":"17G20","article-title":"Accuracy comparison and analysis between Galileo ionospheric correction models","volume":"40","author":"Wu","year":"2015","journal-title":"Surv. Land Inf. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/0273-1177(90)90301-F","article-title":"An analytical model of the electron density profile in the ionosphere","volume":"10","author":"Giovanni","year":"1990","journal-title":"Adv. Space Res."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Radicella, S.M., and Zhang, M.L. (1995). The improved DGR analytical model of electron density height profile and total electron content in the ionosphere. Ann. Geophys., 38.","DOI":"10.4401\/ag-4130"},{"key":"ref_11","first-page":"421","article-title":"Performance Analysis of Different NeQuick Ionospheric Model Parameters","volume":"46","author":"Wang","year":"2017","journal-title":"Acta Geod. et Cartogr. Sin."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"752","DOI":"10.1002\/2015RS005905","article-title":"NeQuick and IRI-Plas model performance on topside electron content representation: Spaceborne GPS measurements","volume":"51","author":"Cherniak","year":"2016","journal-title":"Radio Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5087","DOI":"10.1002\/2014JA019960","article-title":"On the performance of the IRI-2012 and NeQuick2 models during the increasing phase of the unusual 24th solar cycle in the Brazilian equatorial and low-latitude sectors","volume":"119","author":"Venkatesh","year":"2014","journal-title":"J. Geophys. Res.-Space"},{"key":"ref_14","first-page":"1","article-title":"The research of IRI, NeQuick and Klobuchar models","volume":"27","author":"Fang","year":"2012","journal-title":"Prog. Geophys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e2019SW002422","DOI":"10.1029\/2019SW002422","article-title":"Assessment and Validation of Three Ionospheric Models (IRI-2016, NeQuick2, and IGS-GIM) From 2002 to 2018","volume":"18","author":"Chen","year":"2020","journal-title":"Space Weather"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jastp.2018.02.006","article-title":"Assessment of the NeQuick-2 and IRI-Plas 2017 models using global and long-term GNSS measurements","volume":"170","author":"Okoh","year":"2018","journal-title":"J. Atmos. Sol. Terr. Phys."},{"key":"ref_17","first-page":"18","article-title":"Pattern of the variation of the TEC extracted from the GPS, IRI 2016, IRI-Plas 2017 and NeQuick 2 over polar region","volume":"25","author":"Tariku","year":"2020","journal-title":"Antarct. Life Sci. Space Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1007\/s00190-008-0300-3","article-title":"The International GNSS Service in a changing landscape of Global Navigation Satellite Systems","volume":"83","author":"Dow","year":"2009","journal-title":"J. Geod."},{"key":"ref_19","first-page":"157","article-title":"Analysis of the global ionospheric disturbances of the March 2015 great storm","volume":"121","author":"Yao","year":"2016","journal-title":"J. Geophys. Res.-Space"},{"key":"ref_20","first-page":"1022","article-title":"Extraction of regional ionospheric TEC from GPS dual observation","volume":"39","author":"Nie","year":"2014","journal-title":"Geomat. Inf. Sci. Wuhan Univ."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"168","DOI":"10.11728\/cjss2014.02.168","article-title":"Derivation of TEC and GPS Hardware Delay Based on Dual-frequency GPS Observations","volume":"34","author":"Wang","year":"2014","journal-title":"Chin. J. Space Sci."},{"key":"ref_22","first-page":"1186","article-title":"Modeling Global Ionospheric Delay with IGS Ground-Based GNSS Observations","volume":"37","author":"Zhang","year":"2012","journal-title":"Geomat. Inf. Sci. Wuhan Univ."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1017\/S0954102016000602","article-title":"NeQuick2 and IRI2012 models applied to mid and high latitudes, and the Antarctic ionosphere","volume":"29","author":"Pietrella","year":"2017","journal-title":"Antarct. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"21","DOI":"10.3319\/TAO.2000.11.1.21(COSMIC)","article-title":"COSMIC System Description","volume":"11","author":"Rocken","year":"2000","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1029\/97RS03183","article-title":"Ionospheric electron density profiles obtained with the Global Positioning System: Results from the GPS\/MET experiment","volume":"33","author":"Hajj","year":"1998","journal-title":"Radio Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"951","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_27","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1134\/S0016793214030116","article-title":"Magnetic disturbance generation during the historic magnetic storm in September 1859","volume":"54","author":"Levitin","year":"2014","journal-title":"Geomag. Aeron."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1221","DOI":"10.1002\/2016JA023375","article-title":"Modeling the plasmasphere based on LEO satellites onboard GPS measurements","volume":"122","author":"Chen","year":"2017","journal-title":"J. Geophys. Res.-Space"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/4\/1551\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:27:09Z","timestamp":1760160429000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/4\/1551"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,2,23]]},"references-count":28,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2021,2]]}},"alternative-id":["s21041551"],"URL":"https:\/\/doi.org\/10.3390\/s21041551","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2021,2,23]]}}}