{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2024,8,7]],"date-time":"2024-08-07T21:13:25Z","timestamp":1723065205309},"reference-count":67,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2019,6,11]],"date-time":"2019-06-11T00:00:00Z","timestamp":1560211200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"To facilitate F2-layer peak density (NmF2) modeling, a nonlinear polynomial model approach based on global NmF2 observational data from ionospheric radio occultation (IRO) measurements onboard the CHAMP, GRACE, and COSMIC satellites, is presented in this paper. We divided the globe into 63 slices from 80\u00b0S to 80\u00b0N according to geomagnetic latitude. A Nonlinear Polynomial Peak Density Model (NPPDM) was constructed by a multivariable least squares fitting to NmF2 measurements in each latitude slice and the dependencies of NmF2 on solar activity, geographical longitude, universal time, and day of year were described. The model was designed for quiet and moderate geomagnetic conditions (Ap \u2264 32). Using independent radio occultation data, quantitative analysis was made. The correlation coefficients between NPPDM predictions and IRO data were 0.91 in 2002 and 0.82 in 2005. The results show that NPPDM performs better than IRI2016 and Neustrelitz Peak Density Model (NPDM) under low solar activity, while it undergoes performance degradation under high solar activity. Using data from twelve ionosonde stations, the accuracy of NPPDM was found to be better than that of NPDM and comparable to that of IRI2016. Additionally, NPPDM can well simulate the variations and distributions of NmF2 and describe some ionospheric features, including the equatorial ionization anomaly, the mid-latitude trough, and the wavenumber-four longitudinal structure.<\/jats:p>","DOI":"10.3390\/rs11111386","type":"journal-article","created":{"date-parts":[[2019,6,11]],"date-time":"2019-06-11T14:55:44Z","timestamp":1560264944000},"page":"1386","source":"Crossref","is-referenced-by-count":9,"title":["A New Empirical Model of NmF2 Based on CHAMP, GRACE, and COSMIC Radio Occultation"],"prefix":"10.3390","volume":"11","author":[{"given":"Zhendi","family":"Liu","sequence":"first","affiliation":[{"name":"Institute of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China"}]},{"given":"Hanxian","family":"Fang","sequence":"additional","affiliation":[{"name":"Institute of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China"},{"name":"State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190, China"}]},{"given":"M. M.","family":"Hoque","sequence":"additional","affiliation":[{"name":"Institute of Communications and Navigation, German Aerospace Center, Kalkhorstweg 53, 17235 Neustrelitz, Germany"}]},{"given":"Libin","family":"Weng","sequence":"additional","affiliation":[{"name":"Institute of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China"}]},{"given":"Shenggao","family":"Yang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Astronautic Dynamics, Xi\u2019an Satellite Control Center, Xi\u2019an 710043, China"}]},{"given":"Ze","family":"Gao","sequence":"additional","affiliation":[{"name":"Institute of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Davies, K. (1990). 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