{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:39:18Z","timestamp":1760243958018,"version":"build-2065373602"},"reference-count":14,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2009,1,20]],"date-time":"2009-01-20T00:00:00Z","timestamp":1232409600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Algorithms"],"abstract":"<jats:p>In this study different approaches based on multilayer perceptron neural networks are proposed and evaluated with the aim to retrieve tropospheric profiles by using GPS radio occultation data. We employed a data set of 445 occultations covering the land surface within the Tropics, split into desert and vegetation zone. The neural networks were trained with refractivity profiles as input computed from geometrical occultation parameters provided by the FORMOSAT-3\/COSMIC satellites, while the targets were the dry and wet refractivity profiles and the dry pressure profiles obtained from the contemporary European Centre for Medium-Range Weather Forecast data. Such a new retrieval algorithm was chosen to solve the atmospheric profiling problem without the constraint of an independent knowledge of one atmospheric parameter at each GPS occultation.<\/jats:p>","DOI":"10.3390\/a2010031","type":"journal-article","created":{"date-parts":[[2009,1,20]],"date-time":"2009-01-20T10:54:04Z","timestamp":1232448844000},"page":"31-45","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Comparison of Different Neural Network Approaches for the Tropospheric Profiling over the Inter-tropical lands Using GPS Radio Occultation Data"],"prefix":"10.3390","volume":"2","author":[{"given":"Stefania","family":"Bonafoni","sequence":"first","affiliation":[{"name":"Dept. of Electronic and Information Engineering, University of Perugia, via G. Duranti 93, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fabrizio","family":"Pelliccia","sequence":"additional","affiliation":[{"name":"Dept. of Electronic and Information Engineering, University of Perugia, via G. Duranti 93, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Roberta","family":"Anniballe","sequence":"additional","affiliation":[{"name":"Dept. of Electronic and Information Engineering, University of Perugia, via G. Duranti 93, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2009,1,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1175\/1520-0477(1996)077<0019:GSOTAF>2.0.CO;2","article-title":"GPS Sounding of the atmosphere from low Earth orbit: preliminary results","volume":"77","author":"Ware","year":"1996","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_2","first-page":"429","article-title":"Observing Earth\u2019s atmosphere with radio occultation measurements using the Global Positioning System","volume":"102, D19","author":"Kursinski","year":"1997","journal-title":"J. Geophys. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1031","DOI":"10.1175\/1520-0477(2000)081<1031:ROWVPF>2.3.CO;2","article-title":"Retrieval of Water Vapor Profiles from GPS\/MET Radio Occultations","volume":"81","author":"Hermann","year":"2000","journal-title":"Bull. Am. Metereol. Soc."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"115","DOI":"10.3319\/TAO.2000.11.1.115(COSMIC)","article-title":"Applications of COSMIC to meteorology and climate","volume":"11","author":"Anthes","year":"2000","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1113","DOI":"10.1029\/2000JD900421","article-title":"A comparison of water vapour derived from GPS occultations and global weather analyses","volume":"106, D1","author":"Kursinski","year":"2001","journal-title":"J. Geophys. Res."},{"key":"ref_6","first-page":"1","article-title":"Observations and simulations of receiver-induced refractivity biases in GPS radio occultation","volume":"111, D12","author":"Beyerle","year":"2006","journal-title":"J. Geophys. Res."},{"key":"ref_7","unstructured":"http:\/\/www.cosmic.ucar.edu\/index.html."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1086\/111096","article-title":"The Neutral Atmosphere of Venus as Studied with the Mariner V Radio Occultation Experiments","volume":"76","author":"Fjeldbo","year":"1971","journal-title":"Astron. 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Math."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"989","DOI":"10.1109\/72.329697","article-title":"Training feed-forward networks with the Marquardt algorithm","volume":"5","author":"Hagan","year":"1994","journal-title":"IEEE Trans. Neural Networks"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1127","DOI":"10.1175\/1520-0469(1976)033<1127:TUOEOS>2.0.CO;2","article-title":"The use of eigenvectors of statistical covariance matrices for interpreting satellite sounding radiometer observations","volume":"33","author":"Smith","year":"1976","journal-title":"J. Atmos. 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