{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:29:44Z","timestamp":1760239784722,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2020,12,16]],"date-time":"2020-12-16T00:00:00Z","timestamp":1608076800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["HO 6136\/1-1"],"award-info":[{"award-number":["HO 6136\/1-1"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>At some locations, especially in the auroral regions, the ionization of the E layer can dominate over that of the F2 layer, which is called the E layer dominated ionosphere (ELDI). In the present work we investigate the spatiotemporal variation of the ELDI depending on the season, solar activity, geomagnetic activity, interplanetary magnetic field, convection electric field, and solar wind energy. We specify each distribution of ELDI events by the values of four parameters. In this regard, we compute the height, full width at half maximum, and position of a Gaussian function relative to a precomputed reference ellipse as parameters to describe the spatial distribution of ELDI events in geocentric latitude\/longitude coordinates. To study the temporal variation of the ELDI events, we estimate the weighted mean local time of the distribution as the fourth parameter. The database used for our investigations contains more than 3.5 million vertical electron density profiles derived from ionospheric GPS radio occultation observations on board the COSMIC\/FORMOSAT-3 (Constellation Observing System for Meteorology, Ionosphere, and Climate\/Formosa Satellite Mission 3) mission, covering a period of almost 13 years. The analysis of observations representing changing geophysical conditions results in clear trends for all ELDI parameters. In this context, the mean local time varies mostly between 01:00 and 02:00 local time, while the probability of ELDI occurrence is increased in local winter and in the case of low solar activity. Likewise, an increase in the solar wind parameters increases the number of ELDI events and leads to an equatorward shift of their position. The relationships found in our investigations can serve as a basis for future modeling studies addressing ELDI occurrences as a function of selected geophysical quantities.<\/jats:p>","DOI":"10.3390\/rs12244109","type":"journal-article","created":{"date-parts":[[2020,12,16]],"date-time":"2020-12-16T09:21:15Z","timestamp":1608110475000},"page":"4109","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["E Layer Dominated Ionosphere Occurrences as a Function of Geophysical and Space Weather Conditions"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6756-9803","authenticated-orcid":false,"given":"Sumon","family":"Kamal","sequence":"first","affiliation":[{"name":"Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), 17235 Neustrelitz, Germany"},{"name":"Institute of Geodesy and Geoinformation Science, Technische Universit\u00e4t Berlin, 10623 Berlin, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3174-2624","authenticated-orcid":false,"given":"Norbert","family":"Jakowski","sequence":"additional","affiliation":[{"name":"Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), 17235 Neustrelitz, Germany"}]},{"given":"Mohammed M.","family":"Hoque","sequence":"additional","affiliation":[{"name":"Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), 17235 Neustrelitz, Germany"}]},{"given":"Jens","family":"Wickert","sequence":"additional","affiliation":[{"name":"Institute of Geodesy and Geoinformation Science, Technische Universit\u00e4t Berlin, 10623 Berlin, Germany"},{"name":"German Research Centre for Geosciences (GFZ), 14473 Potsdam, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1207","DOI":"10.5194\/angeo-27-1207-2009","article-title":"Enhanced E-layer ionization in the auroral zones observed by radio occultation measurements onboard CHAMP and Formosat-3\/COSMIC","volume":"27","author":"Mayer","year":"2009","journal-title":"Ann. Geophys."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Reigber, C., L\u00fchr, H., Schwintzer, P., and Wickert, J. (2005). Earth Observation with CHAMP: Results from Three Years in Orbit, Springer.","DOI":"10.1007\/b138105"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1223","DOI":"10.5194\/angeo-32-1223-2014","article-title":"E layer dominated ionosphere observed by EISCAT\/ESR radars during solar minimum","volume":"32","author":"Cai","year":"2014","journal-title":"Ann. Geophys."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2789","DOI":"10.5194\/amt-8-2789-2015","article-title":"Use of radio occultation to probe the high-latitude ionosphere","volume":"8","author":"Mannucci","year":"2015","journal-title":"Atmos. Meas. Tech."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Kamal, S., Jakowski, N., Hoque, M.M., and Wickert, J. (2020). Evaluation of E Layer Dominated Ionosphere Events Using COSMIC\/FORMOSAT-3 and CHAMP Ionospheric Radio Occultation Data. Remote Sens., 12.","DOI":"10.3390\/rs12020333"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/0032-0633(67)90190-0","article-title":"Dynamics of auroral belt and polar geomagnetic disturbances","volume":"15","author":"Feldstein","year":"1967","journal-title":"Planet. Space Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1029\/GL002i009p00377","article-title":"Mathematical representation of the auroral oval","volume":"2","author":"Holzworth","year":"1975","journal-title":"Geophys. Res. Lett."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Carbary, J.F. (2005). A Kp-based model of auroral boundaries. Space Weather, 3.","DOI":"10.1029\/2005SW000162"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"623","DOI":"10.5194\/angeo-32-623-2014","article-title":"An empirical model of the auroral oval derived from CHAMP field-aligned current signatures\u2014Part 2","volume":"32","author":"Xiong","year":"2014","journal-title":"Ann. Geophys."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Newell, P.T., Sotirelis, T., Liou, K., Meng, C.-I., and Rich, F.J. (2007). A nearly universal solar wind-magnetosphere coupling function inferred from 10 magnetospheric state variables. J. Geophys. Res., 112.","DOI":"10.1029\/2006JA012015"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1175\/BAMS-89-3-313","article-title":"The COSMIC\/FORMOSAT-3 mission: Early results","volume":"89","author":"Anthes","year":"2008","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_12","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_13","doi-asserted-by":"crossref","first-page":"3813","DOI":"10.1109\/TGRS.2007.903365","article-title":"FORMOSAT-3\/COSMIC GPS Radio Occultation Mission: Preliminary Results","volume":"45","author":"Liou","year":"2007","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_14","unstructured":"CDAAC (2020, December 15). COSMIC Data Analysis and Archive Center. Available online: https:\/\/cdaac-www.cosmic.ucar.edu\/."},{"key":"ref_15","unstructured":"SPDF (2020, December 15). OMNIWeb Service, Available online: https:\/\/omniweb.gsfc.nasa.gov\/."},{"key":"ref_16","unstructured":"Kelley, M.C. (2009). The Earth's Ionosphere: Plasma Physics and Electrodynamics, Academic Press. [2nd ed.]."},{"key":"ref_17","unstructured":"WDC (2020, December 15). Magnetic North, Geomagnetic and Magnetic Poles. Available online: http:\/\/wdc.kugi.kyoto-u.ac.jp\/poles\/polesexp.html."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1016\/j.jastp.2017.08.006","article-title":"Estimation of ionospheric sporadic E intensities from GPS radio occultation","volume":"171","author":"Arras","year":"2018","journal-title":"J. Atmos. Sol.-Terr. Phys."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Wu, D.L., Ao, C.O., Hajj, G.A., de la Torre Juarez, M., and Mannucci, A.J. (2005). Sporadic E morphology from GPS-CHAMP radio occultation. J. Geophys. Res., 110.","DOI":"10.1029\/2004JA010701"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1007\/BF00215692","article-title":"Recent progress in studies of DMSP auroral photographs","volume":"19","author":"Akasofu","year":"1976","journal-title":"Space Sci. Rev."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"857","DOI":"10.1016\/0032-0633(73)90102-5","article-title":"The diffuse aurora","volume":"21","author":"Lui","year":"1973","journal-title":"Planet. Space Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"799","DOI":"10.1016\/0032-0633(73)90097-4","article-title":"A uniform belt of diffuse auroral emission seen by the ISIS-2 scanning photometer","volume":"21","author":"Lui","year":"1973","journal-title":"Planet. Space Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1007\/PL00012820","article-title":"Eye on the Ionosphere: The Correlation between Solar 10.7 cm Radio Flux and Ionospheric Range Delay","volume":"3","author":"Doherty","year":"2000","journal-title":"GPS Solut."},{"key":"ref_24","first-page":"7","article-title":"Hourly values of equatorial Dst for the IGY","volume":"Volume 35","author":"Sugiura","year":"1964","journal-title":"Annals of the International Geophysical Year"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"785","DOI":"10.1029\/JZ071i003p00785","article-title":"Auroral electrojet activity index AE and its universal time variations","volume":"71","author":"Davis","year":"1966","journal-title":"J. Geophys. Res."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2913","DOI":"10.5194\/angeo-27-2913-2009","article-title":"Influences on the radius of the auroral oval","volume":"27","author":"Milan","year":"2009","journal-title":"Ann. Geophys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"566","DOI":"10.1007\/s00585-998-0566-z","article-title":"The size of the auroral belt during magnetic storms","volume":"16","author":"Yokoyama","year":"1998","journal-title":"Ann. Geophys."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"5771","DOI":"10.1029\/93JA02867","article-title":"What is a geomagnetic storm?","volume":"99","author":"Gonzalez","year":"1994","journal-title":"J. Geophys. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1023\/A:1005160129098","article-title":"Interplanetary origin of geomagnetic storms","volume":"88","author":"Gonzalez","year":"1999","journal-title":"Space Sci. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1103\/PhysRevLett.6.47","article-title":"Interplanetary Magnetic Field and the Auroral Zones","volume":"6","author":"Dungey","year":"1961","journal-title":"Phys. Rev. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1007\/s11214-010-9629-z","article-title":"Current Systems in Planetary Magnetospheres and Ionospheres","volume":"152","author":"Baumjohann","year":"2010","journal-title":"Space Sci. Rev."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1007\/s11214-017-0333-0","article-title":"Overview of Solar Wind\u2013Magnetosphere\u2013Ionosphere\u2013Atmosphere Coupling and the Generation of Magnetospheric Currents","volume":"206","author":"Milan","year":"2017","journal-title":"Space Sci. Rev."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/24\/4109\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:45:47Z","timestamp":1760179547000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/24\/4109"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,12,16]]},"references-count":32,"journal-issue":{"issue":"24","published-online":{"date-parts":[[2020,12]]}},"alternative-id":["rs12244109"],"URL":"https:\/\/doi.org\/10.3390\/rs12244109","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2020,12,16]]}}}