{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,20]],"date-time":"2026-02-20T23:20:44Z","timestamp":1771629644907,"version":"3.50.1"},"reference-count":67,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2022,4,9]],"date-time":"2022-04-09T00:00:00Z","timestamp":1649462400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Strategic Priority Research Program of Chinese Academy of Sciences: XDB","award":["41000000"],"award-info":[{"award-number":["41000000"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42030202,42174204,41904140"],"award-info":[{"award-number":["42030202,42174204,41904140"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The Martian ionosphere was actively detected by Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) aboard the Mars Express. The detected echo signal of the MARSIS at an epoch is presented as a function of frequency and time delay to form an ionogram. Some MARSIS ionograms have been processed to obtain the electron density profiles of the Martian topside ionosphere. Unfortunately, more than half of the records cannot be processed with current methods due to the lack of local plasma density information at spacecraft altitude. In this work, we employ a piece-wise exponent to describe the electron density profile of the Martian topside ionosphere. The piece-wise exponent used in our method can reasonably capture the altitude structure of the Martian topside ionosphere, which has been validated with the MGS and MAVEN data. In an altitude regime of lower than 200 km, the average absolute height error of the same electron density between MGS data and fitted profiles is 0.006 km, and the average relative error is 0.008%. In an altitude regime of higher than 200 km, the average absolute height error of the same electron density between MGS data and fitted profiles is 0.55 km, and the average relative error is \u22120.1%. Based on the altitude structure knowledge of the Martian topside ionosphere, we put forward a new method to invert electron density profiles from MARSIS ionograms with\/without local plasma density information. Compared with the previous results, the average absolute difference in the peak height of the retrieved profile is 7.38 km, within the margin of the MARSIS height resolution of 13.8 km. The average relative difference is only 3%. The application of the new method can greatly improve the utilization rate of MARSIS ionogram records.<\/jats:p>","DOI":"10.3390\/rs14081817","type":"journal-article","created":{"date-parts":[[2022,4,10]],"date-time":"2022-04-10T06:02:54Z","timestamp":1649570574000},"page":"1817","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["A New Method for Retrieving Electron Density Profiles from the MARSIS Ionograms"],"prefix":"10.3390","volume":"14","author":[{"given":"Wendong","family":"Liu","sequence":"first","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5773-0184","authenticated-orcid":false,"given":"Libo","family":"Liu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Yiding","family":"Chen","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5989-1720","authenticated-orcid":false,"given":"Huijun","family":"Le","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Ruilong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5592-728X","authenticated-orcid":false,"given":"Wenbo","family":"Li","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Jiacheng","family":"Li","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Tongtong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Yuyan","family":"Yang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Han","family":"Ma","sequence":"additional","affiliation":[{"name":"Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China"},{"name":"College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1088\/0959-5309\/43\/1\/305","article-title":"The absorption and dissociative or ionizing effect of monochromatic radiation in an atmosphere on a rotating Earth","volume":"43","author":"Chapman","year":"1931","journal-title":"Proc. Phys. Soc."},{"key":"ref_2","first-page":"621","article-title":"On some direct evidence for downward atmospheric reflection of electric rays","volume":"109","author":"Appleton","year":"1925","journal-title":"Proc. Phys. Soc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"554","DOI":"10.1103\/PhysRev.28.554","article-title":"A test of the existence of the conducting layer","volume":"28","author":"Breit","year":"1926","journal-title":"Phys. Rev."},{"key":"ref_4","first-page":"528","article-title":"Review of Venusian and Martian ionospheres","volume":"52","author":"Cao","year":"2021","journal-title":"Rev. Geophys. Planet. Phys."},{"key":"ref_5","first-page":"1090","article-title":"The intrinsic magnetic field and solar-wind interaction of Mars","volume":"1","author":"Luhmann","year":"1992","journal-title":"Mars"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"323","DOI":"10.11728\/cjss2011.03.323","article-title":"Detection of Martian ionosphere","volume":"31","author":"Zou","year":"2011","journal-title":"Chin. J. Space Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1463","DOI":"10.1029\/2000JE001291","article-title":"Radio Occultation Measurements of Forced Atmospheric Waves on Mars","volume":"106","author":"Hinson","year":"2001","journal-title":"J. Geophys. Res."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"8958","DOI":"10.1002\/2015GL066146","article-title":"First measurements of composition and dynamics of the Martian ionosphere by MAVEN\u2019s neutral gas and ion mass spectrometer","volume":"42","author":"Benna","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_9","unstructured":"Chicarro, A., Martin, P., and Trautner, R. (2004). Mars Express: A European Mission to the Red Planet, European Space Agency Publication Division. [1st ed.]."},{"key":"ref_10","unstructured":"Picardi, G., Sorge, S., Seu, R., Plaut, J., Johnson, W., Jordan, R., Gurnett, D., Orosei, R., Borgarelli, L., and Braconi, G. (July, January 28). The Mars advanced radar for subsurface and ionosphere sounding (MARSIS): Concept and performance. Proceedings of the Geoscience and Remote Sensing Symposium, Humburg, Germany."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1975","DOI":"10.1016\/j.pss.2009.09.016","article-title":"The Mars Express MARSIS sounder instrument","volume":"57","author":"Jordan","year":"2009","journal-title":"Planet. Space Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1186\/s40623-022-01582-w","article-title":"Concurrent effects of Martian topography on the thermosphere and ionosphere at high northern latitudes","volume":"74","author":"Chen","year":"2022","journal-title":"Earth Planets Space"},{"key":"ref_13","first-page":"A09303","article-title":"Variation of the Martian ionospheric electron density from Mars express radar soundings","volume":"113","author":"Morgan","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1002\/rds.20023","article-title":"The processing of electron density profiles from the Mars Express MARSIS topside sounder","volume":"48","author":"Morgan","year":"2013","journal-title":"Radio Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1335","DOI":"10.1016\/j.asr.2007.01.062","article-title":"An overview of radar soundings of the Martian ionosphere from the Mars Express spacecraft","volume":"41","author":"Gurnett","year":"2008","journal-title":"Adv. Space Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1391","DOI":"10.1016\/j.pss.2010.06.011","article-title":"Reconstruction of non-monotonic electron density profiles of the Martian topside ionosphere","volume":"58","author":"Zou","year":"2010","journal-title":"Planet. Space Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"753","DOI":"10.5047\/eps.2012.03.006","article-title":"Ionogram inversion for MARISI topside sounding","volume":"64","author":"Han","year":"2012","journal-title":"Earth Planets Space"},{"key":"ref_18","first-page":"A07302","article-title":"Electron densities in the upper ionosphere of Mars from the excitation of electron plasma oscillations","volume":"113","author":"Duru","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_19","unstructured":"Budden, K.G. (1988). The Propagation of Radio Waves: The Theory of Radio Waves of Low Power in the Ionosphere and Magnetosphere, Cambridge University Press. [1st ed.]."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1137\/S1052623496303470","article-title":"Convergence Properties of the Nelder-Mead Simplex Method in Low Dimensions","volume":"9","author":"Lagarias","year":"1998","journal-title":"SIAM J. Optim."},{"key":"ref_21","unstructured":"Whittaker, E.T., and Watson, G.N. (1927). A Course of Modern Analysis, Cambridge Univ. Press."},{"key":"ref_22","unstructured":"Thomas, J., and Vickers, M. (1959). The Conversion of Ionospheric Virtual Height-Frequency Curves to Electron Density-Height Profiles, HM Stationery Office. Radio Research Special Report No. 28."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"129","DOI":"10.3319\/TAO.1992.3.2.129(A)","article-title":"A study of the true height analysis methods","volume":"312","author":"Liu","year":"1992","journal-title":"Terr. Atmos. Ocean. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1088\/0959-5309\/41\/1\/305","article-title":"Some notes on wireless methods of investigating the electrical structure of the upper atmosphere I","volume":"41","author":"Appleton","year":"1928","journal-title":"Proc. Phys. Soc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1088\/0959-5309\/42\/4\/304","article-title":"Some notes on wireless methods of investigating the electrical structure of the upper atmosphere II","volume":"42","author":"Appleton","year":"1930","journal-title":"Proc. Phys. Soc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"518","DOI":"10.1088\/0959-5309\/52\/4\/311","article-title":"The application of ionospheric data to radio communication problems, Part, I","volume":"52","author":"Appleton","year":"1940","journal-title":"Proc. Phys. Soc."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1103\/PhysRev.57.87","article-title":"Relation between actual and virtual ionospheric height","volume":"57","author":"Booker","year":"1940","journal-title":"Phys. Rev."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1029\/JZ056i004p00463","article-title":"A quick method for analyzing ionospheric records","volume":"56","author":"Ratcliffe","year":"1951","journal-title":"J. Geophys. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1029\/JZ056i004p00487","article-title":"Some regularities in the F2 region of the ionosphere","volume":"56","author":"Ratcliffe","year":"1951","journal-title":"J. Geophys. Res."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1016\/0021-9169(56)90161-1","article-title":"The calculation of the true heights of reflection of radio waves\u00b7 in the ionosphere","volume":"4","author":"Beynon","year":"1956","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"698","DOI":"10.1103\/PhysRev.71.698","article-title":"The true height of an ionospheric layer","volume":"71","author":"Pierce","year":"1947","journal-title":"Phys. Rev."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/0021-9169(52)90068-8","article-title":"Group velocities and group heights from the magnetoionic theory","volume":"2","author":"Shinn","year":"1952","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"240","DOI":"10.1016\/0021-9169(53)90058-0","article-title":"The analysis of ionospheric records (ordinary ray) part I","volume":"4","author":"Shinn","year":"1953","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1080\/14786443009461605","article-title":"Some remarks on the analogy of certain cases of propagation of electromagnetic waves and the motion of a particle in a potential field","volume":"10","year":"1930","journal-title":"Phil. Mag."},{"key":"ref_35","first-page":"1203","article-title":"The determination of ionospheric electron density distribution","volume":"35","author":"Manning","year":"1947","journal-title":"Proc. Inst. Radio Engrs."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1029\/JZ057i003p00357","article-title":"A procedure for the determination of the virtual distribution of the electron density in the ionosphere","volume":"57","author":"Kelso","year":"1952","journal-title":"J. Geophys. Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/0021-9169(54)90004-5","article-title":"The determination of the electron density distribution of an ionospheric layer in the presence of an external magnetic field","volume":"5","author":"Kelso","year":"1954","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1016\/0021-9169(57)90144-7","article-title":"The calculation of ionospheric electron density distribution","volume":"10","author":"Kelso","year":"1957","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_39","unstructured":"Rydbeck, O.E.H. (1942). A Theoretical Survey of the Possibilities of Determining the Distribution of the Free Electrons in the Upper Atmosphere, Chalmers University of Technology. [3rd ed.]."},{"key":"ref_40","first-page":"1","article-title":"The reduction of h\u2019(f) records to electron density profile","volume":"94","author":"Schmerling","year":"1957","journal-title":"Ionosph. Res. Sci. Penn. State Univ."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/0021-9169(58)90003-5","article-title":"An easily applied method for the reduction of h\u2019(f) records to N(h) profiles including the effects of the Earth\u2019s magnetic field","volume":"12","author":"Schmerling","year":"1958","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"244","DOI":"10.1016\/S0021-9169(51)80005-9","article-title":"Determination of electron densities in the ionosphere from experimental h\u2019(f) curves","volume":"1","author":"Whale","year":"1951","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1103\/PhysRev.51.333","article-title":"Height of reflection of radio-waves in the ionosphere","volume":"51","author":"Murray","year":"1937","journal-title":"Phys. Rev."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1016\/0021-9169(54)90041-0","article-title":"Electron distribution in the ionosphere","volume":"5","author":"King","year":"1954","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1029\/JZ061i001p00107","article-title":"A new method for obtaining electron-density profiles from h\u2019(f) records","volume":"61","author":"Jackson","year":"1956","journal-title":"J. Geophys. Res."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/0021-9169(61)90185-4","article-title":"A new method for the analysis of ionospheric h\u2019(f) records","volume":"21","author":"Titheridge","year":"1961","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"1169","DOI":"10.1002\/rds19672101169","article-title":"The overlapping polynomial analysis of ionograms","volume":"2","author":"Titheridge","year":"1967","journal-title":"Radio Sci."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1029\/RS004i001p00041","article-title":"The single polynomial analysis of ionograms","volume":"3","author":"Titheridge","year":"1969","journal-title":"Radio Sci."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"589","DOI":"10.1029\/RS010i006p00589","article-title":"The relative accuracy of ionogram analysis techniques","volume":"10","author":"Titheridge","year":"1975","journal-title":"Radio Sci."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1029\/RS012i003p00451","article-title":"A least squares polynomial and its application to topside ionograms","volume":"12","author":"Titheridge","year":"1977","journal-title":"Radio Sci."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1016\/0021-9169(79)90108-9","article-title":"Increased accuracy with simple methods of ionogram analysis","volume":"41","author":"Titheridge","year":"1979","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1016\/0021-9169(86)90120-0","article-title":"Starting models for the real height analysis of ionograms","volume":"48","author":"Titheridge","year":"1986","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"831","DOI":"10.1029\/RS023i005p00831","article-title":"The real height analysis of ionogram: A generalized formulation","volume":"23","author":"Titheridge","year":"1988","journal-title":"Radio Sci."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/0021-9169(58)90007-2","article-title":"The electron distribution in the ionosphere over Slough\u2014I. Quiet days","volume":"12","author":"Thomas","year":"1958","journal-title":"J. Atmos. Terr. Phys."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"837","DOI":"10.1029\/RS017i004p00837","article-title":"Automatic calculation of electron density profiles from digital ionograms: 2. True height inversion of topside ionograms with the profile-fitting method","volume":"17","author":"Huang","year":"1982","journal-title":"Radio Sci."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1186\/BF03352022","article-title":"Automatic scaling of F2-layer parameters from ionograms based on the empirical orthogonal function (EOF) analysis of ionospheric electron density","volume":"59","author":"Ding","year":"2007","journal-title":"Earth Planets Space"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"1683","DOI":"10.1016\/j.asr.2008.08.017","article-title":"Reconstruction of topside density profile by using the topside sounder model profiler and digisonde data","volume":"43","author":"Kutiev","year":"2009","journal-title":"Adv. Space Res."},{"key":"ref_58","first-page":"1895","article-title":"Plasmaspheric electron density reconstruction based on the topside sounder model profiler","volume":"58","author":"Kutiev","year":"2009","journal-title":"Acta Geophys."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"A21","DOI":"10.1051\/swsc\/2012021","article-title":"Adjustments of the TaD electron density reconstruction model with GNSS-TEC parameters for operational application purposes","volume":"2","author":"Kutiev","year":"2012","journal-title":"J. Space Weather Space Clim."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"A20","DOI":"10.1051\/swsc\/2012020","article-title":"Upgrades to the topside sounders model assisted by Digisonde (TaD) and its validation at the topside ionosphere","volume":"2","author":"Belehaki","year":"2012","journal-title":"J. Space Weather Space Clim."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"RS4006","DOI":"10.1029\/2005RS003367","article-title":"A study of the shape of the topside electron density profile derived from incoherent scatter radar measurements over Arecibo and Millstone Hill","volume":"41","author":"Luan","year":"2006","journal-title":"Radio Sci."},{"key":"ref_62","first-page":"A10304","article-title":"Topside ionospheric scale heights retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation measurements","volume":"113","author":"Liu","year":"2008","journal-title":"J. Geophys. Res."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"2080","DOI":"10.1016\/j.asr.2015.08.008","article-title":"A new topside profiler based on Alouette\/ISIS topside sounding","volume":"56","author":"Zhu","year":"2015","journal-title":"Adv. Space Res."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"731","DOI":"10.1016\/j.asr.2006.05.032","article-title":"Modeling the F2 topside and plasmasphere for IRI using IMAGE\/RPI and ISIS data","volume":"39","author":"Reinisch","year":"2007","journal-title":"Adv. Space Res."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"937","DOI":"10.1016\/j.asr.2005.09.015","article-title":"Topside electron density in IRI and NeQuick: Features and limitations","volume":"37","author":"Radicella","year":"2006","journal-title":"Adv. Space Res."},{"key":"ref_66","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_67","doi-asserted-by":"crossref","first-page":"1929","DOI":"10.1126\/science.1121868","article-title":"Radar sounding of ionosphere of Mars","volume":"310","author":"Gurnett","year":"2005","journal-title":"Science"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/14\/8\/1817\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:51:04Z","timestamp":1760136664000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/14\/8\/1817"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,4,9]]},"references-count":67,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2022,4]]}},"alternative-id":["rs14081817"],"URL":"https:\/\/doi.org\/10.3390\/rs14081817","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,4,9]]}}}