{"id":"https://openalex.org/W2998366958","doi":"https://doi.org/10.1109/tgrs.2019.2957716","title":"Assimilating VLF Transmitter Observations With an LETKF for Spatial Estimates of the ${D}$ -Region Ionosphere","display_name":"Assimilating VLF Transmitter Observations With an LETKF for Spatial Estimates of the ${D}$ -Region Ionosphere","publication_year":2019,"publication_date":"2019-12-24","ids":{"openalex":"https://openalex.org/W2998366958","doi":"https://doi.org/10.1109/tgrs.2019.2957716","mag":"2998366958"},"language":"en","primary_location":{"id":"doi:10.1109/tgrs.2019.2957716","is_oa":false,"landing_page_url":"https://doi.org/10.1109/tgrs.2019.2957716","pdf_url":null,"source":{"id":"https://openalex.org/S111326731","display_name":"IEEE Transactions on Geoscience and Remote Sensing","issn_l":"0196-2892","issn":["0196-2892","1558-0644"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310319808","host_organization_name":"Institute of Electrical and Electronics Engineers","host_organization_lineage":["https://openalex.org/P4310319808"],"host_organization_lineage_names":["Institute of Electrical and Electronics Engineers"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"IEEE Transactions on Geoscience and Remote Sensing","raw_type":"journal-article"},"type":"article","indexed_in":["crossref"],"open_access":{"is_oa":false,"oa_status":"closed","oa_url":null,"any_repository_has_fulltext":false},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5017466765","display_name":"Forrest Gasdia","orcid":"https://orcid.org/0000-0002-0003-3975"},"institutions":[{"id":"https://openalex.org/I188538660","display_name":"University of Colorado Boulder","ror":"https://ror.org/02ttsq026","country_code":"US","type":"education","lineage":["https://openalex.org/I188538660"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"Forrest Gasdia","raw_affiliation_strings":["Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, USA"],"raw_orcid":"https://orcid.org/0000-0002-0003-3975","affiliations":[{"raw_affiliation_string":"Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, USA","institution_ids":["https://openalex.org/I188538660"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5025956625","display_name":"Robert A. Marshall","orcid":"https://orcid.org/0000-0003-0974-1609"},"institutions":[{"id":"https://openalex.org/I188538660","display_name":"University of Colorado Boulder","ror":"https://ror.org/02ttsq026","country_code":"US","type":"education","lineage":["https://openalex.org/I188538660"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"Robert A. Marshall","raw_affiliation_strings":["Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, USA"],"raw_orcid":"https://orcid.org/0000-0003-0974-1609","affiliations":[{"raw_affiliation_string":"Department of Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, USA","institution_ids":["https://openalex.org/I188538660"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":2,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":0.47,"has_fulltext":false,"cited_by_count":12,"citation_normalized_percentile":{"value":0.71241046,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":89,"max":99},"biblio":{"volume":"58","issue":"5","first_page":"3526","last_page":"3543"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10159","display_name":"Ionosphere and magnetosphere dynamics","score":0.9998999834060669,"subfield":{"id":"https://openalex.org/subfields/3103","display_name":"Astronomy and Astrophysics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T10159","display_name":"Ionosphere and magnetosphere dynamics","score":0.9998999834060669,"subfield":{"id":"https://openalex.org/subfields/3103","display_name":"Astronomy and Astrophysics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10655","display_name":"GNSS positioning and interference","score":0.9990000128746033,"subfield":{"id":"https://openalex.org/subfields/2202","display_name":"Aerospace Engineering"},"field":{"id":"https://openalex.org/fields/22","display_name":"Engineering"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10466","display_name":"Meteorological Phenomena and Simulations","score":0.9977999925613403,"subfield":{"id":"https://openalex.org/subfields/1902","display_name":"Atmospheric Science"},"field":{"id":"https://openalex.org/fields/19","display_name":"Earth and Planetary Sciences"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/ionosphere","display_name":"Ionosphere","score":0.8580310940742493},{"id":"https://openalex.org/keywords/remote-sensing","display_name":"Remote sensing","score":0.5371208190917969},{"id":"https://openalex.org/keywords/transmitter","display_name":"Transmitter","score":0.532750129699707},{"id":"https://openalex.org/keywords/data-assimilation","display_name":"Data assimilation","score":0.44008195400238037},{"id":"https://openalex.org/keywords/plasmasphere","display_name":"Plasmasphere","score":0.42808419466018677},{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.35299354791641235},{"id":"https://openalex.org/keywords/geology","display_name":"Geology","score":0.31591978669166565},{"id":"https://openalex.org/keywords/geophysics","display_name":"Geophysics","score":0.31097549200057983},{"id":"https://openalex.org/keywords/meteorology","display_name":"Meteorology","score":0.27018940448760986},{"id":"https://openalex.org/keywords/physics","display_name":"Physics","score":0.25134289264678955},{"id":"https://openalex.org/keywords/telecommunications","display_name":"Telecommunications","score":0.16935527324676514},{"id":"https://openalex.org/keywords/magnetosphere","display_name":"Magnetosphere","score":0.1253625750541687},{"id":"https://openalex.org/keywords/plasma","display_name":"Plasma","score":0.12506842613220215}],"concepts":[{"id":"https://openalex.org/C116403925","wikidata":"https://www.wikidata.org/wiki/Q162219","display_name":"Ionosphere","level":2,"score":0.8580310940742493},{"id":"https://openalex.org/C62649853","wikidata":"https://www.wikidata.org/wiki/Q199687","display_name":"Remote sensing","level":1,"score":0.5371208190917969},{"id":"https://openalex.org/C47798520","wikidata":"https://www.wikidata.org/wiki/Q190157","display_name":"Transmitter","level":3,"score":0.532750129699707},{"id":"https://openalex.org/C24552861","wikidata":"https://www.wikidata.org/wiki/Q2670177","display_name":"Data assimilation","level":2,"score":0.44008195400238037},{"id":"https://openalex.org/C118691173","wikidata":"https://www.wikidata.org/wiki/Q1546045","display_name":"Plasmasphere","level":4,"score":0.42808419466018677},{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.35299354791641235},{"id":"https://openalex.org/C127313418","wikidata":"https://www.wikidata.org/wiki/Q1069","display_name":"Geology","level":0,"score":0.31591978669166565},{"id":"https://openalex.org/C8058405","wikidata":"https://www.wikidata.org/wiki/Q46255","display_name":"Geophysics","level":1,"score":0.31097549200057983},{"id":"https://openalex.org/C153294291","wikidata":"https://www.wikidata.org/wiki/Q25261","display_name":"Meteorology","level":1,"score":0.27018940448760986},{"id":"https://openalex.org/C121332964","wikidata":"https://www.wikidata.org/wiki/Q413","display_name":"Physics","level":0,"score":0.25134289264678955},{"id":"https://openalex.org/C76155785","wikidata":"https://www.wikidata.org/wiki/Q418","display_name":"Telecommunications","level":1,"score":0.16935527324676514},{"id":"https://openalex.org/C130443932","wikidata":"https://www.wikidata.org/wiki/Q6915","display_name":"Magnetosphere","level":3,"score":0.1253625750541687},{"id":"https://openalex.org/C82706917","wikidata":"https://www.wikidata.org/wiki/Q10251","display_name":"Plasma","level":2,"score":0.12506842613220215},{"id":"https://openalex.org/C127162648","wikidata":"https://www.wikidata.org/wiki/Q16858953","display_name":"Channel (broadcasting)","level":2,"score":0.0},{"id":"https://openalex.org/C62520636","wikidata":"https://www.wikidata.org/wiki/Q944","display_name":"Quantum mechanics","level":1,"score":0.0}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.1109/tgrs.2019.2957716","is_oa":false,"landing_page_url":"https://doi.org/10.1109/tgrs.2019.2957716","pdf_url":null,"source":{"id":"https://openalex.org/S111326731","display_name":"IEEE Transactions on Geoscience and Remote Sensing","issn_l":"0196-2892","issn":["0196-2892","1558-0644"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310319808","host_organization_name":"Institute of Electrical and Electronics Engineers","host_organization_lineage":["https://openalex.org/P4310319808"],"host_organization_lineage_names":["Institute of Electrical and Electronics Engineers"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"IEEE Transactions on Geoscience and Remote Sensing","raw_type":"journal-article"}],"best_oa_location":null,"sustainable_development_goals":[{"score":0.4099999964237213,"id":"https://metadata.un.org/sdg/14","display_name":"Life below water"}],"awards":[],"funders":[{"id":"https://openalex.org/F4320333566","display_name":"National Defense Science and Engineering Graduate","ror":null}],"has_content":{"pdf":false,"grobid_xml":false},"content_urls":null,"referenced_works_count":71,"referenced_works":["https://openalex.org/W74549230","https://openalex.org/W109932990","https://openalex.org/W179446825","https://openalex.org/W1496039999","https://openalex.org/W1529105200","https://openalex.org/W1580654971","https://openalex.org/W1640593231","https://openalex.org/W1644896510","https://openalex.org/W1666199919","https://openalex.org/W1668064416","https://openalex.org/W1976487265","https://openalex.org/W1987308763","https://openalex.org/W1993123242","https://openalex.org/W2000944407","https://openalex.org/W2005521960","https://openalex.org/W2019436049","https://openalex.org/W2030664127","https://openalex.org/W2030774493","https://openalex.org/W2036640959","https://openalex.org/W2038267864","https://openalex.org/W2041701766","https://openalex.org/W2044922933","https://openalex.org/W2045192354","https://openalex.org/W2045754316","https://openalex.org/W2048729261","https://openalex.org/W2058160370","https://openalex.org/W2059566110","https://openalex.org/W2068193552","https://openalex.org/W2073375954","https://openalex.org/W2088735342","https://openalex.org/W2090422660","https://openalex.org/W2092619507","https://openalex.org/W2096471740","https://openalex.org/W2103018097","https://openalex.org/W2105394622","https://openalex.org/W2105934661","https://openalex.org/W2111965804","https://openalex.org/W2123211102","https://openalex.org/W2147119488","https://openalex.org/W2147175366","https://openalex.org/W2147423475","https://openalex.org/W2149612118","https://openalex.org/W2154145290","https://openalex.org/W2160444846","https://openalex.org/W2161358768","https://openalex.org/W2170281913","https://openalex.org/W2173190456","https://openalex.org/W2176150232","https://openalex.org/W2179860363","https://openalex.org/W2204436720","https://openalex.org/W2342566926","https://openalex.org/W2469805270","https://openalex.org/W2489898035","https://openalex.org/W2761741927","https://openalex.org/W2783928379","https://openalex.org/W2790456167","https://openalex.org/W2793285761","https://openalex.org/W2883676711","https://openalex.org/W2890004328","https://openalex.org/W2893822433","https://openalex.org/W2903512467","https://openalex.org/W2951980816","https://openalex.org/W3015516728","https://openalex.org/W3021452227","https://openalex.org/W3137812461","https://openalex.org/W4255777770","https://openalex.org/W4285719527","https://openalex.org/W4388322023","https://openalex.org/W6637242489","https://openalex.org/W6775392761","https://openalex.org/W6776727053"],"related_works":["https://openalex.org/W1975852068","https://openalex.org/W2107107828","https://openalex.org/W3211535430","https://openalex.org/W2044949058","https://openalex.org/W2992597706","https://openalex.org/W2094016761","https://openalex.org/W657208614","https://openalex.org/W2009576785","https://openalex.org/W2087636852","https://openalex.org/W2155209365"],"abstract_inverted_index":{"The":[0,144,226],"D-region":[1,77,97,141],"ionosphere":[2],"plays":[3],"an":[4,89,107],"important":[5],"role":[6],"in":[7,235,247],"coupling":[8],"the":[9,33,43,64,76,86,102,130,140,157,161,175,181,189,209,212,223,236,242,248],"neutral":[10],"atmosphere":[11],"to":[12,60,94,124,135,159,177,180,232],"denser":[13],"ionospheric":[14,68],"plasma":[15],"above.":[16],"Practically,":[17],"it":[18,57],"impacts":[19],"long-range":[20],"radio":[21,114,137],"communications":[22,29],"between":[23],"extremely":[24,51],"low":[25,52,111],"frequencies":[26,37],"(ELFs),":[27],"where":[28],"are":[30,40],"enabled":[31],"by":[32,42],"layer,":[34],"and":[35,50,72,116,139,174,191,197],"high":[36],"(HFs),":[38],"which":[39],"attenuated":[41],"layer.":[44],"A":[45],"combination":[46],"of":[47,63,75,88,109,129,163,166,211,244],"its":[48,133],"altitude":[49,127],"electron":[53,98],"density":[54,99],"means":[55],"that":[56,219],"is":[58,78,142,220],"difficult":[59],"make":[61],"measurements":[62,138],"region":[65],"using":[66,106,200],"typical":[67],"remote":[69],"sensing":[70],"techniques,":[71],"our":[73],"knowledge":[74],"limited":[79],"as":[80,183],"a":[81,206,217],"result.":[82],"This":[83],"article":[84],"presents":[85],"development":[87],"ensemble":[90],"Kalman":[91],"filter":[92,190,213],"method":[93,227],"spatially":[95],"map":[96],"profiles":[100],"over":[101],"continental":[103],"United":[104],"States":[105],"array":[108],"very":[110],"frequency":[112],"(VLF)":[113],"transmitters":[115],"receivers.":[117],"Data":[118],"assimilation":[119],"has":[120,146],"previously":[121],"been":[122],"used":[123],"estimate":[125,182],"higher":[126],"regions":[128],"ionosphere,":[131],"but":[132],"application":[134,231],"VLF":[136],"new.":[143],"technique":[145],"several":[147],"favorable":[148],"features,":[149],"including":[150],"statistical":[151],"confidence":[152],"measures":[153],"with":[154,216],"every":[155],"estimate,":[156],"ability":[158,176],"localize":[160],"influence":[162],"measurements,":[164],"inclusion":[165],"physically":[167],"realistic":[168],"spatial":[169],"correlations,":[170],"relatively":[171],"fast":[172],"convergence,":[173],"add":[178],"observations":[179],"they":[184],"become":[185],"available.":[186],"We":[187,203],"describe":[188],"present":[192,205],"results":[193],"for":[194,230,240],"day,":[195],"night,":[196],"terminator":[198],"ionospheres":[199],"simulated":[201],"data.":[202],"also":[204],"study":[207],"on":[208],"robustness":[210],"when":[214],"initialized":[215],"prior":[218],"far":[221],"from":[222],"true":[224],"ionosphere.":[225],"shows":[228],"promise":[229],"real":[233],"data":[234],"near":[237],"future,":[238],"especially":[239],"estimating":[241],"characteristics":[243],"large-scale":[245],"features":[246],"D-region.":[249]},"counts_by_year":[{"year":2025,"cited_by_count":7},{"year":2023,"cited_by_count":2},{"year":2022,"cited_by_count":2},{"year":2021,"cited_by_count":1}],"updated_date":"2026-06-11T09:08:48.828518","created_date":"2025-10-10T00:00:00"}
