{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/17984"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/17984","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Sferic propagation in the cutoff region of the earth-ionosphere waveguide","abstract":"The waveguide cutoff phenomenon provides information about the height of a waveguide. This cutoff for the earth-ionosphere waveguide is illuminated by lightning sferics and is used to monitor the change in ionosphere height through the day-night boundary. The observed ionospheric heights are found to be dependent on the three kinds of source-receiver paths: daytime, nighttime and mixed. Accurate locations for individual events are obtained from the National Lightning Detection Network (NLDN) to enable the analysis. Tweek sferics, which asymptote towards the transverse resonance frequency of the waveguide, predominate in the night path giving the most precise information about ionospheric heights. Weak dispersion and steep transitions in one-dimensional spectra provide information about daytime heights. Propagation over mixed paths reveals both daytime and nighttime signatures. Nighttime observations are also compared against theoretical predictions (Porrat et al, 2001). Agreement is best for large peak current events ( > 100) kA). Some indication of a residual daytime effect in a nighttime ionosphere is also observed.","abstract_html":"The waveguide cutoff phenomenon provides information about the height of a waveguide. This cutoff for the earth-ionosphere waveguide is illuminated by lightning sferics and is used to monitor the change in ionosphere height through the day-night boundary. The observed ionospheric heights are found to be dependent on the three kinds of source-receiver paths: daytime, nighttime and mixed. Accurate locations for individual events are obtained from the National Lightning Detection Network (NLDN) to enable the analysis. Tweek sferics, which asymptote towards the transverse resonance frequency of the waveguide, predominate in the night path giving the most precise information about ionospheric heights. Weak dispersion and steep transitions in one-dimensional spectra provide information about daytime heights. Propagation over mixed paths reveals both daytime and nighttime signatures. Nighttime observations are also compared against theoretical predictions (Porrat et al, 2001). Agreement is best for large peak current events ( > 100) kA). Some indication of a residual daytime effect in a nighttime ionosphere is also observed.","abstract_has_math":false,"creators":["Surana, Kunal K. (Kunal Krishna), 1979-"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.","school":null,"contributors":[],"advisors":["Earle Williams."],"committee_chairs":[],"committee_members":[],"year":2004,"date_issued":"2004","date_published":"2004","updated_at":"2026-07-22T22:22:16Z","subjects":["Electrical Engineering and Computer Science."],"languages":["eng"],"rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/17984","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Earle Williams."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science."]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science."]},{"key":"dc:creator","label":"Author","values":["Surana, Kunal K. (Kunal Krishna), 1979-"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2005-06-02T19:30:39Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2005-06-02T19:30:39Z"]},{"key":"dc:date.issued","label":"Date","values":["2004"]},{"key":"dc:publisher","label":"Institution","values":["Massachusetts Institute of Technology"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Electrical Engineering and Computer Science."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1721.1/17984"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.","Includes bibliographical references (leaves 93-96)."]},{"key":"dc:description.abstract","label":"Abstract","values":["The waveguide cutoff phenomenon provides information about the height of a waveguide. This cutoff for the earth-ionosphere waveguide is illuminated by lightning sferics and is used to monitor the change in ionosphere height through the day-night boundary. The observed ionospheric heights are found to be dependent on the three kinds of source-receiver paths: daytime, nighttime and mixed. Accurate locations for individual events are obtained from the National Lightning Detection Network (NLDN) to enable the analysis. Tweek sferics, which asymptote towards the transverse resonance frequency of the waveguide, predominate in the night path giving the most precise information about ionospheric heights. Weak dispersion and steep transitions in one-dimensional spectra provide information about daytime heights. Propagation over mixed paths reveals both daytime and nighttime signatures. Nighttime observations are also compared against theoretical predictions (Porrat et al, 2001). Agreement is best for large peak current events ( > 100) kA). Some indication of a residual daytime effect in a nighttime ionosphere is also observed."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.Eng.and S.B."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Sferic propagation in the cutoff region of the earth-ionosphere waveguide"]}]}],"canonical_facts":{"dc:contributor.advisor":["Earle Williams."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science."],"dc:contributor.other":["Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science."],"dc:creator":["Surana, Kunal K. (Kunal Krishna), 1979-"],"dc:date.accessioned":["2005-06-02T19:30:39Z"],"dc:date.available":["2005-06-02T19:30:39Z"],"dc:date.issued":["2004"],"dc:description":["Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.","Includes bibliographical references (leaves 93-96)."],"dc:description.abstract":["The waveguide cutoff phenomenon provides information about the height of a waveguide. This cutoff for the earth-ionosphere waveguide is illuminated by lightning sferics and is used to monitor the change in ionosphere height through the day-night boundary. The observed ionospheric heights are found to be dependent on the three kinds of source-receiver paths: daytime, nighttime and mixed. Accurate locations for individual events are obtained from the National Lightning Detection Network (NLDN) to enable the analysis. Tweek sferics, which asymptote towards the transverse resonance frequency of the waveguide, predominate in the night path giving the most precise information about ionospheric heights. Weak dispersion and steep transitions in one-dimensional spectra provide information about daytime heights. Propagation over mixed paths reveals both daytime and nighttime signatures. Nighttime observations are also compared against theoretical predictions (Porrat et al, 2001). Agreement is best for large peak current events ( > 100) kA). Some indication of a residual daytime effect in a nighttime ionosphere is also observed."],"dc:description.degree":["M.Eng.and S.B."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/1721.1/17984"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Electrical Engineering and Computer Science."],"dc:title":["Sferic propagation in the cutoff region of the earth-ionosphere waveguide"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:22:16Z"}