Antipodal receptions in global acoustics

dc.contributor.advisorBrundrit, Geoffen_ZA
dc.contributor.authorCourtney, Jennifer Susanen_ZA
dc.date.accessioned2014-11-10T09:09:19Z
dc.date.available2014-11-10T09:09:19Z
dc.date.issued1997en_ZA
dc.descriptionBibliography: leaves 96-97.en_ZA
dc.description.abstractGlobal Acoustic Propagation is a recently developed scientific discipline within the study of long range underwater acoustic propagation. Acoustic propagation over extremely long ranges involves a combination of effects from earth curvature and the global distribution of oceanographic and geophysical features. Antipodal receptions, that is to ranges of the order of 20Mm (1 Megameter = 1 000 km), require underwater acoustic propagation to very long ranges and thus effects due to the form of the earth and the range dependence of the sound speed field within the ocean can not be ignored. The purpose of this thesis is to investigate the nature of antipodal receptions with reference to the form of the earth and horizontal sound speed variations within the ocean and thereby contribute to the new and specialized field of study, Global Acoustic Propagation. Close to an acoustic source acoustic energy diverges so that local signal strengths decrease with distance from the source. However, as the antipodal region is approached acoustic energy that has not been blocked by bathymetric features will refocus, counteracting the distance loss rule. Thus at antipodal sites there is a good prospect of receiving a focused signal. Even so, the ellipsoidal form of the earth and the horizontal variability within the sound speed field of the ocean means that the re-focusing will result in a region of enhanced signal rather than an exact antipodal point. The precise detail of the advantage of placing receivers in the antipodal region will depend upon the paths taken by the acoustic energy and the characteristics of the acoustic medium encountered along each path. The proposal for this thesis is to develop an algorithm to determine the nature of the antipodal region under certain physical assumptions. The physical assumptions are referred to as the geometric assumption, which refers to the form of the earth, and the refractive assumption, which refers to the horizontal variability of sound speed within the world oceans.en_ZA
dc.identifier.apacitationCourtney, J. S. (1997). <i>Antipodal receptions in global acoustics</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Oceanography. Retrieved from http://hdl.handle.net/11427/9517en_ZA
dc.identifier.chicagocitationCourtney, Jennifer Susan. <i>"Antipodal receptions in global acoustics."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Oceanography, 1997. http://hdl.handle.net/11427/9517en_ZA
dc.identifier.citationCourtney, J. 1997. Antipodal receptions in global acoustics. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Courtney, Jennifer Susan AB - Global Acoustic Propagation is a recently developed scientific discipline within the study of long range underwater acoustic propagation. Acoustic propagation over extremely long ranges involves a combination of effects from earth curvature and the global distribution of oceanographic and geophysical features. Antipodal receptions, that is to ranges of the order of 20Mm (1 Megameter = 1 000 km), require underwater acoustic propagation to very long ranges and thus effects due to the form of the earth and the range dependence of the sound speed field within the ocean can not be ignored. The purpose of this thesis is to investigate the nature of antipodal receptions with reference to the form of the earth and horizontal sound speed variations within the ocean and thereby contribute to the new and specialized field of study, Global Acoustic Propagation. Close to an acoustic source acoustic energy diverges so that local signal strengths decrease with distance from the source. However, as the antipodal region is approached acoustic energy that has not been blocked by bathymetric features will refocus, counteracting the distance loss rule. Thus at antipodal sites there is a good prospect of receiving a focused signal. Even so, the ellipsoidal form of the earth and the horizontal variability within the sound speed field of the ocean means that the re-focusing will result in a region of enhanced signal rather than an exact antipodal point. The precise detail of the advantage of placing receivers in the antipodal region will depend upon the paths taken by the acoustic energy and the characteristics of the acoustic medium encountered along each path. The proposal for this thesis is to develop an algorithm to determine the nature of the antipodal region under certain physical assumptions. The physical assumptions are referred to as the geometric assumption, which refers to the form of the earth, and the refractive assumption, which refers to the horizontal variability of sound speed within the world oceans. DA - 1997 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1997 T1 - Antipodal receptions in global acoustics TI - Antipodal receptions in global acoustics UR - http://hdl.handle.net/11427/9517 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9517
dc.identifier.vancouvercitationCourtney JS. Antipodal receptions in global acoustics. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Oceanography, 1997 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9517en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Oceanographyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherOceanographyen_ZA
dc.titleAntipodal receptions in global acousticsen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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