One-dimensional wave spectrum analysis of wind waves off Cape Town

 

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dc.contributor.advisor Harris, T F W en_ZA
dc.contributor.author Van Ieperen, Maarten Pieter en_ZA
dc.date.accessioned 2016-03-21T19:26:15Z
dc.date.available 2016-03-21T19:26:15Z
dc.date.issued 1970 en_ZA
dc.identifier.citation Van Ieperen, M. 1970. One-dimensional wave spectrum analysis of wind waves off Cape Town. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/18125
dc.description.abstract Wind waves in the vicinity of Cape Town, South Africa, were measured by means of an N.I.O. (England) ship-borne wave recorder, in water depths varying from 12 - 140 metres. One dimensional frequency spectra were computed from the records, by power spectrum analysis, based on the method of Blackman and Tukey, using an I.B.M. 1130 Computer. Assumptions of normality and stationarity were tested. The Gaussian assumption of the waves was found to be acceptable for the waters off Cape Town. At the 5% critical level, using the chi-square test, 3 out of 23 records tested were found to be non-Gaussian. No significant difference between the Gaussian properties of the deep and the shallow stations was found. Tests for stationarity applied to 3 selected records showed 1 record as clearly non-stationary. However, this recording was obtained under fluctuating wind conditions. Comparison of the total variances of the power spectra obtained in shoaling water showed a systematic decrease of variance with depth. Normalised spectra did not show a systematic selective attenuation of the variances with frequency. Factors which might have caused the systematic reduction of the total variances with depth have been examined. The bottom friction factor for this coast was estimated. The mean value of the bottom friction is 0.22. This is higher than found by other workers. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Oceanography en_ZA
dc.title One-dimensional wave spectrum analysis of wind waves off Cape Town en_ZA
dc.type Master Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Oceanography en_ZA
dc.type.qualificationlevel Masters
dc.type.qualificationname MSc en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Van Ieperen, M. P. (1970). <i>One-dimensional wave spectrum analysis of wind waves off Cape Town</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Oceanography. Retrieved from http://hdl.handle.net/11427/18125 en_ZA
dc.identifier.chicagocitation Van Ieperen, Maarten Pieter. <i>"One-dimensional wave spectrum analysis of wind waves off Cape Town."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Oceanography, 1970. http://hdl.handle.net/11427/18125 en_ZA
dc.identifier.vancouvercitation Van Ieperen MP. One-dimensional wave spectrum analysis of wind waves off Cape Town. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Oceanography, 1970 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18125 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Van Ieperen, Maarten Pieter AB - Wind waves in the vicinity of Cape Town, South Africa, were measured by means of an N.I.O. (England) ship-borne wave recorder, in water depths varying from 12 - 140 metres. One dimensional frequency spectra were computed from the records, by power spectrum analysis, based on the method of Blackman and Tukey, using an I.B.M. 1130 Computer. Assumptions of normality and stationarity were tested. The Gaussian assumption of the waves was found to be acceptable for the waters off Cape Town. At the 5% critical level, using the chi-square test, 3 out of 23 records tested were found to be non-Gaussian. No significant difference between the Gaussian properties of the deep and the shallow stations was found. Tests for stationarity applied to 3 selected records showed 1 record as clearly non-stationary. However, this recording was obtained under fluctuating wind conditions. Comparison of the total variances of the power spectra obtained in shoaling water showed a systematic decrease of variance with depth. Normalised spectra did not show a systematic selective attenuation of the variances with frequency. Factors which might have caused the systematic reduction of the total variances with depth have been examined. The bottom friction factor for this coast was estimated. The mean value of the bottom friction is 0.22. This is higher than found by other workers. DA - 1970 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1970 T1 - One-dimensional wave spectrum analysis of wind waves off Cape Town TI - One-dimensional wave spectrum analysis of wind waves off Cape Town UR - http://hdl.handle.net/11427/18125 ER - en_ZA


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