The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa

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dc.contributor.advisorHewitson, Bruceen_ZA
dc.contributor.advisorLandman, W Aen_ZA
dc.contributor.authorKruger, A Cen_ZA
dc.date.accessioned2014-11-21T16:09:12Z
dc.date.available2014-11-21T16:09:12Z
dc.date.issued1999en_ZA
dc.descriptionBibliography: leaves 93-101.en_ZA
dc.description.abstractRelationships between the El Niño-Southern Oscillation phenomenon (ENSO), seasonal rainfall, and atmospheric circulation patterns at the 1000 hPa and 500 hPa levels are investigated. Firstly, correlations between early-summer (October to December), late-summer (January to March) rainfall over South Africa, and sea-surface temperatures in the NINO3 region in the equatorial Pacific Ocean were investigated, where the correlations in the case for late-summer showed much better spatial coherence than in the case for early-summer. Consequently, the study further concentrated only on late summer. The influence of the quasi 18-20 year oscillation of summer rainfall on the effect of El Niño and La Niña events was also investigated, and it was found that during an epoch of above-normal/below-normal rainfall a moderating effect is evident on the severity of El Niño/La Niña events so that on average even above-normal/below-normal rainfall is experienced during such events. Canonical correlation analysis (CCA) was applied to different combinations of years, to find associations between equatorial Pacific sea-surface temperatures and deviations in circulation patterns during certain years. Some at the above results were then verified by model runs, to further prove the relationships not to be coincidental, and to add more degrees of freedom. The results of CCA were then separately interpreted for each combination of seasons (e. g. El Niño during the above-normal phase at the 500 hPa level) with the aid of average circulation maps for different combinations of years. Above - or below-normal rainfall during such years could then be explained in terms of deviations of general synoptic features at the surface and 500 hPa levels.en_ZA
dc.identifier.apacitationKruger, A. C. (1999). <i>The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science. Retrieved from http://hdl.handle.net/11427/9764en_ZA
dc.identifier.chicagocitationKruger, A C. <i>"The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1999. http://hdl.handle.net/11427/9764en_ZA
dc.identifier.citationKruger, A. 1999. The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Kruger, A C AB - Relationships between the El Niño-Southern Oscillation phenomenon (ENSO), seasonal rainfall, and atmospheric circulation patterns at the 1000 hPa and 500 hPa levels are investigated. Firstly, correlations between early-summer (October to December), late-summer (January to March) rainfall over South Africa, and sea-surface temperatures in the NINO3 region in the equatorial Pacific Ocean were investigated, where the correlations in the case for late-summer showed much better spatial coherence than in the case for early-summer. Consequently, the study further concentrated only on late summer. The influence of the quasi 18-20 year oscillation of summer rainfall on the effect of El Niño and La Niña events was also investigated, and it was found that during an epoch of above-normal/below-normal rainfall a moderating effect is evident on the severity of El Niño/La Niña events so that on average even above-normal/below-normal rainfall is experienced during such events. Canonical correlation analysis (CCA) was applied to different combinations of years, to find associations between equatorial Pacific sea-surface temperatures and deviations in circulation patterns during certain years. Some at the above results were then verified by model runs, to further prove the relationships not to be coincidental, and to add more degrees of freedom. The results of CCA were then separately interpreted for each combination of seasons (e. g. El Niño during the above-normal phase at the 500 hPa level) with the aid of average circulation maps for different combinations of years. Above - or below-normal rainfall during such years could then be explained in terms of deviations of general synoptic features at the surface and 500 hPa levels. DA - 1999 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1999 T1 - The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa TI - The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa UR - http://hdl.handle.net/11427/9764 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9764
dc.identifier.vancouvercitationKruger AC. The relationship between ENSO, seasonal rainfall, and circulation patterns in South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1999 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9764en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Environmental and Geographical Scienceen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherAtmospheric Sciencesen_ZA
dc.titleThe relationship between ENSO, seasonal rainfall, and circulation patterns in South Africaen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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