An investigation into dry and wet spell characteristics over Zambia and into the onset of the rainy season

 

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dc.contributor.advisor Reason, Chris en_ZA
dc.contributor.author Hachigonta, Sepo Promise en_ZA
dc.date.accessioned 2014-07-31T08:04:49Z
dc.date.available 2014-07-31T08:04:49Z
dc.date.issued 2005 en_ZA
dc.identifier.citation Hachigonta, S. 2005. An investigation into dry and wet spell characteristics over Zambia and into the onset of the rainy season. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/4857
dc.description Includes bibliographical references (leaves 113-124).
dc.description.abstract Recurring dry/wet spells and decreased agricultural productivity during the last decade in the southern and northern parts of Zambia point to the need for a clearer understanding of these events, their frequencies and their possible connection to large-scale climate modes. Apart from having a high number of dry spells during the December-February (DJF) core rainy season, the southern part of Zambia is frequently subjected to late onset dates and short durations of the rainy season whereas the northern and northwestern region frequently have high numbers of wet spells which in most cases lead to flooding. Using CMAP and station data, rainfall variability in terms of dry spells, wet spells, onset and cessation dates of the Zambian rainy season and the associated circulation anomalies are investigated. The study also looks at relationship between these extreme events with Nin03.4 SST anomalies. Low level easterly anomalies over Zambia are enhanced during seasons with high dry spells. As a result, there is reduced moisture penetration into Zambia from the Angola low and reduced low level moisture convergence over the country and hence increased dry spells. During the seasons with high numbers of wet spells, there are low level westerly anomalies over southern Angola and western Zambia implying a strong moisture influx from the tropical South East Atlantic and increased convergence over Zambia. It was shown that El Nino (La Nina) events typically result in above (below) average DJF dry spell frequency in Zambia. Early onset dates over the northern parts of Zambia were observed to occur during strong El Nino seasons and the strength of the observed relationship with Nin03.4 SSTs seems to be stronger for years during the 1980s than those during the 1990s. Early onset dates tend to occur for years with higher than average dry spell frequency in the following DJF season. This suggests that early onset may be a disadvantage in that it often leads to more dry spells during the subsequent peak growing period of the season. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Environmental and Geographical Science en_ZA
dc.title An investigation into dry and wet spell characteristics over Zambia and into the onset of the rainy season en_ZA
dc.type Thesis / Dissertation en_ZA
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 Environmental and Geographical Science en_ZA
dc.type.qualificationlevel Masters en_ZA
dc.type.qualificationname MSc en_ZA
uct.type.filetype Text
uct.type.filetype Image


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