Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

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This M. Sc. thesis studies the statistical characteristics of convective storms in a monsoon regime in Darwin, northern Australia. It has been conducted with the use of radar. Enhanced knowledge of tropical convection is essential in studies of the global climate, and this study aims to bring light on some special characteristics of storms in a tropical environment. The observed behaviour of convective storms can be implemented in the parameterisation of these in cloud-resolving regional and global models. The wet season was subdivided into three regimes; build-up and breaks, the monsoon and the dry monsoon. Using a cell tracking system called TITAN, these regimes were shown to support different storm characteristics in terms of their temporal, spatial and height distributions. The build-up and break storms were seen to be more vigorous and particularly modulated diurnally by sea breezes. The monsoon was dominated by frequent but less intense and vertically less extensive convective cores. The explanation for this could be found in the atmospheric environment, with monsoonal convection having oceanic origins together with a mean upward motion of air through the depth of the troposphere. The dry monsoon was characterised by suppressed convection due to the presence of dry mid-level air. The effects of wind shear on convective line orientations were examined. The results show a diurnal evolution from low-level shear parallel orientations of convective lines to low-level shear perpendicular during build-up and breaks. The monsoon was dominated by complex orientations of convective lines. The thesis includes a study of merged and splitted cells, which have been separated from other storms, and mergers were shown to support more vigorous convection in terms of height distribution and reflectivity profiles. They were also seen to be the most long-lived category of storms as well as the most common type. Split storms were generally weaker, indicative of their general tendency to decay shortly after the split occurred. / En statistisk studie av konvektiva celler i en miljö som präglas av monsunförhållanden har utförts i Darwin, norra Australien, med hjälp av radar. En ökad förståelse for tropisk konvektion är nödvändig for att kunna studera klimatet globalt. Denna studie har bidragit till denna kunskapsbas genom att studera några viktiga parametrar hos konvektiva celler i en tropisk miljö. De observerade egenskaperna hos dessa celler kan implementeras i parametriseringen av högupplösta regionala och globala modeller. Regnperioden delades upp i tre olika regimer; uppbyggnad och avbrott, monsun och torr monsun. Genom att använda ett cellsökande system kallat TITAN, visade sig dessa regimer uppvisa olika karakteristika vad gäller tids- och rumsmässig samt vertikal distribution av konvektionsceller. Uppbyggnad- och avbrottsregimen dominerades av mäktiga och intensiva konvektionsceller, och modulerades av sjöbrisar på en daglig basis. Monsunen dominerades av talrika men mindre intensiva celler. Anledningen till detta kan finnas i atmosfäriska förhållanden, dar monsunen dominerades av konvektionsceller med oceanisk härkomst och allmän hävning genom större delen av troposfären. Den torra monsunen präglades av försvagad konvektion på grund av närvaron av mycket torr luft på medelhöga nivåer. Effekten av vindskjuvning på orienteringen av bylinjer undersöktes. Resultaten visar att en daglig övergång från en orientering som var parallell med vindskjuvningsvektorn till en vinkelrät orientering dominerade under uppbyggnad och avbrott. Monsunen präglades av komplexa orienteringar av bylinjer. Sammanväxande och splittrande celler separerades fran andra celler och undersöktes speciellt. De sammanväxande cellerna uppvisade mer intensiv konvektion och större vertikal maktighet. Denna kategori av celler, som var den vanligaste typen av ickeisolerade celler, levde också längre än andra celltyper. Splittrande celler var generellt svagare än andra celler, vilket indikerade den generella tendensen för denna celltyp att brytas ner strax efter det att en splittring ägt rum.

A significant minority of at risk residents in the USA do not evacuate from an approaching hurricane when they are advised to by local authorities. This causes unnecessary deaths, injuries and suffering; a situation which is likely to intensify under predicted climate change. This thesis argues that non-evacuation is not fully understood as both the academic and policy framing of the decision to evacuate is centred around technical and socio-economic approaches which assume that risk is objective and “rational” people will evacuate if they have the material means to do so. This thesis argues that rationalities are differentiated and decision making is also a process which is influenced by members of a social network. Therefore there is a need for a more constructivist approach to get a deeper understanding of the subjectivity of hurricane evacuation. In this thesis, the theory of reasoned action is used as the framework of decision making as it highlights the importance of subjective attitudes and subjective norms on behaviour. A mixed methods case study of Hurricane Ike is used to analyse the evacuation of Galveston Island, Texas. Firstly a “Q” study was undertaken with 40 residents of Galveston, which unveiled four distinct subjective evacuation attitudes, demonstrating that people understand hurricane risk in different ways which impact on their decision to evacuate. The results of the Q study were then used to parameterise an agent based model, designed to investigate community level evacuation. The model showed that it is possible to explain island-level evacuation through the combination of subjective evacuation attitudes and subjective norms which can interact to produce emergent, or unpredicted behaviour. This thesis represents a fundamental challenge to positivist approaches and clearly demonstrates the value of a more constructivist approach to understanding hurricane evacuation based on subjective evacuation attitudes and subjective norms.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Este trabajo presenta un marco metodológico para la estimación de la vulnerabilidad costera al impacto de tormentas a dos escalas, regional y local. Se hace una evaluación de la vulnerabilidad costera física mediante la cuantificación de dos componentes: erosión e inundación. Posteriormente, ambos elementos son integrados en un Índice de Vulnerabilidad Costera. La metodología desarrollada cubre los siguientes pasos: (i) clasificación de tormentas, (ii) evaluación de la respuesta inducida en la playa -inundación y erosión- (iii) caracterización de las playas en la zona de estudio (iv) definición del índice de vulnerabilidad costera y (v) evaluación de la vulnerabilidad costera. Estos pasos han sido derivados y aplicados a la costa catalana (Mediterráneo Noroccidental español) y pueden ser adaptados a otras costas. Los resultados obtenidos pueden ser fácilmente utilizados por los gestores costeros para identificar zonas costeras sensibles a una clase de tormenta dada y sus procesos inducidos (inundación, erosión o la combinación de ambos) para decidir donde tomar acciones para mitigar estos impactos. / This work presents a methodological framework for the estimation of coastal vulnerability to storm impacts at two scales, regional and local. It estimates the physical coastal vulnerability through the quantification of two components: erosion and flooding. Afterwards the two elements are integrated into the so called Coastal Vulnerability Index. The methodological process covers the following steps: (i) storm classification, (ii) evaluation of the induced beach response -flood and erosion-, (iii) coastal zone characterization, (iv) definition of a coastal vulnerability index to storms and (v) assessment of the coastal vulnerability. These steps have been derived and applied to the Catalan coast (NW Spanish Mediterranean) and can be adapted to other coasts. The obtained results can be used by coastal managers in an easy manner to identify sensitive coastal stretches for a given storm class and the induced processes (flooding, erosion or combination of both) with the purpose to take actions and mitigate these impacts.

This thesis aims to examine how Native Americans survive through storytelling, using Linda Hogan¡¦s Solar Storms as my anchor text. The entire work proceeds in five chapters. The first chapter is my introduction. Chapter Two, ¡§Famine Stories,¡¨ delineates the mental starvation that Native Americans suffer. In this novel, there are abundant stories dealing with the trauma caused by colonial deprivation. Such stories are termed as ¡§famine stories,¡¨ which according to its influential level, is further divided into three kinds¡Xpersonal famine stories, familial famine stories, and communal famine stories. These stories intertwine with one another, and their causes can all be traced to the colonial history. Chapter Two, ¡§Feed Me Stories,¡¨ intends to seek a recovery from Native people¡¦s mental famine. Taking Angel¡¦s self-constructing journey as an example, I argue that storytelling reconnects the lost Native American with the lost past. In addition, stories reconstruct the Native worldview, which looks forward to harmony and balance between the human and non-human. Emerged in her grandmothers¡¦ storytelling, Angel comes to realize her mother culture and rebuild her Native identity. Moreover, she retrieves her correlation with the land, develops an intimacy with animals and plants and inherits her family tradition to be an herbal woman. She at last recovers from her psychical wounds. Chapter Three, ¡§The Future Storyteller,¡¨ sheds light on Hogan¡¦s intention to carry Native survivance into the future. Protesting against dam construction, Angel takes the tribal future as her responsibility. She devotes her love to nurturing the tribal youth and justifying her Native living right by revealing the deprivation which traumatizes the Native community. Her telling is powerful. It challenges the dominators¡¦ covering the truth up, and puts Native perspective into attention. She de-annihilates Native culture and assures its prosperity in the future. What she does corresponds to Gerald Vizenor¡¦s ¡§Native Survivance,¡¨ ensuring ¡§an active sense of presence,¡¨ and ¡§the continuance of native stories¡¨ (vii). The entire tribe is reunified due to storyteller¡¦s effort and the community is again ¡§the Beautiful People¡¨ (313).

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