This thesis presents hypothetical return plans for hurricane evacuees who have previously evacuated their residence in southern Rhode Island. Using Geographic Information Systems software, appropriate time tables for evacuees to return to their homes are generated. Two case scenarios based on Category 3 and 4 intensity hurricanes making landfall in Westerly, Rhode Island were simulated. Over the last century, population and especially home values in coastal Rhode Island have increased leaving great risk to those in the area. Statistically, hurricanes are less likely to strike Rhode Island than the Gulf Coast or the Southeastern United States. However, within the last century dangerous and damaging hurricanes have affected Rhode Island. This lower frequency of hurricanes decreases awareness and emphasizes the need for further research. Reentry zones for each scenario are defined and ranked by severity of damage using debris, building damage, potential economic loss and population displacements with HAZUS software. Results from both Category 3 and Category 4 test cases show that the downtown census tract experiences the greatest amount of damage and longest return times for evacuees. / Department of Geography

Previous numerical and theoretical results based on constant diapycnal diffusivity suggested the abyssal meridional overturning circulation (MOC) should weaken as winds over the Southern Ocean intensify. We corroborate this result in a simple ocean model, but find it does not hold in more complex models. First, models with a variable eddy transfer coefficient and simple yet dynamic atmosphere and sea-ice models show an increase, albeit slightly, of the abyssal MOC under increasing winds. Second, the abyssal MOC significantly strengthens with winds when diapycnal diffusivity is parameterized to be energetically supported by the winds. This tests the emerging idea that a significant fraction of the wind energy input to the large-scale ocean circulation is removed by mesoscale eddies and may then be transferred to internal lee waves, and thence to bottom-enhanced diapycnal mixing. A scaling theory of the abyssal MOC is extended to incorporate this energy pathway, corroborating our numerical results. / Graduate / 0415 / gstanley@uvic.ca

Peatlands in Southern South America (SSA), in the path of the Southern Westerly Wind belt (SWW), offer the potential of reliable palaeoclimate archives. This investigation aimed to test the late-Holocene climate signal related to variability of the SWW. Three sites were investigated: San Juan and Karukinka bog, southernmost Chile and San Carlos, a Sphagnum dominated bog, discovered in the Falkland Islands, to form a regional comparison. A multi-proxy approach was used, combining both palaeoecological and stable isotopic methods. At one site, Karukinka, intra-site replicability was tested across three profiles located along a microtopographical gradient. A low number of statistically significant correlations between proxies were evident. KAR-EM-1, the low-hummock profile, displayed the highest number of significant correlations, suggesting an optimal coring location. Chronological uncertainty in the high-hummock profile, KAR-EM-3, was the focus of discussion. Intra-site replicability between the palaeoecological records was improved by plotting the records against a ‘master chronology’, from the mid-hummock profile, KAR-EM-2, assuming a synchronous acrotelm-catotelm boundary across the profiles. The testate amoeba inferred depth to water table (WTD) reconstructions offered the highest intra-site coherence, while the stable isotope records suggested generally poor intra-site replicability. A semi-quantitative method of intra-site comparison was carried out which resulted in a number of climate scenarios. The inter-site comparison assessed correlations between the records from the three sites. A lack of significant correlations between the sites may have been due to regional climate variations and differences in the temporal resolution of the records. Robust climatic inferences were limited to the last 300 years. The WTD reconstructions displayed the highest inter-site coherence and suggested a drying trend after AD 1930 due to a southerly shift of the SWW. Late-Holocene climate variability was inferred from the palaeoecological records from Karukinka. Two periods were identified: a MCA period of generally wetter conditions (AD 750-1100) and a LIA period of overall drier conditions (~AD 1100-1900) during a southerly and northerly shifted SWW respectively, driven by solar variability and polar cell strengthening.

Ingeniero Civil de Minas / El estudio del comportamiento de roca intacta es el punto de partida para poder realizar análisis a escala de macizo rocoso. Es por esto que se han realizado grandes esfuerzos para replicar y validar dicho comportamiento mediante el modelamiento numérico. Aquí es donde aparece el programa de elementos discretos PFC3D, el cual replica a la roca intacta mediante esferas rígidas unidas entre sí por modelos de contactos, cuyo comportamiento depende de micro-parámetros. El modelo de contactos utilizado últimamente para realizar los ensayos con este programa tiene por nombre Enhanced Bonded Particle Model, el cual presenta una serie de deficiencias. De esta manera se trabajó en la creación de un nuevo modelo llamado Flat Joint Model, con la finalidad de tratar de superar las falencias que presenta el Enhanced BPM. De esto nace el objetivo principal de este trabajo, el cual consiste en calibrar este nuevo modelo de contacto, de manera de representar el comportamiento de la roca intacta, que en este caso corresponde a la roca Westerly granite, y poder así comparar los resultados obtenidos por ambos modelos. Para lograr la calibración del Flat Joint Model, y tener un punto de comparación con datos de laboratorio, se extraen desde la literatura una serie de datos experimentales de diversos autores que realizaron una serie de ensayos de roca a muestras de granito que llevan por nombre Westerly granite. Además se cuenta con los resultados de simulaciones hechas con el modelo Enhanced Bonded Particle Model. Los resultados de las simulaciones hechas con el Flat Joint Model, luego de haber sido calibrado, nos dicen que este modelo replica con mayor exactitud los parámetros elásticos y de resistencia en el ensayo de compresión uniaxial y de tracción directa, como también representa de mejor manera la envolvente de falla experimental de la roca, sobre todo a confinamientos bajo los 60 [MPa]. Además se resuelve en parte una de las deficiencias del modelo Enhanced BPM, el cual no es capaz de replicar los valores de la razón de Poisson de la roca obteniendo resultados muy por debajo a los experimentales (diferencias del orden de 86%). Finalmente se concluye que el FJM es mejor modelo de contactos que el Enhanced BPM debido a que es capaz de replicar un comportamiento post-peak de la roca (comportamiento frágil), lo cual era la gran deficiencia del primer modelo. Si bien no se logra representar la fragilidad de la roca a grandes confinamientos, es un gran avance que se tengan comportamientos frágiles aún a 30 [MPa] de confinamiento, siendo que en el Enhanced BPM, a confinamientos de 5 [MPa] ya se presenta una respuesta dúctil de la curva esfuerzo-deformación.

Les coups de vent d’ouest (WWEs) issu de la variabilité synoptique atmosphérique jouent un rôle crucial dans les irrégularités d’ENSO en contribuant au déclenchement et au développement de sa phase chaude, El Niño. Les WWEs sont des événements haute fréquence peu prévisibles et dont les origines atmosphériques restent encore débattues. Dans le but d’affiner la prévisibilité d’ENSO, cette thèse caractérise la part stochastique de la part prévisible des WWEs ainsi que de leur réponse océanique et couplée. Dans une première partie, j’ai relié l’occurrence et les caractéristiques des coups de vent à des phénomènes de grande échelle comme l'oscillation de Madden-Julian, les ondes de Rossby atmosphériques et ENSO, à partir d’analyse d’observations. Ensuite, la forte sensibilité de la réponse océanique des WWEs à l’état de l’océan a été mise en évidence grâce à une série de simulations océaniques forcées. Finalement, une simulation d’ensemble réalisée avec un modèle couplé océan-atmosphère a permis d'explorer le rôle des WWEs dans l’évolution contrastée des années 1997,2014 et 2015 qui présentaient des conditions similaires et favorables au déclenchement d'El Niño. Les résultats de ce travail montrent que la stochasticité des WWEs aboutit à une limitation intrinsèque de la prévisibilité des caractéristiques d’El Niño. / Equatorial Pacific Westerly Wind Events (WWEs) impact ENSO evolution through their oceanic response and strongly contribute to its irregularities. WWEs are characterized by episodes of anomalous, short-lived, strong westerlies developing over the western Pacific warm pool. This thesis characterize the atmospheric origins and the oceanic and coupled impacts of these events in order to improve ENSO prediction. First, we show that, at intraseasonnal timescale, the Madden-Julian oscillation and the convectively coupled Rossby waves provide favourable conditions for the occurence of WWEs and confirm their modulation by ENSO at interannual timescale. Oceanic simulation with idealized forcing further allow characterizing and understanding the modulation of the SST response to WWE by the oceanic background state. Finally, The role of WWEs in the contrasted evolution of El Niño in 1997,2014 and 2015, which exhibited favourable conditions for El Niño to develop, is explored in ensemble simulations using a coupled ocean-atmosphere model. It is shown that the stochasticity of the WWEs acts as a strong limitation for ENSO predictability.