Extratropical cyclones (ETCs) are a common feature of mid- and high-latitudes which, on a large scale, are a primary mechanism by which heat and moisture are transported from equator to pole. ETCs also exert a major impact at smaller scales. Communities along the western coast of Alaska face many types of impacts generated by the winds associated with ETCs, including storm surges, sea water intrusion into fresh water stores, and coastal erosion. Such “strong wind events”, which can occur independent of an ETC, can also generate hazardous sea states and associated impacts on shipping. With no roads, coastal Alaska relies heavily on marine and air transportation. Hazards posed to marine and air travel are often related to two main types of weather: wind and fog. Consultations with stakeholders in the marine transportation community have indicated more precisely specific aspects of poor weather, such as high wind events, that are problematic, including the idea that the periods between strong wind events, defined as lull periods, represent an important metric when planning travel between points of safe harbour. Three separate studies of storminess metrics in the North Pacific and Alaskan regions are presented. The first study presents both a comparison of two storm identification and tracking algorithms and an evaluation of the general characteristics of extratropical cyclones for the North Pacific as portrayed in two reanalyses. The second study applies a modified wind event identification algorithm to reanalysis data to evaluate the spatial climatological patterns of wind events in the circum-Arctic. The third study tests the statistical relationships and predictability of two measures of storm activity - cyclone track density (TDEN) and wind event frequency - in the North Pacific using teleconnection indices exhibiting local influence. The first study showed that the general patterns and trends of cyclone characteristics are similar between the two methods, though with increased values of cyclogenesis density, cyclolysis density, and track density when using the relative vorticity based method. A comparison between storm tracks for NCEP1 and the 56-member ensemble of the Twentieth Century Reanalysis v2 (20CR) shows distinct differences between the 20CR and NCEP1 mean climatology for main storminess indicators. The second study evaluated the spatial and temporal characteristics of wind events and introduced a novel indicator that characterizes periods of favorable weather between strong wind events that last 48-hours or longer, termed lull events. Lull periods were found to be an important consideration for northern marine operations – both economic and subsistence. Additionally, combinations of lull and wind event indicators, termed lull/storm winds (LSW), were analyzed and showed that preferred areas of wind events and lull events are not always spatially coherent. The third study tested the statistical relationships and predictability of two measures of storm activity - cyclone track density (TDEN) and wind event frequency - in the North Pacific using teleconnection indices with local influence for the winter period of 1950 - 2012. Two statistical modeling techniques are applied to evaluate linear and non-linear methods of prediction for the region. For both measures of storm activity, the North Pacific index, Niño 3.4 index, and the AO index were found to be the best predictors. Using a 23-year hindcast period (1980 – 2012), the region of highest wind event anomaly prediction skill is located in the western Bering Sea, with hindcast correlation values as high as +0.5 and root mean squared skill scores (RMSESS) 25% higher than climatology. Highest TDEN predictive skill from the 23-year hindcast is found in the southeast region of the North Pacific, near the California coastline, with correlation and RMSESS as high as +0.7 and 25 - 30%, respectively. / Graduate

Despite advancements in glass facade systems and rigorous building codes requirements, glass façades often sustain damage or breaches during extreme wind events. This study aims to establish a framework that identifies a multitude of characteristics in common glass façade systems that may contribute to performance of a buildings with glass facades during natural wind disasters. Through a comprehensive analysis of damaged structures, common characteristics susceptible to damage after such events were identified. These characteristics served as a catalyst to explore other characteristic that may affect the performance of a structure's facade during extreme wind events. The identified characteristics were categorized into three groups: architectural components, structural components, and environmental. Proposed quantifiable methods aim to obtain qualitative measurements of existing glass facades. In the end, this thesis contributes to the broader goal of understanding the performance of glass facades during extreme wind events. / Master of Science / Despite advances in building design and construction standards, glass on buildings remain vulnerable to damage during severe windstorms. This study aims to develop a system that identifies key factors that contribute to a building's glass façade system during natural disasters like hurricanes and tornadoes. By analyzing data from damaged structures, common characteristics were identified that are prone to damage during extreme wind events. These findings have led to explore other factors that may impact a facade's performance in such situations. These factors were categorized into three main groups: architectural features, structural elements, and environmental considerations. The proposed methods obtain a numeral value that is measured from existing structures. Ultimately, this research aims to improve the understanding of glass facades from challenges posed by severe weather events.

In this study, we use a hazard-based modeling as an alternative statistical framework to time series methods as applied to climate data. Data collected from the Kentucky Mesonet will be used to study the distributional properties of the duration of high and low-energy wind events relative to an arbitrary threshold. Our objectiveswere to fit bathtub models proposed in literature, propose a generalized bathtub model, apply these models to Kentucky Mesonet data, and make recommendations as to feasibility of wind power generation. Using two different thresholds (1.8 and 10 mph respectively), results show that the Hjorth bathtub model consistently performed better than all other models considered with coefficient of R-squared values at 0.95 or higher. However, fewer sites and months could be included in the analysis when we increased our threshold to 10 mph. Based on a 10 mph threshold, Bowling Green (FARM), Hopkinsville (PGHL), and Columbia (CMBA) posted the top 3 wind duration times in February of 2009. Further studies needed to establish long-term trends.

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.

<p>Lateral loads on buildings, either caused by wind or seismic events, are resisted primarily by the in-plane strength and stiffness of the walls oriented parallel to the direction of the applied load. The concern associated with relying on unreinforced masonry (URM) shear walls to transfer the load to the foundation is that the typical modes of failure are characterized by brittle behaviour, with rapid decreases in capacity and very limited deformations once the ultimate load is reached.</p> <p>Traditional strengthening techniques have several undesirable properties, including being labour intensive and adding weight to the structure. Past research has shown that fibre reinforced polymer (FRP) reinforcement is an effective method of increasing both the strength and ductility of URM. One of the most desirable properties of FRP is that it has a high strength to weight ratio.</p> <p>An experimental investigation was conducted to study the influence of surfacebonded fibreglass laminates on the sliding shear resistance of URM. The investigation was conducted in three phases:</p> <p>1 Phase One: Analyzing the performance of five different test specimen shapes retrofitted with GFRP to determine the most adequate configuration for further shear slip tests. The data was also of direct use as an evaluation of strength and behaviour of FRP reinforced masonry subjected to shear-slip failure. Thirty-seven shear slip specimens were tested to failure. The average increase in shear strength ranged from 3 .1 to 7. 7 times that of the unretrofitted counterparts.</p> <p>2 Phase Two: Assessing the feasibility of obtaining two sets to data from each test specimen.</p> <p>3 Phase Three: Assessing the shear-slip strength and behaviour of URM reinforced with fibreglass mesh, of different weights, adhered at two different orientations to the bed joint slip planes (0°190°, ±45°) using a modified mortar parging. Twenty-one shear slip specimens were tested to failure. Typically, for any given mesh weight, orienting the fibres at ±45° resulted in failure characterized by higher strength and less ductility compared to tests with fibres oriented at 0°190° to the bed joints. At ±45° orientation, the fibres ruptured at failure. When the mesh was oriented at 0°190°, the fibres pulled out of the cement parging, which limited the strength, but enabled specimens to undergo large deformations while maintaining fairly constant residual capacity.</p> / Master of Engineering (ME)