Dissertations / Theses on the topic 'Global and regional models'

Les vagues de surface générées par le vent, généralement appelées houle ou mer de vent, sont omniprésents à la surface de I'océan. Ils sont et ont des périodes variant entre 2 et 25 secondes et de longueur d'onde variant de quelques mètres à plusieurs centaines de mètres. Il existe aussi des ondes plus longues et, à plus basse fréquence appelés ondes infragravitaires (IG), qui sont associés aux vagues courtes, générées par le vent. Ces ondes ont des périodes dominantes comprise entre 30 secondes et 10 minutes et, quand ils se propagent librement, avec des longueurs d'ondes pouvant atteindre plusieurs dizaines de kilomètres. En dehors de la zone de surf, I'amplitude verticale de ces ondes infragravitaires est de I'ordre de 1 à 10 cm, tandis que I'amplitude des vagues courtes est de I'ordre de 1-10 m.Malgré leurs petites échelles d'amplitude, ces ondes infragravitaires peuvent avoir une importance non-négligeable dans certaines situations. Elles peuvent par exemple exciter des phénomènes de seiches dans les ports et mettre en résonance des structures en mer et des lames de glaces dansI'Arctique ou I'Antarctique. Le champ d'ondes infragravitaires constituera probablement aussi une fraction significative du signal mesuré par la future mission du satellite Surface Water Ocean Topography (SWOT). Ce champ d'onde infragravitaire devra être caractérisé pour atteindre la précision attendue sur les mesures de hauteur de mer dynamiques. Il est probable que la précision visée ci-dessus ne soit pas possible pour les forts états de mer avec de longues houles. L'un des objectifs de cette thèse était de fournir une première quantification de ces incertitudes associées.Au-delà de la mission SWOT, la quantification du champ d'ondes IG est un problème clé pour la compréhension de plusieurs autres phénomènes géophysiques tels que la compréhension des microséismes
Wind-generated surface gravity waves are ubiquitous at the ocean surface. Their period varies between 2 and 25 seconds, with wavelength varying between a few meters to several hundreds of meters. Longer and, lower frequency surface gravity waves, called infragravity (IG) waves, are associated to these short, high frequency wind-generated waves. These infragravity waves have dominant periods comprised between 30 seconds and 10 minutes, and, when they propagate freely, with horizontal wavelengths of up to tens of kilometres, as given by the linear surface gravity wave dispersion relation. Outside of surf zones, the vertical amplitude of these infragravity waves is of the order of 1-10 cm, while the amplitude of wind-generated waves is of the order of 1-10 m.Given the length scales of the infragravity wavelengths, and despite the fact that the infragravity wave field exhibits much smaller vertical amplitudes than the high frequency wind-driven waves, the infragravity wave field will be a significant fraction the signal measured by the future Surface Water Ocean Topography satellite (SWOT) mission. This infragravity wave field will have to be characterized in order to achieve the expected precision on dynamic height measurements. It appears likely that the above mentioned precision will not be feasible for high sea states and long and steep swells. One of the aims of this thesis was to provide a first quantification of these associated uncertainties. Beyond the SWOT mission, the quantification of the IG wave field is a key problem for the understanding of several geophysical phenomena, such as the understanding of microseisms and ice shelves break up

Explosive volcanic eruptions can eject large quantities of particulate matter that, along with other aerosol droplets and trace gases, are carried upwards into the atmosphere by the buoyant eruption column and then dispersed by winds aloft. The presence in the atmosphere of volcanic ash is a sporadic yet important factor that can threaten human health, affect the urban built environment, disrupt aerial navigation and, for very large eruptions, alter both atmospheric composition and chemistry. Once volcanic ash is injected into the atmosphere, it can be transported over great distances, even circumnavigating the entire planet. Volcanic ash modeling systems are used to simulate the atmospheric dispersion of volcanic ash and to generate operational short-term forecasts to support civil aviation and emergency management. The efficiency of response and mitigation actions is directly associated to the accuracy of the volcanic ash cloud detection. Volcanic ash modeling systems normally require an emission or source term model to characterize the eruption column; a dispersal model to simulate the atmospheric transport, dispersion and ground deposition of ash particles; and a meteorological model for the description of the atmospheric conditions. Traditional forecasts for volcanic ash build on off-line coupled modeling systems, where meteorological variables are only updated at the specified coupling intervals. Although this approach is computationally advantageous is some cases, there is a concern that it can lead to a number of accuracy issues and limitations that can be corrected by on-line modeling strategies. Despite these concerns, to date, no on-line coupled model is available for operational forecast of volcanic ash. In addition, the quantification of the limitations associated to the off-line systems has received no attention. This Ph.D. thesis describes and evaluates NMMB-MONARCH-ASH, a novel fully coupled on-line multiscale meteorological and atmospheric transport model designed to predict ash cloud trajectories, concentration of ash at relevant flight levels, and the expected deposit thickness for both regional and global domains in research and operational set-ups. The first activity targeted a model validation against several well-characterized events including, the Mt. Etna 2001, Eyjafjallajökull 2010, and Cordón Caulle 2011 eruptions. The model has shown to be robust, scalable, and capable to reproduce the spatial and temporal dispersal variability of the ash cloud and tephra deposits, showing promising results and improving the performance from well-known off-line operational models. The second activity quantified the model shortcomings and systematic errors associated to traditional off-line forecasts employed in operational set-ups. NMMB-MONARCH-ASH demonstrated that off-line forecasts could fail to reproduce up to 45-70% of the ash cloud of an on-line forecast, considered to be the best estimate of the true outcome. The uncertainty associated to off-line systems was found to be as relevant (same order of magnitude) as those uncertainties attributed to the source term. The third activity focused on a global application of NMMB-MONARCH-ASH to analyze the potential impacts of ash dispersal from Antarctic volcanoes. Numerical simulations suggested that volcanic ash emitted from Antarctic volcanoes could potentially encircle the globe, leading to significant consequences for global aviation safety. The last activity included a novel computational inversion method to account, for the first time, for the Plinian and co-ignimbrite phases of the 39 ka Campanian Ignimbrite super-eruption. This particular application employed the off-line coupled FALL3D model, found to be more suitable from a computational point of view. The outcome of this Ph.D. thesis encourages operational groups responsible for real-time advisories for aviation to consider using computationally efficient on-line coupled ash dispersal models.
Las erupciones volcánicas explosivas pueden emitir una gran cantidad de material que, junto con otros aerosoles y gases traza, son inyectados en la atmósfera por la columna eruptiva para luego ser dispersados por los vientos en altura. La presencia en la atmósfera de cenizas volcánicas es un factor esporádico aunque importante, que puede llegar a amenazar la salud humana, afectar las infraestructuras urbanas, interrumpir la navegación aérea y, en el caso de grandes erupciones, alterar la composición atmosférica y química. Una vez en la atmósfera, la ceniza puede ser transportada a grandes distancias, llegando incluso a circunnavegar todo el planeta. Los sistemas de modelado de cenizas volcánicas se utilizan para simular la dispersión atmosférica de estas partículas, y para generar pronósticos operacionales a corto plazo empleados para dar soporte a la aviación civil y a la gestión de emergencias. La eficacia para responder a estos eventos está directamente asociada a la precisión de los modelos de transporte de cenizas volcánicas. Los sistemas de modelado de cenizas volcánicas requieren de un modelo de emisión de partículas para la caracterización de la columna eruptiva; un modelo de dispersión para la simulación del transporte atmosférico y la deposición de cenizas; y de un modelo meteorológico para la descripción de las condiciones atmosféricas. Los pronósticos tradicionales se basan en sistemas de modelado desacoplados (off-line), donde las variables meteorológicas sólo se actualizan a intervalos de tiempo especificados. Aunque este enfoque presenta ventajas desde el punto de vista computacional, existe la preocupación de que puede estar asociado a limitaciones y problemas de precisión que, por el contrario, pueden ser corregidos mediante estrategias de modelado acoplado (on-line). A pesar de estas preocupaciones, hasta la fecha no hay un modelo acoplado on-line disponible para el pronóstico operativo de la cenizas volcánicas. Además, tampoco existe una cuantificación de las limitaciones asociadas a los sistemas off-line. Este doctorado describe y evalúa NMMB-MONARCH-ASH, un modelo de transporte meteorológico y atmosférico multiescalar (regional/global) completamente acoplado on-line, para su uso en investigación y predicción operacional. El modelo está diseñado para predecir trayectorias de cenizas volcánicas, concentración de ceniza en niveles de vuelo (flight levels), y el correspondiente espesor de depósito. La primera actividad de esta tesis se centra en la validación de modelo mediante erupciones bien caracterizadas (Mt. Etna 2001, Eyjafjallajökull 2010, y del Cordón Caulle 2011). El modelo ha demostrado ser robusto, escalable y capaz de reproducir la variabilidad de la dispersión espacial y temporal de los depósitos y de las nubes de ceniza, ostrando resultados prometedores y mejorando el rendimiento de modelos operacionales. La segunda actividad cuantifica los errores sistemáticos asociados a los pronósticos off-line. NMMB-MONARCH-ASH demuestra que estps pronósticos podrían no reproducir hasta un 45-70% de la nube de cenizas de un pronóstico on-line, considerado éste último como la mejor estimación de la realidad. Esta actividad concluye que la incertidumbre asociada a los sistemas off-line puede llegar a ser tan relevante como aquellas incertidumbres atribuidas al término fuente. La tercera actividad se centra en una aplicación global de NMMB-MONARCH-ASH para analizar los posibles impactos asociados a la dispersión de ceniza de volcanes antárticos. Los resultados alertan de las posibles consequencias de estas erupciones en la aviación a nivel mundial . La última actividad incluye un nuevo método de inversión computacional para identificar, por primera vez, las fases Pliniana y coignimbrita de la super-erupción de la Ignimbrita Campaniana (39 ka) con FALL3D. Los resultados de este Ph.D. alientan a considerar el uso de modelos acoplados on-line para generar pronósticos operacionales de ceniza volcánica.

This thesis explores the ability of global climate models (GCMs) to simulate observed conditions at regional scales by examining probability density functions (PDFs) of daily minimum temperature (Tmin), maximum temperature (Tmax) and precipitation (P). Two new measures of model skill are proposed using PDFs of observed and modelled data. The first metric (Sscore) compares the amount of overlap between the two PDFs. The second metric (Tailskill) is the weighted difference between the PDF tails, where extreme events are represented. The resulting measures of skill are used to differentiate, at a regional scale, between weaker and stronger models. It is investigated whether the weaker models bias future projections given by multi-model ensembles, increasing the uncertainty in the range of projected values and the change from the 20th Century. The Sscore is demonstrated to be robust against inhomogenities found in highdensity Australian datasets, and is a simple and quantitative measure of how well each GCM can simulate all observed events. This methodology is executed for twelve Australian regions of varying climates for all Intergovernmental Panel on Climate Change 4th Assessment Report models for which daily data was available for 1961-2000. Across Tmin, Tmax and P some GCMs perform well, demonstrating that some GCMs provide credible simulations of climate at sub-continental scales. Projections of the annual and seasonal mean and yearly return values over the A2 and B1 emission scenarios are investigated. Models are omitted from an ensemble based on their ability to simulate the observed PDF at regional scales. The stronger models are generally in agreement with the change in mean values, particularly for Tmin and Tmax, though it is shown that they vary in their projections of the yearly return value at least twice as much as projections in the mean values. Lastly, a means-based evaluation method, the Sscore and the Tailskill are employed to differentiate between weaker and stronger models for projections in the 20-year return value of Tmin and Tmax. Weaker-skilled ensembles project larger increases in 20-year return values than stronger-skilled ensembles, such that in some regions for maximum temperature the ensembles are statistically significantly different. Demonstrably weaker models bias projections given by an all-model ensemble and should be excluded so the most reliable estimates of future climate can be obtained.

Includes bibliographical references
Drought is one of the natural hazards that threaten the economy of many nations, especially in Southern Africa, where many socio-economic activities depend on rain-fed agriculture. This study evaluates the capability of Regional Climate Models (RCMs) in simulating the Southern African droughts. It uses the Standardized Precipitation-Evapotranspiration Index (SPEI, computed using rainfall and temperature data) to identify 3-month droughts over Southern Africa, and compares the observed and simulated drought patterns. The observation data are from the Climate Research Unit (CRU), while the simulation data are from 10 RCMs (ARPEGE, CCLM, HIRHAM, RACMO, REMO, PRECIS, RegCM3, RCA, WRF, and CRCM) that participated in the Regional Climate Downscaling Experiment (CORDEX) project. The study also categorizes drought patterns over Southern Africa, examines the persistence and transition of these patterns, and investigates the roles of atmospheric teleconnections on the drought patterns. The results show that the drought patterns can occur in any season, but they have preference for seasons. Some droughts patterns may persist up to three seasons, while others are transient. Only about 20% of the droughts patterns are induced solely by El Niño Southern Oscillation (ENSO), other drought patterns are caused by complex interactions among the atmospheric teleconnections. The study also reveals that the Southern Africa drought pattern is generally shifting from a wet condition to a dry condition, and that the shifting can only be captured with a drought monitoring index that accounts for temperature influence on drought. Only few CORDEX RCMs simulate the Southern African droughts as observed. In this regard, the ARPEGE model shows the best simulation. The best performance may be because the stretching capability of ARPEGE helps the model to eliminate boundary condition problems, which are present in other RCMs. In ARPEGE simulations, the stretching capability would allow a better interaction between large and small scale features, and may lead to a better representation of the rain producing systems in Southern Africa. The results of the study may be applied to improve monitoring and prediction of regionally-extensive drought over Southern Africa, and to reduce the socio-economic impacts of drought in the region.

The overarching goal of this thesis is to develop a diagnostic and predictive model to quantify the estuarine CO2 dynamics across scales – from catchment to the globe – using an approach that explicitly resolves the strong physical and biogeochemical gradients typically observed in these systems.Chapter 1 provides fundamental definitions and descriptions of estuaries, as well as an assessment of their role in the global carbon cycle. It also raises the specific objectives and research questions tackled in the present study. Chapter 2 presents the rationale behind the novel modelling approach (C-GEM, Carbon-Generic Estuary Model) developed in the framework of this thesis. First, the dominant processes that control the estuarine biogeochemistry in estuaries are discussed in detail. Then, the power of reactive-transport models (RTMs) in understanding and quantifying the estuarine biogeochemical functioning is illustrated on the basis of local modelling studies. Finally, trends in estuarine biogeochemical dynamics across different geometries and environmental scenarios are briefly explored with C-GEM and results are discussed in the context of improving the modelling of estuarine carbon dynamics at regional and global scales. In Chapter 3, a detailed description of C-GEM, both in terms of structure and set-up, is provided and model’s performance is successfully evaluated through comprehensive model-data and model-model comparisons in the macro-tidal Scheldt estuary (BE/NL). In Chapter 4, C-GEM is combined with a generic set of forcing conditions and parameter values to quantify the carbon dynamics (net ecosystem metabolism, CO2 exchange at the air-water interface, carbon filtering capacity) in three idealized estuaries subject to temperate climatic conditions. Their hydro-geometrical characteristics span the wide diversity of estuarine morphological characteristics. Model results are used to upscale the estuarine CO2 dynamics under present-day conditions and to quantify the response of the estuarine filter to future atmospheric CO2, land use and climate change scenarios. In Chapter 5, C-GEM is applied to derive estimations of carbon export and CO2 outgassing from all tidal estuaries discharging in the North Sea. Overall, our results suggest that the estuarine carbon filtering capacity and the contribution of these land-ocean transition systems to the atmospheric CO2 budget might not be as high as previously thought. Finally, a conclusive chapter (Chapter 6) provides a synthesis of the key findings and arguments projected by the present research work. Moreover, recommendations are given in the light of further applications of the modelling approach developed during this thesis.
Doctorat en Sciences
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The assessment of economic variables is an important part of regional macroeconomic analyses. However, increasing integration of the markets has led to greater financial and economic interdependence between regions. Therefore, this paper uses the global vector autoregressive (GVAR) methodology, which can tackle the curse of dimensionality. Focusing in the Brazilian labor market, it has two main objectives: firstly, establishing a model accounting for the interdependencies between regions. Secondly, estimate the regional elasticity of employment in respect to the economic activity of the country. To this end, it is applied the so-called GVAR technique, which considers the interdependencies between several regions and their temporal dynamics in a multivariate framework. The model is estimated at the Brazilian mesoregion level, with 137 distinct mesoregions. The final model proved to be stable with 128 regions, 2 cointegration relationship and, and 9 regions having 1 cointegration relation. Focusing on the classical major Brazilian regions (North, Northeast, Southeast, South, Central) it is estimated that the most sensitive region is the South followed by the Northeast and the South region, while the Northern and Central regions are mostly unaffected. A long-run relationship is also estimated indicating a natural growth of 694 thousand jobs per year in Brazil.
A avaliação das variáveis econômicas é uma parte importante das análises macroeconômicas regionais. No entanto, o aumento da integração dos mercados levou a uma maior interdependência financeira e econômica entre as regiões. Portanto, este artigo usa a metodologia de vetor autoregressivo global (GVAR), que pode enfrentar a maldição da dimensionalidade. Focando no mercado de trabalho brasileiro, tem dois objetivos principais: primeiro, estabelecer um modelo levando em conta as interdependências entre as regiões. Em segundo lugar, estimar a elasticidade regional do emprego em relação à atividade econômica do país. Para este fim, é aplicada a chamada técnica GVAR, que considera as interdependências entre várias regiões e suas dinâmicas temporais em uma estrutura multivariada. O modelo é estimado no nível mesorregional brasileiro, com 137 mesorregiões distintas. O modelo final mostrou-se estável com 128 regiões, 2 relações de cointegração e, e 9 regiões com 1 relação de cointegração. Concentrando-se nas principais regiões brasileiras clássicas (Norte, Nordeste, Sudeste, Sul, Central), estima-se que a região mais sensível é o Sul, seguido pela região Nordeste e Sul, enquanto as regiões Norte e Central não são afetadas. Uma relação de longo prazo também é estimada indicando um crescimento natural de 694 mil empregos por ano no Brasil.

Wind farm assessment is a costly and time consuming process when it is planned by traditional methods such as a met mast. Therefore, new models have been established and used for the wind farm assessment to ease the process of wind farm planning. These models are Global-regional models which add to cost efficiency and time saving. There are several types of these models in the market that have different accuracy. This thesis discusses and uses in simulations Global – regional model data outputs from European Centre for Medium-Range Weather Forecasts (ECMWF), Weather Research Forecast WRF and ECMWF, which is currently producing ERA-Interim, global reanalysis of the data-rich period since 1989 .The goal of the master's thesis is to see whether it is useful and efficient to use Global – regional weather model data such as the Era Interim Global Reanalysis Model data for wind assessment by comparing it with the real data series (met mast) located in Maglarp, in the south of Sweden.The comparison shows that in that specific area (hindcast) at Maglarp, in the south of Sweden, very promising results for planning a wind farm for a 100m, 120m and 38m heights.

Climate variability is an important characteristic of regional climate, and a subject to significant control from teleconnections. An extended diagnosis of the capacity of climate models to represent remote controls of regional climate (teleconnections) is vital for assessing model-based predictions of climate variability, understanding uncertainty in climate projections and model development. An important driver of climate variability for Africa is the sea surface temperature (SST) - rainfall teleconnection, such as the El Ni˜no/Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). In this study, an assessment of the teleconnection between tropical SSTs and Eastern African rainfall in global and regional climate models is presented, with particular attention paid to the propagation of large-scale teleconnection signals (as represented by model reanalyses and Coupled Global Climate models (CGCMs)) into the domain of the Regional Climate Models (RCMs). The teleconnection-rainfall relationship with the Eastern Africa region is assessed in two rainfall seasons (June-July-August-September and October-November- December) under present and future periods. Evaluation runs (RCMs driven by reanalysis datasets) and historical simulations (RCMs driven by CGCMs) are assessed to quantify the ability of the models to capture the teleconnection relationship. The future analysis is performed for two Representative Concentration Pathway scenarios (RCP4.5 and RCP8.5) to assess future change in this relationship as a result of global warming. Using ERA-interim reanalysis as perfect boundary conditions, the RCMs adequately simulate the spatial and temporal distribution of rainfall in comparison with observations, although the model performance varies locally and seasonally within the region. Furthermore, the RCMs correctly capture the magnitude and spatial extent regional-scale seasonal rainfall anomalies associated with large-scale oceanic modes (ENSO and IOD). When the lateral boundary conditions are provided by CGCMs, RCMs barely capture the regional teleconnection patterns associated with large-scale modes, and mostly depend on the selection of the driving CGCM. Comparison of the CGCM-driven RCM simulations with the reanalysis-driven RCM simulations revealed that most of the errors in teleconnection found in the RCM simulations are inherited from the host CGCMs. The ERA-Interim driven downscaled results show better agreement with observed spatial teleconnection patterns than the CGCM driven downscaled results. Analysis of the CGCMs and corresponding downscaled results showed that in most cases both the CGCM and the corresponding downscaled simulations had similar teleconnection patterns, but in some cases the RCM results diverge to those of the driving CGCM results. It has been demonstrated that similarities in SST-rainfall teleconnection patterns between the RCM simulations and respective driving CGCM simulations are noted over the equatorial and southern part of the region during OND season, where the rainfall is primarily controlled by large-scale (synoptic-scale) features, with the RCMs maintaining the overall regional patterns from the forcing models. Di↵erences in RCM simulations from corresponding driving simulations are noted mainly over northern part of the domain during JJAS, which is most likely related to mesoscale processes that are not resolved by CGCMs. Looking at the model projections of the future, although the spatial pattern of teleconnections between ENSO/IOD and rainfall still persist, important changes in the strength of the teleconnection have been found. During JJAS, ENSO is an important driver of rainfall variability in the northern parts of the region where dry anomalies are associated with El Ni˜no and wetter anomalies with La Ni˜na. Both regional and global ensemble projections show higher rainfall during La Ni˜na and lower rainfall during El Ni˜no over the northern part of the region compared to the present period. During OND, the teleconnection between ENSO/IOD and rainfall is projected to strengthen (weaken) over Eastern horn of Africa (southern parts of the region) compared to the present period. This implies heavy seasonal rains associated with positive phases of ENSO and IOD will increase in future across the Eastern horn of Africa. The change OND rainfall teleconnections are stronger and also more consistent between the models and scenarios as compared to the change in JJAS teleconnections. These findings have an important implication for the water and agricultural managers and policies in the region to tackle the anticipated droughts and floods associated anthropogenic climate change. Finally, the analysis demonstrated that the largest source of uncertainty in the regional climate model simulations in the context of teleconnective forcing of rainfall over Eastern Africa is the choice of CGCM used to force the RCMs, reinforcing the understanding that the use of a single GCM to downscale climate predictions/projections and using the downscaled product for assessment of climate change projections is insufficient. Simulations from multiple RCMs nested in more than one GCM, as is undertaken in the Coordinated Regional Downscaling Experiment (CORDEX), are needed to characterize the uncertainty and provide estimates of likely ranges of future regional climate changes.

Accurate simulations of the global radiative impact of anthropogenic emissions must employ a tropospheric chemistry model that predicts realistic distributions of aerosols of all types. The need for a such a comprehensive yet computationally efficient tropospheric chemistry model is addressed in this research via systematic development of the various sub-models/mechanisms representing the gas-, aerosol-, and cloud-phase chemistries. The gas-phase model encompasses three tropospheric chemical regimes - background and urban, continental rural, and remote marine. The background and urban gas-phase mechanism is based on the paradigm of the Carbon Bond approach, modified for global-scale applications. The rural gas-phase chemistry includes highly condensed isoprene and a-pinene reactions. The isoprene photooxidation scheme is adapted for the present model from an available mechanism in the literature, while an a-pinene photooxidation mechanism, capable of predicting secondary organic aerosol formation, is developed for the first time from the available kinetic and product formation data. The remote marine gas- phase chemistry includes a highly condensed dimethylsulfide (DMS) photooxidation mechanism, based on a comprehensive scheme available in the literature. The proposed DMS mechanism can successfully explain the observed latitudinal variation in the ratios of methanesulfonic acid to non-sea-salt sulfate concentrations. A highly efficient dynamic aerosol growth model is developed for condensing inorganic gases. Algorithms are presented for calculating equilibrium surface concentrations over dry and wet multicomponent aerosols containing sulfate, nitrate, chloride, ammonium, and sodium. This alternative model is capable of predictions as accurate for completely dissolved aerosols, and more accurate for completely dry aerosols than some of the similar models available in the literature. For cloud processes, gas to liquid mass-transfer limitations to aqueous-phase reactions within cloud droplets are examined for all absorbing species by using the two-film model coupled with a comprehensive gas and aqueous-phase reaction mechanisms. Results indicate appreciable limitations only for the OH, HO2, and NO3 radicals. Subsequently, an accurate highly condensed aqueous-phase mechanism is derived for global-scale applications.
Ph. D.

Aerosols have an inhomogeneous distribution across the globe because of their short lifetimes in the atmosphere. They impose a localised radiative forcing close to their emission source that is effective at driving circulation changes and influencing the hydrological cycle. One such type of circulation that has recently been suggested to be affected by aerosols is the South Asian summer monsoon, which provides 80% of annual rainfall to over a billion people during the summer months. I used the UK Met Office HadGEM3 coupled global climate model to investigate, for the first time, the centennial-scale South Asian precipitation responses to removing regional anthropogenic sulphur dioxide emissions. This study is unique since these experiments have never been attempted on a scale that is multi-regional, centennial and in a fully coupled ocean-atmosphere model setup. Despite the imposed localised heating in my experiments resulting from emissions removals over the United States, Europe, East Asia, South Asia or the northern mid-latitudes as a whole, the large-scale spatial pattern and magnitude of the precipitation response over South Asia was similar for all experiments. This was due to the ocean responding to the atmosphere enabling the full response to be realised and the ocean dynamics driving a structurally similar global climate response. The sum of the responses from the experiments where the emissions are removed from the United States, Europe and East Asia resemble the response seen in the experiment where emissions are removed in the entire northern mid-latitude band, suggesting that the response is roughly linear, with East Asia being the largest contributor to the response. East Asia’s proximity to South Asia meant that it was more effective at influencing the land-sea thermal contrast, pressure gradients, and therefore the local monsoon circulation itself. On the other hand, local emissions removals, i.e. over South Asia itself, led to decreases in precipitation over central and northern India, a result not seen in any other experiment. Moreover, the response of the circulation was still found to be the main driver of the response in this case, despite changes to the clouds making them thinner and less reflective. In the future, further work is warranted to allow for comparisons with other coupled ocean-atmosphere models performing similar multi-regional experiments, to enhance confidence in our results and to further our understanding of the processes involved. Similar experiments can also be performed to explore the role of other short-lived pollutants, such as tropospheric ozone. The insight provided could prove invaluable for informing emissions reduction policies and for understanding the implications for short-term regional climate prediction.

Orientadores: João Francisco Galera Monico, Luiz Danilo Damasceno Ferreira
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciencias da Terra, Programa de Pós-Graduaçao em Ciências Geodésicas
Resumo: A maior fonte de erro no posicionamento e navegação com GPS, na ausência da disponibilidade seletiva (SA), é devida à refração ionosférica. Seu efeito causa um atraso no código e avanço na fase, de uma mesma quantidade. A magnitude desse erro é afetada pelo movimento diurno do sol, estação do ano, ciclo solar, localização geográfica do receptor e campo magnético da Terra. Como é bem conhecido, o efeito sistemático provocado pela ionosfera é o principal fator limitante no posicionamento de precisão, quando se utilizam receptores de uma freqüência, quer seja no posicionamento por ponto ou no posicionamento relativo de linhas-base médias e longas. Um modelo representado pela série do tipo de Fourier foi implementado e os parâmetros estimados, a partir de dados coletados pelas estações ativas da RBMC (Rede Brasileira de Monitoramento Contínuo dos Satélites GPS). Os dados de entrada do modelo podem ser as observáveis pseudodistâncias, pseudodistâncias filtradas pelas fases das portadoras ou fase das portadoras, coletadas nas portadoras Li e L2. Controle de qualidade baseado no teste estatístico Qui-quadrado (%) foi implementado para a análise da qualidade do ajustamento, bem como o teste de significância dos parâmetros, com o objetivo de validar os coeficientes da série. As observáveis pseudodistâncias filtradas pelas fases das portadoras proporcionaram parâmetros com melhor precisão. Experimentos foram realizados no Brasil, usando dados coletados com receptores de dupla freqüência. A fim de validar o modelo, valores estimados para as coordenadas de algumas estações de referências foram comparados com os considerados verdadeiros. Para o posicionamento por ponto, foram consideradas como valores verdadeiros as coordenadas conhecidas da estação. Já no relativo, consideraram-se as coordenadas obtidas, a partir do processamento da combinação linear livre do efeito da ionosfera. As discrepâncias em relação aos valores considerados verdadeiros indicaram uma redução do erro, em média, da ordem de 80,7% e 41,7%, respectivamente, para o posicionamento por ponto e relativo de linhas de base entre 10 km e 215 km. Estes resultados indicam que mais pesquisas devem ser realizadas, a fim de prover suporte aos usuários de receptores GPS de uma freqüência, necessitando de realizar posicionamento relativo. Porém, no posicionamento por ponto, os resultados proporcionaram discrepâncias da ordem de 1 (um) metro para as coordenadas cartesianas, o que mostra a potencialidade do modelo.
Abstract: The largest error source in the positioning and navigation with GPS, in the absence of the selective availability (SA), is due to the ionospheric refraction. Its effects cause code delay and phase advance, of the same amount. The magnitude of this error is affected with time of day, season, solar cycle, geographical location of the receiver and magnetic field of the Earth. As it is well known, the ionosphere is the main drawback for high accuracy positioning when using single frequency receivers either for point positioning or relative positioning of medium and long baselines. The effect of the ionosphere is investigated in the determination of point positioning and relative positioning using single frequency data. A model represented by a Fourier series type was implemented and the parameter estimated from data collected by the active stations of RBMC (Brazilian Network for Continuous Monitoring of GPS satellites). The model data input can be the pseudo range, pseudo range filtered by carrier phase or carrier phase observables, collected by both carriers, L1 and L2. Quality control based on the Chi-square (%2) statistical test was implemented for the analysis the quality of the adjustment, as well as the parameter significance test, with the objective to validate the estimated parameters of the series. The observables pseudo range filtered by carrier phase provided parameters with better precision. Experiments were carried out in Brazil, using data collected with dual frequencies receivers. In order to validate the model, the estimated values for coordinates station were compared with "ground truth". For point positioning the known coordinates of the station were considered as "ground truth". In the relative positioning the coordinates obtained by processing the ionospheric free combination were the "ground truth". The discrepancies - "ground truth" minus estimated value - indicated a reduction better than 80,7% and 41,7% respectively, for the point positioning and relative positioning of baselines ranging from 10 km to 215 km. These results give an indication that more research has to be carried in order to provide support to the single frequency GPS users, who need to realize relative positioning. However, in the point positioning, the results provided discrepancies better than 1 m for the cartesian coordinates, indicating the potentiality of the model.

Neste trabalho foi investigado o impacto do desmatamento e aquecimento global futuro no clima e distribuição dos biomas sobre América do Sul usando um modelo climático regional (RCM). Para este propósito, o modelo RegCM4 foi rodado forçado com dados da reanálise ERA-Interim para o período de 1989-1999 (11 anos) (experimento controle, CTRL). Uma metodologia para gerar pseudo-cenários de mudança climática com um RCM foi utilizada. Três experimentos de sensibilidade foram realizados: pseudo-aquecimento (AQ), desmatamento (DMT), e pseudo-aquecimento + desmatamento (AQ+DMT). Para comparação o RegCM4 foi rodado forçado com integrações do AOGCM ECHAM5/MPI-OM para o clima presente (1989-1999) (RF) e clima futuro (2089-2099) (FUT) sob o cenário A1B do IPCC. Os resultados mostraram que as simulações para o clima presente em ambos CTRL e RF concordaram com as observações. A distribuição dos biomas mostraram similaridades e diferenças usando os índices de Budyko e UNEP. Em geral o modelo reproduziu a distribuição dos biomas comparado com as observações. O CTRL simulou melhor a distribuição dos biomas que o RF. As simulações para o pseudo-cenário de mudança climática (AQ e FUT) concordaram com outros estudos de mudanças climáticas futuras com RCMs e AOGCM, que indicaram futuro aquecimento, aumento de precipitação no sudeste da América do Sul, Equador e Peru e diminuição na Amazônia central e leste. A distribuição dos biomas sobre a América do Sul no pseudo-cenário de mudança climática mostrou um aumento da aridez no continente usando ambos os índices. No experimento AQ porções da floresta amazônica foram substituídas por áreas de terra seca (24,2\% para o índice UNEP e 3,4\% para o índice Budyko). A zona semi-árida no nordeste do Brasil alcançou o interior do norte do Brasil (21\% dos regimes de terra seca sub-úmido seco poderiam ser ocupados por áreas de regime semi-árido para o índice UNEP e 1\% para o índice Budyko). Os resultados para o experimento DMT mostraram que o desmatamento pode ter grande influência localmente (15\% do aquecimento de quando o pseudo aquecimento foi incluído conjuntamente). O maior aumento da temperatura de superfície ocorreu no sul da Amazônia (+0.6$°$C) enquanto no norte e centro da Amazônia uma diminuição da temperatura foi notado (maior diminuição de -0.9$°$C). Quando o pseudo-aquecimento foi considerado conjuntamente (AQ+DMT) as mudanças na temperatura de superfície aumentaram muito em relação ao caso de somente desmatamento e o aquecimento ocorreu na Amazônia toda (maior aumento de +4$°$C). As mudanças na distribuição dos biomas usando os índices de Budyko e UNEP estiveram em concordância. Quando o pseudo-aquecimento foi incluído a aridez aumentou na maior parte da Amazônia comparado com o caso de desmatamento. O maior aumento da aridez ocorreu no norte da Amazônia (20\% para o índice Budyko e 37,6\% para o índice UNEP) enquanto este ocorreu no sul da Amazônia para o caso de somente desmatamento (22\% para ambos os índices Budyko e UNEP). Os resultados mostraram que embora os índices Budyko e UNEP apresentaram potencialidades e limitações em representar a distribuição dos biomas para o clima presente e pseudo-cenário de mudança climática, as mudanças na distribuição dos biomas devido ao pseudo-cenário de aquecimento global foram maiores usando o índice UNEP. Este estudo suporta a hipótese de que o processo de savanização da floresta tropical da Amazônia pode ser acelerado no futuro devido ao aquecimento global, como mostrado nos experimentos AQ+DMT e FUT. Também foi mostrada a praticidade do uso da metodologia para gerar pseudo-cenários de mudança climática com um RCM na América do Sul.
The effects of global warming and future deforestation on c1imate and the biomes distribution over South America using a regional climate model (RCM) were investigated. For this purpose the RegCM4 was driven by ERA-Interim reanalysis for the period 1989-1999 (11-year runs), the control (CTRL) simulation. A methodology for generating surrogate climate-change scenarios with RCM was employed. Three sensibility experiments were performed: 1) global warming (AQ); 2) deforestation (DMT) and 3) deforestation together with global warming (AQ+DMT). For comparison the RegCM4 was integrated using AOGCM ECHAM5/MPI-OM for the present c1imate (1989-1999) (RF) and under A1B SRES scenario (2089-2099) (FUT). To identify the biomes distribution, the Budyko radiative dryness index and the UNEP aridity index were used. The results showed that the simulations of the present climate in both CTRL and RF were in agreement with the observations. The distribution of biomes showed some similarities and differences using the Budyko and UNEP indices. In general the model reproduced the biomes distribution compared with observations. The CTRL simulated better the biomes distribution than RF. The simulations for a surrogate climate (AQ and FUT experiments) were in agreement with other studies of future climate change with RCM and AOGCM which indicated future warming, rainfall increases in southeastern South America, Ecuador and Peru and decreases in the central and eastern Amazon. The distribution of biomes over South America in surrogate climate-change scenario showed an increase of the aridity in the continent using both indices. In the AQ experiment portions of the Amazonia forest were replaced by dry land areas (24,2\% for the UNEP index and 3,4\% for the Budyko index). The semi-arid zone in the northeast of Brazil reached the interior of the north Brazil (21\% of dry land and dry sub-humid regimes may be occupied by areas with semi-arid regime for the UNEP index and 1\% for the Budyko index). The results for the DMT experiment showed that the deforestation may have large influence locally (15\% of the warming when the pseudo warming was inc1uded together). The higher increase of the surface temperature occurred in the south Amazonia (+0.6$°$C) whereas in the north and central Amazonia a decrease of temperature was noted (higher decrease of -0.9$°$C). When the pseudo warming was taken into account together (AQ+DMT) the changes in surface temperature were largely enhanced in relation to the case with only deforestation and the warming occurred in the entire Amazonia (higher increase of +4$°$C). The changes in the distribution of biomes using the Budyko and UNEP indices were in agreement. When the pseudo warming was inc1uded the aridity increased in most of Amazonia compared to the deforestation case. The higher increase of the aridity occurred in the north Amazonia (20\% for the Budyko index and 37.6\% for the UNEP index) while it happened in the south Amazonia in the case of only deforestation (22\% for both the Budyko and UNEP indices). The results showed that although the UNEP and Budyko indices presented potentialities and limitations to represent the biomes distributions for the present climate and surrogate climate scenario the changes in the biomes distribution due to a pseudo-scenario of global warming were higher using the UNEP index. This study corroborates the hypothesis that the process of savannization of the tropical forest of Amazonia can be accelerated in future due to global warming, as found in AQ+ DMT and FUT experiments. Also the feasibility of using the methodology for generating surrogate climate-change scenarios with a RCM for climate change studies in South America was showed.

This thesis examines the EU's influence on regional cooperation in the Association of Southeast Asian Nations (ASEAN), Mercosur in South America and the Southern African Development Community (SADC) by drawing on concepts from diffusion studies. It argues that conventional perspectives have tended to view different cases of regionalism as independent phenomena reflecting particular structural, institutional or ideational conditions, mainly internal to the respective region itself. I propose instead to conceive of regional organisations as asymmetrically interdependent, in that the EU as the most successful regional grouping in the international system influences other regional organisations in important respects; yet in ways that are ill-captured by the conventional depiction of external influence as a form of coercion. The central question addressed in this thesis is thus: Under what conditions and in what ways does the EU affect the trajectory of formal rules in regional cooperation elsewhere? I advance three main arguments. First, I suggest that given the EU's ideational and material power in global regionalism, it is likely to act as a focal point in debates about regional rule change around which actors' expectations converge when being confronted with an exogenous cooperation problem. This renders EU influence difficult to escape. Second, I argue that there are two dynamics by which EU influence affects outcomes in global regionalism - the EU as switchman and as driver. While the former leads policy-makers to choose EU-type rules instead of similarly viable alternatives given a particular cooperation problem, the latter affects the very incentives for regional rule change and thereby acts as an independent driver of regional cooperation. Third, I argue that, in terms of outcomes, EU influence has been highest in SADC, lower in Mercosur and lowest in ASEAN, mainly reflecting different degrees of material and ideational interdependence between the EU and other regions. Yet, policy-makers' widespread reluctance to share national sovereignty has sharply delineated the boundaries of EU influence in all three regions. I test these arguments across three central areas of regional cooperation: market building, institution building and community building.

Modeling groundwater is challenging: it is not readily visible and is difficult to measure, with limited sets of observations available. Even though groundwater models can reproduce water table and head variations, considerable drift in modeled land surface states can nonetheless result from partially known geologic structure, errors in the input forcing fields, and imperfect Land Surface Model (LSM) parameterizations. These models frequently have biased results that are very different from observations. While many hydrologic groups are grappling with developing better models to resolve these issues, it is also possible to make models more robust through data assimilation of observation groundwater data. The goal of this project is to develop a methodology for high-resolution land surface model runs over large spatial region and improve hydrologic modeling through observation data assimilation, and then to apply this methodology to improve groundwater monitoring and banking.

The high-resolution LSM modeling in this dissertation shows that model physics performs well at these resolutions and actually leads to better modeling of water/energy budget terms. The overarching goal of assimilation methodology is to resolve the critical issue of how to improve groundwater modeling in LSMs that lack sub-surface parameterizations and also run them on global scales. To achieve this, the research in this dissertation has been divided into three parts. The first goal was to run a commonly used land surface model at hyper resolution (1 km or finer) and show that this improves the modeling results without breaking the model. The second goal was to develop an observation data assimilation methodology to improve the high-resolution model. The third was to show real-world applications of this methodology.

The need for improved accuracy is currently driving the development of hyper-resolution land surface models that can be implemented at a continental scale with resolutions of 1 km or finer. In Chapter 2, I describe our research incorporating fine-scale grid resolutions and surface data into the National Center for Atmospheric Research (NCAR) Community Land Model (CLM v4.0) for simulations at 1 km, 25 km, and 100 km resolution using 1 km soil and topographic information. Multi-year model runs were performed over the southwestern United States, including the entire state of California and the Colorado River basin. Results show changes in the total amount of CLM-modeled water storage and in the spatial and temporal distributions of water in snow and soil reservoirs, as well as in surface fluxes and energy balance. We also demonstrate the critical scales at which important hydrological processes—such as snow water equivalent, soil moisture content, and runoff—begin to more accurately capture the magnitude of the land water balance for the entire domain. This proves that grid resolution itself is also a critical component of accurate model simulations, and of hydrologic budget closure. (Abstract shortened by UMI.)

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This research is mainly aimed to assess from a multidimensional perspective that considers varying political, social, economic and technological integration of the stages of the Southern Common Market (MERCOSUR) in 1998 and 2008. The theoretical framework includes topics of the theory of regional economic integration; historical process of economic integration in Latin America; history of the formation process of MERCOSUR and its current situation. The methodology used was the Global Dimension of Regional Integration Model considering a total of 90 variables with 18 political, 16 social, 46 economic and technological 10. For each of the States Parties and Associates were calculated Global Regional Development Index and Regional Global Development, and through them we obtained the value for the Regional Integration Stage Index to the MERCOSUR, which is equal to 0.57037 in 1998 and 0.62222 in 2008, framing it as an integration process in development. Analyzing the indexes for each of the States Parties and Associates notes to uneven development between 1998 and 2008 Brazil showed a more than proportional growth in relation to other countries in all areas surveyed. The conclusion is that although the bloc's integration has improved, the effects obtained were not distributed equally among the countries given their heterogeneity.
Este trabalho tem como objetivo central avaliar a partir de uma perspectiva multidimensional que considera variáveis políticas, sociais, econômicas e tecnológicas, os estágios da integração do Mercado Comum do Sul (MERCOSUL) nos anos de 1998 e 2008. O referencial teórico compreende tópicos sobre a teoria da integração econômica regional; processo histórico da integração econômica na América Latina; histórico do processo de formação do MERCOSUL e sua situação atual. A metodologia utilizada foi o Modelo da Dimensão Global da Integração Regional considerando um total de 90 variáveis sendo 18 políticas, 16 sociais, 46 econômicas e 10 tecnológicas. Para cada um dos Estados Partes e Associados foram calculados o Índice Global de Desenvolvimento Regional e o Índice de Desenvolvimento Global Regional e, através destes obteve-se o valor referente ao Estágio de Integração Regional para o MERCOSUL, sendo este igual a 0,57037 em 1998 e a 0,62222 em 2008, enquadrando o mesmo como um processo integracionista em desenvolvimento. Analisando os índices para cada um dos Estados Partes e Associados constata-se um desenvolvimento desigual entre 1998 e 2008 apresentando o Brasil um crescimento mais que proporcional em relação aos demais países em todas as áreas analisadas. Conclui-se que embora a integração do bloco tenha apresentado avanços, os efeitos obtidos não se distribuíram de forma igualitária entre os países dada sua heterogeneidade.

Marine sediments are a key component of the global carbon cycle and climate system. They host one of the largest carbon reservoirs on Earth, provide the only long-term sink for atmospheric CO2, recycle nutrients and represent the most important climate archive. Early diagenetic pro- cesses in marine sediments are thus central to our understanding of past, present and future biogeochemical cycling and climate. Because all early diagenetic processes can be directly or indirectly linked back to the degradation of organic matter (OM), advancing this understand- ing requires disentangling the different factors that control the fate of OM (sedimentation, degradation and burial) on different spatial and temporal scales. In general, the heterotrophic degradation of OM in marine sediments is controlled by the quantity and, in particular, by the ap- parent reactivity of OM that settles onto marine sediments. While the potential ((micro)biological, chemical and physical) controls on OM reactivity are increasingly well understood, their relative significance remains difficult to quantify. Traditionally, integrated data-model approaches are used to quantify apparent OM reactivity (i.e. OM degradation rate constants) at well-studied drill-sites. These approaches rely on Reaction-Transport Models (RTMs) that typically account for transport (advection, molecular diffusion, bioturbation, and bioirrigation) and reaction (pro- duction, consumption, equilibrium) processes, but vary in complexity. Apparent OM reactivity (i.e. the OM degradation rate constant) is generally considered as a free parameter that is used to fit observed depth-profiles, reaction rates or benthic-pelagic exchange fluxes. Currently, no quantitative framework exists to predict apparent OM reactivity in areas where comprehensive benthic data sets are not available.To evaluate the impact of this knowledge gap, the sensitivity of benthic biogeochemical reaction rates, as well as benthic-pelagic exchange fluxes to variations in apparent OM reactivity (i.e. reactive continuum model parameters a and ν) is explored by means of a complex, numerical diagenetic model for shelf, slope and deep sea depositional environments. Model results show that apparent OM reactivity exerts a dominant control on the magnitude of biogeochemical reaction rates and benthic-pelagic exchange fluxes across different environments. The lack of a general framework to quantify OM reactivity thus complicates the parametrization of regional and global scale diagenetic models and, thus, compromises our ability to quantify global benthic-pelagic coupling in general and OM degradation dynamics in particular.To make a first step towards an improved systematic and quantitative knowledge of OM reac- tivity, apparent OM reactivity (i.e. reactive continuum model parameters a and ν) is quantified by inverse modelling of organic carbon, sulfate (and methane) sediment profiles, as well as the location of the sulfate-methane transition zone using a complex, numerical diagenetic model for 14 individual sites across different depositional environments. Model results highlight again the dominant control of OM reactivity on biogeochemical reaction rates and benthic exchange fluxes. In addition, results show that, inversely determined ν-values fall within a narrow range (0.1 < ν < 0.2). In contrast, determined a-values span ten orders of magnitude (1 · 10−3 < a < 1·107) and are, thus, the main driver of the global variability in OM reactivity. Exploring these trends in their environmental context reveals that apparent OM reactivity is determined by a dynamic set of environmental controls rather than traditionally proposed single environmental controls (e.g. water depth, sedimentation rate, OM fluxes). However, the high computational demand associated with such a multi-species inverse model approach, as well as the limited availability of comprehensive pore water data, limits the number of apparent OM reactivity estimates. Therefore, while providing important primers for a quantification of OM reactivity on the global scale, inverse model results fall short of providing a predictive framework.To overcome the computational limitations and expand the inverse modelling of apparent OM reactivity to the global scale, the analytical model OMEN-SED is extended by integrating a nG- approximation of the reactive continuum model that is fully consistent with the general structure of OMEN-SED. The new version OMEN-SED-RCM thus provides the computational efficiency required for the inverse determination of apparent OM reactivity (i.e. reactive continuum model parameters a and ν) on the global scale. The abilities of the new model OMEN-SED-RCM in capturing observed local, as well as global patterns of diagenetic dynamics are rigorously tested by model-data, as well as model-model comparison.OMEN-SED-RCM is then used to inversely determine apparent OM reactivity by inverse modelling of 394 individual dissolved oxygen utilisation (DOU) rate measurements. DOU is commonly used as a proxy for OM reactivity, it is more widely available than comprehensive porewater data sets and global/regional benthic maps of dissolved oxygen utilisation rates (DOU) have been derived based on the growing DOU data set. Sensitivity test show that, while inverse modelling of DOU rates fails to provide a robust estimate of RCM parameter ν, it is a good indicator for RCM parameter a. Based on previous findings, parameter ν was thus assumed to be globally constant. Inversely determined a-values vary over order of magnitudes from a = 0.6 years in the South Polar region to a = 5.6 · 106 in the oligotrophic, central South Pacific. Despite a high intra- as well as interregional heterogeneity in apparent benthic OM reactivity, a number of clear regional patterns that broadly agree with previous observations emerge. High apparent OM reactivities are generally observed in regions dominated by marine OM sources and characterized by efficient sinking of OM and a limited degradation during sinking. In contrast, the lowest apparent OM reactivities are observed for regions characterized by low marine primary production rates, in combination with a great distance to the continental shelf and slope, as well as deep water columns. Yet, results also highlight the importance of lateral transport processes for apparent OM reactivity. In particular, deep sea sediments in the vicinity of dynamic continental margin environments or under the influence of strong ocean currents can receive comparably reactive OM inputs from more productive environments and, thus, reveal OM reactivities that are higher than traditionally expected. Finally, based on the observed strong link between apparent OM reactivity (i.e. RCM parameters a) and DOU rate, a transfer function that predicts the order of magnitude of RCM parameter a as a function of DOU is used to derive, to our knowledge, the first global map of apparent OM reactivity.Finally, we use the new global map of apparent OM reactivity to quantify biogeochemical dynamics and benthic-pelagic coupling across 22 benthic provinces that cover the entire global ocean. To this end, the numerical diagenetic model BRNS model is set-up for each province and forced with regionally averaged boundary conditions derived from global data sets, as well as apparent OM reactivities informed by the global OM reactivity map. The 22 regional model set-ups were then used to quantify biogeochemical process rates, as well as benthic carbon and nutrient fluxes in each province and on the global scale. Model results of regional and global fluxes and rates fall well within the range of observed values and also agree with general globally observed patterns. Results also highlight the role of the deeper ocean for benthic-pelagic cycling and indicate towards a large regional variability in benthic cycling at great depth. This is a first step towards a more refined global estimate of benthic biogeochemical cycling that accounts for the global heterogeneity of the seafloor environment. This aspect is critical to improve our understanding of benthic feedbacks on benthic-pelagic coupling and on the carbon-climate system, which can then be incorporated in benthic processes in Earth System Models.
Les sédiments marins sont un élément clé du cycle mondial du carbone et du système climatique. Ils abritent l’un des plus grands réservoirs de carbone sur Terre, fournissent le seul puits à long terme pour le CO2 atmosphérique, recyclent les nutriments et constituent les archives climatiques les plus importantes. Les processus de la diagénèse précoce dans les sédiments marins sont donc au cœur de notre compréhension des cycles et du climat biogéochimiques passés, présents et futurs. Étant donné que tous les processus diagénétiques précoces peuvent être directement ou indirectement liés à la dégradation de la matière organique (MO), faire progresser cette compréhension nécessite de démêler les différents facteurs qui contrôlent le devenir de la MO (sédimentation, dégradation et enfouissement) à différentes échelles spatiales et temporelles. En général, la dégradation hétérotrophique de la MO dans les sédiments marins est contrôlée par la quantité et, en particulier, la réactivité apparente de la MO qui se dépose sur les sédiments marins. Bien que les contrôles potentiels ((micro) biologiques, chimiques et physiques) de la réactivité de la MO soient de mieux en mieux compris, leur importance relative reste difficile à quantifier. Traditionnellement, des approches de modèle de données intégrées sont utilisées pour quantifier la réactivité apparente de la MO (c’est-à-dire les constantes de vitesse de dégradation de la MO) sur des sites de forage bien étudiés. Ces approches reposent sur des modèles de réaction-transport (RTM) qui tiennent généralement compte des processus de transport (advection, diffusion moléculaire, bioturbation et bio-irrigation) et de réaction (production, consommation, équilibre), mais leur complexité varie. La réactivité apparente de la MO est généralement considérée comme un paramètre libre qui est utilisé pour ajuster les profils de profondeur, les taux de réaction ou les flux d’échange benthique-pélagique observés. À l’heure actuelle, aucun cadre quantitatif n’existe pour prédire la réactivité apparente de la MO dans les zones où aucun ensemble complet de données benthiques n’est disponible.Pour évaluer l’impact de ce manque de connaissance, nous avons exploré la sensibilité des taux de réaction biogéochimiques benthiques, ainsi que des flux d’échange benthique-pélagique aux variations de la réactivité apparente de la MO (c.-à-d. les paramètres du modèle de con- tinuum réactif a et ν) au moyen d’un modèle diagénétique numérique complexe appliqué aux zones de dépôts sur les plateaux, les talus et en haute mer. Les résultats du modèle montrent que la réactivité apparente de la MO exerce un contrôle dominant sur l’ampleur des taux de réaction biogéochimiques et des flux d’échange benthique-pélagique dans différents environ- nements. L’absence d’un cadre général pour quantifier la réactivité de la MO complique donc la paramétrisation des modèles diagénétiques à l’échelle régionale et mondiale et, ainsi, compromet notre capacité à quantifier le couplage benthique-pélagique global en général et la dynamique de dégradation de la MO en particulier.Pour tendre à meilleure connaissance systématique et quantitative de la réactivité de la MO, la réactivité apparente OM (c.-à-d. les paramètres du modèle de continuum réactif a et ν) est quantifiée par modélisation inverse des profils de sédiments organiques de carbone, de sulfate (et de méthane), ainsi que localisation de la zone de transition sulfate-méthane à l’aide d’un modèle diagénétique numérique complexe pour 14 sites individuels à travers différents environnements de dépôt. Les résultats du modèle mettent à nouveau en évidence le contrôle dominant de la réactivité de l’OM sur les taux de réaction biogéochimiques et les flux d’échanges benthiques. De plus, les résultats montrent que les valeurs déterminées inversement déterminées se situent dans une plage étroite (0,1 <ν<0,2). En revanche, les valeurs déterminées s’étendent sur dix ordres de grandeur (1 ·10−3 <ν< 1·107) et sont donc le principal moteur de la variabilité globale de la réactivité OM. L’exploration de ces tendances dans leur contexte environnemental révèle que la réactivité apparente de l’OM est déterminée par un ensemble dynamique de contrôles environnementaux plutôt que par des contrôles environnementaux uniques traditionnellement proposés (par exemple, la profondeur de l’eau, le taux de sédimentation, les flux OM). Cependant, la forte demande de calcul associée à une telle approche de modèle inverse multi-espèces, ainsi que la disponibilité limitée de données complètes sur l’eau interstitielle, limitent le nombre d’estimations apparentes de la réactivité OM. Par conséquent, tout en fournissant des amorces importantes pour une quantification de la réactivité de l’OM à l’échelle mondiale, les résultats du modèle inverse sont loin de fournir un cadre prédictif.Pour surmonter les limites de calcul et étendre la modélisation inverse de la réactivité apparente de l’OM à l’échelle mondiale, le modèle analytique OMEN-SED est étendu en intégrant une approximation nG du modèle de continuum réactif qui est pleinement cohérente avec la structure générale d’OMEN-SED. La nouvelle version OMEN-SED-RCM fournit ainsi l’efficacité de calcul requise pour la détermination inverse de la réactivité apparente de l’OM (c’est-à-dire les paramètres du modèle de continuum réactif a et ν) à l’échelle mondiale. Les capacités du nouveau modèle OMEN-SED-RCM à capturer les modèles locaux et globaux de dynamique diagénétique observés sont rigoureusement testés par les données du modèle, ainsi que la comparaison modèle- modèle.OMEN-SED-RCM est ensuite utilisé pour déterminer inversement la réactivité apparente de l’OM par modélisation inverse de 394 mesures individuelles du taux d’utilisation de l’oxygène dissous (DOU). Le DOU est couramment utilisé comme indicateur de la réactivité de l’OM, il est plus largement disponible que les ensembles de données exhaustifs sur l’eau interstitielle et les cartes benthiques mondiales/régionales des taux d’utilisation de l’oxygène dissous (DOU) ont été dérivées sur la base de l’ensemble de données DOU croissant. Le test de sensibilité montre que, bien que la modélisation inverse des taux de DOU ne fournisse pas une estimation robuste du paramètre RCM ν, c’est un bon indicateur pour le paramètre RCM a. Sur la base des résultats précédents, le paramètre ν a donc été supposé être globalement constant. Les valeurs a déterminées à l’inverse varient selon l’ordre de grandeur, de a = 0,6 an dans la région polaire sud à a = 5, 6 · 106 dans le Pacifique sud oligotrophique central. Malgré une forte hétérogénéité intra et interrégionale dans la réactivité apparente de la MO benthique, un certain nombre de schémas régionaux clairs qui correspondent largement aux observations précédentes émergent. Des réactivités apparentes élevées de l’OM sont généralement observées dans les régions dominées par des sources marines de MO et caractérisées par un naufrage efficace de l’OM et une dégradation limitée pendant le naufrage. En revanche, les réactivités MO apparentes les plus faibles sont observées pour les régions caractérisées par de faibles taux de production primaire marine, en combinaison avec une grande distance du plateau continental et de la pente, ainsi que des colonnes d’eau profonde. Pourtant, les résultats mettent également en évidence l’importance des processus de transport latéral pour la réactivité apparente de l’OM.En particulier, les sédiments des mers profondes au voisinage d’environnements de marge continentale dynamiques ou sous l’influence de forts courants océaniques peuvent recevoir des apports OM de réactivité comparable provenant d’environnements plus productifs et, ainsi, révéler des réactivités OM plus élevées que ce qui était traditionnellement prévu. Enfin, sur la base du lien fort observé entre la réactivité apparente de l’OM (c’est-à-dire le paramètre RCM a) et le taux DOU, une fonction de transfert qui prédit l’ordre de grandeur du paramètre RCM a en fonction de DOU est utilisée pour dériver, pour nos connaissances, la première carte mondiale de la réactivité apparente de l’OM. Les résultats du modèle des flux et des taux régionaux et mondiaux se situent bien dans la gamme des valeurs observées et également d’accord avec les tendances générales observées au niveau mondial. Les résultats mettent également en évidence le rôle de l’océan profond pour le cycle benthique-pélagique et indiquent une grande variabilité régionale du cycle benthique à grande profondeur. Il s’agit d’une première étape vers une estimation mondiale plus précise du cycle biogéochimique benthique qui tient compte de l’hétérogénéité mondiale du milieu marin. Cet aspect est essentiel pour améliorer notre compréhension des rétroactions benthiques sur le couplage benthique-pélagique et sur le système carbone-climat, qui peuvent ensuite être incorporées aux processus benthiques dans les modèles du système terrestre.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

At a meeting of worl leaders at the United Nations Conference on Environment and Development in Rio de Janeiro in 1992, it was recognized that because of the tremendous increase in the size of the global populations (which now is estimated to exceed six billion), there were concerns that global biodiversity was at risk if insufficient land were not put aside for conservation within formal Protected Areas. The primary aim of this study was to compare investment in Protected Areas in relation to socio-economic conditions at global and regional levels.

This paper explores the relationship between household income inequality and macroeconomic uncertainty in the United States. Using a novel large-scale macroeconometric model, we shed light on regional disparities of inequality responses to a national uncertainty shock. The results suggest that income inequality decreases in most states, with a pronounced degree of heterogeneity in terms of the dynamic responses. By contrast, some few states, mostly located in the Midwest, display increasing levels of income inequality over time. Forecast error variance and historical decompositions highlight the importance of uncertainty shocks in explaining income inequality in most regions considered. Finally, we explain differences in the responses of income inequality by means of a simple regression analysis. These regressions reveal that the income composition as well as labor market fundamentals determine the directional pattern of the dynamic responses.
Series: Working Papers in Regional Science

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This study objective was to analyze the space distribution of components of the reference evapotranspiration (ETo) in Brazil and afterwards the weather variability by applying the technique of harmonic analysis, given for this was initially an analysis of variance, phase and amplitude for the present time (1980-2000), subsequently made a projection of future time (2080-2100), based on scenario A2 of intergovernmental panel to Climatic changes. The equation used was Penman-Monteith sampled by Food and Agriculture and Organization of the United Nations (FAO) 1998. The simulations were conducted with the clime regional model (MM5), attached to a model of potential vegetation (MVP). The results show that under the actual conditions the model presented good performance of the annual cycle when compared to the ERA-40 and CRU data. The aero dynamical and radioactive terms presented an annual cycle that is dominant in the Amazonian and Brazil's south regions, while in the southeast region the semester cycle has a higher notability. The biggest variations at ETo amplitude were identified in northeastern semiarid and in the Brazil's extreme south. The changes in ETo due to the global warmness were maximum at the Brazil's central region and in the Amazonian region. In future conditions, the annual cycle showed itself dominant in Brazil's greatest part, presenting dry and rainy well defined weathers. Still was observed that under global warmness conditions the variations of aerodynamic term become more important than the variations of the irradiative terms to the total ETo.
O objetivo do presente estudo foi analisar a distribuição espacial dos componentes da evapotranspiração de referência (ETo) no Brasil e posteriormente a variabilidade temporal por meio da técnica da análise harmônica, sendo para isso foi feito inicialmente uma análise de variância, fase e amplitude para o tempo presente (1980-2000) e, posteriormente, feita uma projeção com o tempo futuro (2080-2100), com base no cenário A2 do Painel Intergovernamental para as Mudanças Climáticas. A equação utilizada foi a de Penman-Monteith padronizada pela Food and Agriculture and Organization of the United Nations (FAO) 1998. As simulações foram conduzidas com o modelo regional de clima (MM5), acoplado a um modelo de vegetação potencial (MVP). Os resultados mostram que sob condições atuais o modelo apresentou bom desempenho do ciclo anual quando comparado aos dados do ERA-40 e CRU. Os termos aerodinâmico e radiativo apresentaram um ciclo anual que é dominante na região Amazônica e sul do Brasil, enquanto na região sudeste o ciclo semestral tem maior destaque. As maiores variações na amplitude da ETo foram identificadas no semi-árido nordestino e no extremo sul do Brasil. As mudanças na ETo devido ao aquecimento global foram máximas na região central do Brasil e Amazônica. Em condições futuras, o ciclo anual apresentou-se dominante na maior parte do Brasil, indicando estações secas e chuvosas de forma bem definida. Ainda foi observado que sob condições de aquecimento global as variações do termo aerodinâmico tornam-se mais importantes que as variações do termo radiativo para a ETo total.

Air pollution is a serious issue that affects human health, the environment and the climate at levels from local to global scales. The main processes that affect air pollution levels are: emissions, chemistry, transport and deposition. Air quality models (AQMs) are mathematical tools that describe relevant physicochemical processes and quantify concentrations of air pollutants. Therefore, AQMs can be used to develop and detail measures taken to reduce air quality problems. Several AQMs are currently used and they have undergone a rapid evolution in recent years. Computer capacity has increased during the last decade enabling us to use higher spatial resolutions and more complex parameterizations schemes that resolve more complex atmospheric processes. Moreover, previous research has shown that the feedbacks between meteorology and chemistry are important in the context of many research applications. Therefore, this increase in computing power allows accurately simulate those feedbacks (online modelling). Online models are becoming more used in the atmospheric community. The NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM) is being developed through an ongoing team effort at the Earth Sciences Department of the Barcelona Supercomputing Center (BSC). The main motivation for this thesis is to contribute in the development of a unified fully coupled chemical weather prediction system able to solve gas-aerosol-meteorology interactions within a wide range of scales on local to global domains that can be used in both operational and research applications. In this sense, the focus in this Ph.D. has been on the development and evaluation of the tropospheric gas-phase chemistry within the online Global / Regional atmospheric model NMMB/BSC-CTM. With the meteorological core NMMB as the starting point, different parameterizations of several atmospheric chemistry processes such as dry deposition, photolysis, wet deposition, gas-phase chemistry, and stratospheric ozone handling have been reviewed, implemented and evaluated during this Ph.D. thesis. A complete spatial, temporal and vertical model evaluation of the relevant chemical species using different observational data has been performed in this Ph.D. thesis. Observational data has included ground-monitoring stations, ozonesondes, satellite data, climatologies and, aircraft campaigns. This is the first time that the gas-phase chemistry of the NMMB/BSC-CTM has been evaluated on a regional and global scales over a full year. Concerning the model evaluation in the regional scale, we had the opportunity to participate in the Air Quality Model Evaluation International Initiative (AQMEII) Phase2 which aims to intercompare online coupled regional-scale models over North America and Europe. In this sense, we were participating in this initiative in the European runs with NMMB/BSC-CTM model. The model evaluations have shown a good agreement with observations. Overall, the model performance corresponds to state-of-the-art regional and global AQMs.
La contaminació de l’aire és un problema greu que afecta la salut humana i el medi ambient, tant a escala local com global. Els principals processos que concerneixen els nivells de contaminació de l’aire són les emissions, la química, el transport i la deposició. Els Models de Qualitat de l’Aire (AQMS) són eines matemàtiques que descriuen aquests processos fisicoquímics i quantifiquen les concentracions de contaminants de l’aire. Per tant, els AQMS es poden utilitzar per desenvolupar i detallar les mesures preses per reduir la mala qualitat de l’aire. Actualment, es fan servir diversos AQMS i aquests darrers anys han evolucionat molt ràpidament. La capacitat de la computació ha augmentat durant l’última dècada, i això ha fet possible una resolució espacial més bona i uns esquemes de parametritzacions més complexos que resolen més processos atmosfèrics. D’una altra banda, la investigació ha demostrat que els feedbacks entre la meteorologia i la química són certament importants en moltes aplicacions de recerca. Per tant, l’augment de la potència de càlcul permet simular acuradament aquests feedbacks (modelizació online). Els models online són cada vegada més utilitzats en la comunitat atmosfèrica. El NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM) es desenvolupa gràcies a un esforç d’equip al Departament de Ciències de la Terra del Barcelona Supercomputing Center (BSC). La principal motivació d’aquesta tesi és contribuir al desenvolupament i a l’avaluació d’un sistema de predicció unificat que sigui capaç de resoldre les interaccions gas-aerosolmeteorologia dins un ampli rang d’escales, des de dominis locals a globals, i que pugui ser utilitzat tant en aplicacions operatives com d’investigació. En aquest sentit, el principal objectiu d’aquesta tesi doctoral és el desenvolupament i l’avaluació de la química troposfèrica en fase gasosa del model online global/regional NMMB/BSC-CTM. Utilitzant el nucli meteorològic NMMB com a punt de partida, diverses parametritzacions de processos químics atmosfèrics com ara la deposició seca, la fotòlisi, la química dels núvol, la química en fase gasosa i l’intercanvi d’ozó entre estratosfera i troposfera han estat revisats, implementats i avaluats durant aquesta tesi doctoral. S’ha dut a terme una avaluació completa a nivell espacial, temporal i vertical de les espècies químiques més rellevants mitjançant diverses observacions a escala global i regional. Aquestes observacions inclouen estacions a nivell de superfície, ozonosondes, dades de satèl.lit, climatologies i campanyes d’aeronaus. És la primera vegada que la química en fase gasosa de l’NMMB/BSC-CTM s’avalua a escala global i regional durant un any complet. Respecte l’evaluació del model a nivell regional, vam tenir l’oportunitat de participar en el projecte de l’Air Quality Model Evaluation International Initiative (AQMEII) Phase2. L’objectiu principal d’aquest projecte és la intercomparació de models online a escala regional sobre l’Amèrica del Nord i Europa. El nostre grup va participar en aquesta iniciativa sobre el domini europeu utilitzant el model NMMB/BSC-CTM. L’avaluació del model mostra una bona avinença amb les observacions. En general, els resultats del model es corresponen amb l’estat de l’art dels AQMS a escala regional i global.

Many studies on forest or vegetation response to global warming have been done using the gap model or empirical models. Thus far, there is no good regional model allowing to predict forest change at an intermediate scale. In this study, we have developed a model of this type, called Knowledge Base Forest Model (KBFM), using an information analytical tool (P scEGASE) based on information theory. Using this model and data from the Canadian Climatic Centre general circulation model, we could predict the future distribution of forest types in the research area: the Province of Manitoba. The study shows that the KBFM may well be used to predict the future regional distribution of forest types. Its main advantages are: (1) environmental variables used as predictors can be qualitatives (e.g. soil texture) as well as quantitative (e.g. temperature); (2) the KBFM provides the possibility to account for the role of soil factors in the forest response to global warming; (3) the KBFM can predict forest type distribution using various climatic scenarios; (4) the KBFM can predict forest type distribution with greater details than empirical models.

Les variations du rayonnement solaire en surface (SSR) peuvent avoir un impact significatif sur divers aspects du système climatique, et notamment sur le développement socio-économique d’un pays. Pour identifier les impacts possibles du changement climatique sur le rayonnement solaire en surface à l'échelle régionale (~ 50 km) en Afrique australe jusqu'à la fin du 21ème siècle, on a analysé les données mensuelles produites dans le cadre du projet CORDEX-Afrique sur la période 1979-2099. Ces données sont issues des sorties de 5 modèles régionaux de climat (RCM) forcés par 10 modèles globaux de climat (GCM) CMIP5, pour deux scénarios d’émissions, RCP4.5 et RCP8.5, en Afrique australe (SA) et sur une partie du SWIO (0-40°S ; 0- 60°E). Pour contribuer au projet futur proposé qui vise à approfondir l'étude des changements de SSR à l'échelle locale (~ 1 km de résolution horizontale) à l'île de la Réunion et à l'île Maurice, situées dans le Sud-ouest de l'océan Indien (SWIO), près du bord d’Est du domaine CORDEX-Afrique, des simulations climatiques ont été réalisées sur trois fenêtres temporelles de 10 ans : a) le passé 1996-2005 ; et b) le futur 2046-2055 et 2090-2099, en utilisant la version 4 du RCM RegCM (RegCM4), forcé par : 1) les réanalyses climatiques ERA-Interim (ERAINT) du centre européen pour les prévisions météorologiques à moyen terme (ECMWF) pour simuler un passé récent seulement ; et 2) deux GCMs (HadGEM2-ES et GFDL-ESM2M) de l’exercice CMIP5 de simulations du climat passé et futur pour le scénario d’émissions RCP8.5 à l’échelle régionale de 50km en Afrique australe et dans le sud-ouest de l’océan Indien (0-40°S ; 0- 100°E). L’analyse de l’impact du changement climatique sur le SSR sur la base de ces simulations reste cependant limitée, à cause de leur couverture temporelle (3 périodes de 10 ans) et du nombre de modèles (2 GCMs, 1 RCM) et de scénarios (1 RCP) utilisés. Il ressort de l’analyse des simulations de l’ensemble CORDEX-Afrique que : 1) sur la période passée récente, les GCMs forceurs surestiment généralement SSR d'environ 1 W/m2 en été austral (DJF : Décembre-Janvier-Février), et de 7,5 W/m2 en hiver austral (JJA : Juin-Juillet-Août), tandis que les RCMs, forcés par ces GCMs, sous-estiment SSR d'environ -32 W/m2 et de -14 W/m2 en été et en hiver, respectivement. 2) Les projections multi-modèles de changement de SSR simulées par les RCMs et leurs GCMs forceurs sont assez cohérentes. Les GCMs prévoient, en moyenne multi-modèles, une augmentation statistiquement significative de SSR d'environ 8 W/m2 en 2099 selon le scénario RCP4.5 et de 12 W/m2 en 2099 selon le scénario RCP8.5 sur le Centre de l’Afrique australe (SA-C), et une diminution de SSR, avec un degré de confiance élevé, d'environ -5 W/m2 en 2099 selon le scénario RCP4.5 et de -10 W/m2 en 2099 selon le scénario RCP8.5, pendant la saison DJF, en Afrique équatoriale (EA-E). Dans ces deux régions, les RCMs produisent, en moyenne multi-modèles, des tendances similaires (avec un degré de confiance élevé) à celles des GCMs, mais sur des zones d’extension spatiale plus faible que celle des GCMs. Cependant, pour la saison JJA, une augmentation de SSR, d'amplitude similaire dans les simulations GCMs et RCMs (~5 W/m2 en 2099 selon le scénario RCP4.5 et 10 W/m2 selon le scénario RCP8.5), est attendue dans la région EA-E. 3). Une diminution significative de la nébulosité (environ -6% en 2099) est attendue sur le continent sud-africain pour les GCMs comme pour les RCMs. 4) Le scénario RCP8.5 produit des changements d’amplitude supérieure de 2.5W/m2 pour les GCMs forceurs et de 5W/m2 pour les RCMs en 2099 à celle pour le scénario RCP4.5. 5). Comme pour les sorties du modèle RegCM4, les structures des biais ou des changements de SSR issu des RCMs du programme CORDEX-Afrique sont globalement corrélées avec celles de couverture nuageuse totale des RCMs. L’analyse des sorties du modèle RegCM4 indique que :
Changes in Surface Solar Radiation (SSR) have the potential to significantly impact diverse aspects of the climate system, and notably the socio-economic development of any nation. To identify the possible impacts of climate change on SSR at regional scales (~50 km) over Southern Africa and the South West Indian Ocean (SA-SWIO; 0-40°S ; 0- 100°E) up to the end of the 21st century, a slice downscaling experiment consisting of simulations covering three temporal windows: a) the present 1996-2005; b) the future 2046-2055 and 2090-2099 conducted with the Regional Climate Model (RCM) RegCM version 4, driven by the European Center for Medium-range Weather Forecasting (ECMWF) ERA-Interim reanalysis (ERAINT, only present) and 2 Global Climate Model (GCMs: HadGEM2-ES and GFDL-ESM2M) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under RCP8.5 scenario, are performed and evaluated. Since the slice simulation is of limited temporal coverage, number of regional and driven global models and climate change forcings, mainly because of the limit of available computational resources, the study towards a comprehensive knowledge of SSR changes in context of climate change is thus extended: an ensemble consisting of outputs from 20 regional climate downscaling realisations based on 5 RCMs that participated in the Coordinated Regional Downscaling Experiment (CORDEX) program (CORDEX-Africa) along with their 10 driving GCMs from CMIP5 covering southern Africa (0-40°S; 0- 100°E) during the period of 1990-2099 is analyzed under RCP4.5 and RCP8.5 up to 2099.The slice experiment indicates that 1) RegCM4 simulates present-day seasonal climatology, (surface air temperature, precipitation and SSR) quite well, but has a negative total cloud cover bias (about -20% in absolute percentage) when forced by the ERAINT and the two GCMs. 2) Internal variability of RegCM4-simulated annual means SSR (about 0.2 W/m2) is of one order smaller than the model bias compared with reference data. 3) RegCM4 simulates SSR changes in opposite signs when driven by the different GCMs under RCP8.5 scenario. 4) Electricity potential calculated using first-order estimation based on the RegCM simulations indicates a change less then 2% to 2099 with respect on present level.It is also found from the ensemble study that: 1) GCMs ensemble generally overestimates SSR by about 1 W/m2 in austral summer (December, January, and February, short as DJF) and 7.5 W/m2 in austral winter (June, July and August, short as JJA), while RCMs ensemble mean shows underestimations of SSR by about -32 W/m2 and -14 W/m2 in summer and winter seasons respectively when driven by GCMs. 2) Multi-model mean projections of SSR change patterns simulated by the GCMs and their embedded RCMs are fairly consistent. 3) GCMs project, in their multi-model means, a statistically significant increase of SSR of about 8 W/m2 in RCP4.5 and 12 W/m2 in RCP8.5 by 2099 over Centre Southern Africa (SA-C) and a highly confident decreasing SSR over Eastern Equatorial Africa (EA-E) of about -5 W/m2 in RCP4.5 and -10 W/m2 in RCP8.5 during the DJF season. RCMs simulate SSR change with statistical confidence over SA-C and EA-E area as well with a little spatial extension compared to GCMs. However, in the JJA season, an increase of SSR is found over EA-E of about 5 W/m2 by 2099 under RCP4.5 and 10 W/m2 under RCP8.5, of similar amplitudes in both the GCMs and RCMs simulations. 4) Significant cloudiness decrease (about -6 % to 2099) is found over continent of SA for GCMs and also shown in RCMs. 5) Larger SSR changes are found in the RCP8.5 scenario than in the RCP4.5 scenario in 2099, with about 2.5 W/m2 enhanced changes in GCMs and about 5 W/m2 in RCMs. 6) Either the biases or the changes pattern of SSR are overall correlated with the patterns of total cloud cover from RCMs in CORDEX-Africa program (for RegCM4 as well). The slice experiment indicates that

En Europe, l'augmentation des températures moyennes de surface de l'air projetée au cours du 21ème siècle s'accompagne d'une augmentation des extrêmes chauds et d'une diminution des extrêmes froids. Dans les dernières décennies, des indices témoignent déjà de ces changements, comme l'établissement récurrent de nouveaux records de chaleur ou l'augmentation des canicules. Nous étudions l'évolution des extrêmes journaliers de température au cours du 20ème et du 21ème siècle en France et en Europe, et ce en termes d'occurrence et d'intensité. Un intérêt particulier est aussi porté aux mécanismes responsables de ces futurs extrêmes climatiques, ainsi qu'aux futures températures maximales. Nous nous intéressons tout d'abord à l'évolution des records journaliers de température à partir d'observations et de modèles de climat. Entre 1950 et 1980, l'évolution théorique des records dans le cadre d'un climat stationnaire représente correctement l'évolution observée des records chauds et froids. Depuis les années 1980, un écart à ce climat stationnaire est observé, avec respectivement une augmentation et une diminution de l'occurrence des records chauds et froids. Les modèles climatiques suggèrent une accentuation de ces changements au cours du siècle. L'occurrence moyenne des records chauds à la fin du siècle présente une forte augmentation par rapport aux premières décennies de la période observée. L'augmentation la plus importante des records chauds est projetée en été, en particulier dans la région méditerranéenne. Quant aux records froids, les modèles indiquent une diminution très importante de leur occurrence, avec une occurrence quasi-nulle dans les dernières décennies. Les variations observées d'occurrence de records sont, au début du 21ème siècle, toujours dans l'éventail des fluctuations de la variabilité interne du climat. Au cours du siècle, l'émergence de l'influence anthropique de ces fluctuations est détectable dans l'évolution des records chauds et froids en été, et ce respectivement autour des décennies 2030 et 2020. À l'horizon de la fin du siècle, les changements moyens d'occurrence de records ne peuvent pas être uniquement expliqués par des fluctuations naturelles. Nous nous sommes ensuite intéressés aux futures températures estivales extrêmes, ainsi qu'aux canicules intenses qui peuvent être à l'origine de ces extrêmes. Pour cela, l'utilisation de modèles climatiques globaux est associée à la modélisation climatique régionale et à des stations d'observations en France. Tout d'abord, l'augmentation maximale des valeurs maximales des records journaliers de température en été en France est estimée à partir d'une simulation régionale à haute résolution spatiale. À l'horizon 2100, les projections indiquent une augmentation maximale de ces valeurs extrêmes en été comprise entre de 6.6°C et 9.9°C selon les régions de la France. La comparaison de ces projections avec un ensemble de modèles climatiques indique que ces augmentations maximales pourraient être plus importantes. La médiane de la distribution des modèles indique en effet une augmentation maximale de ces valeurs maximales des records journaliers de température de 11.8°C en été et en France. Puis, des expériences de modélisation de canicules intenses du climat européen de la fin du 21ème siècle ont été réalisées à partir d'événements particuliers d'un modèle de climat. Ces expériences ont mis en évidence le rôle des interactions entre le sol et l'atmosphère dans l'amplification des températures extrêmes lors de futurs évènements caniculaire intenses. L'occurrence de telles canicules est d'abord dépendante de la circulation atmosphérique, mais l'intensité des températures peut ensuite être fortement amplifiée en fonction du contenu en humidité des sols avant la canicule, et donc des conditions climatiques des semaines et des mois précédents
Over the 21st century, the mean increase in surface air temperatures is projected to be associated with an increase in warm temperature extremes and a decrease in the cold ones. Over the last decades, evidence already suggests these changes, as for example recurrent warm record-breaking temperatures or the increase in heatwave occurrence. We investigate the evolution of daily temperature extremes over the 20th and the 21st centuries in France and in Europe, their possible changes in frequency and intensity. We also focus on the mechanisms responsible for these projected climate extremes, as well as the maximum values of temperature extremes at the end of the century. First, we investigate the evolution of daily record-breaking temperatures in Europe based on the observations and an ensemble of climate models. From the 1950s to the 1980s, the theoretical evolution of the records in a stationary climate correctly reproduce the observed one, for both cold and warm records. From 1980, a shift from that theoretical evolution is observed, with an increase in the occurrence of warm records and a decrease in the occurrence of the cold ones. Climate models suggest an amplification of these changes over the century. At the end of the 21st century, the mean number of warm records shows a strong increase compared to the first decades of the observed period. The strongest increase in warm record-breaking temperatures is found in summer, and particularly over the Mediterranean edge. On the contrary, the occurrence of cold record-breaking temperatures is projected to strongly decrease, with almost no new records in the last decades of the century, for all seasons and over the entire European domain. Observed variations of daily record-breaking temperatures are still, at the beginning of the 21st century, consistent with internal climate variability only. Over the century, the anthropogenic influence emerge from these fluctuations in the summer record evolutions, around the 2030 and the 2020 for the warm and cold records respectively. By 2100, the mean changes in record occurrences cannot be explained by the internal climate variability solely, for all seasons and over the entire European domain. Then, we investigate future extreme temperatures at the end of the 21st century, as well as severe heatwaves leading to these extremes. Climate models analyses are associated with regional climate modeling and a French station-based dataset of observations. The summer 21st century evolution of the maximum values of daily warm record-breaking temperatures is first examined in the observations and the high resolution simulation of the regional model. By 2100, an increase of these values is projected, with maximum changes between +6.6°C and +9.9°C in summer among the French regions. These projections assessed from a regional model may underestimate the changes. The multi-model mean estimate of the maximum increase of these values is indeed around +11.8°C in summer over France. Finally, regional modeling experiments of severe heatwaves in the climate of the end of the 21st century in Europe are performed. These severe heatwaves are selected cases from a global climate model trajectory. The experiments results show the role of the soil-atmosphere interactions in the amplification of the extreme temperatures during such future severe warm events. The occurrence of the heatwave is first caused by the atmospheric circulation, but the temperature anomaly can then be amplified according to the soil moisture content before the event, and thus the climatic conditions of the preceding weeks and months

During the system and software development process for distributed systems, the development of the overall system design is critical for correctness, performance, and reliability. The objective of this thesis is the improvement of methods and tools that can be used to obtain a correct design model for distributed system components automatically by deriving the design model from the global system requirements. Mainly, we are concerned with the transformation from a global requirements model to a distributed design model. The global requirements model describes the behavior of a distributed system in an abstract manner by defining the local actions to be performed by different roles which represent actors in the different system components. The distributed design model defines the behavior of each actor separately, including its local actions plus the exchange of coordination messages, which are necessary to assure that the actions are performed in the required order. In this work, we first consider a global requirements model in the form of partially ordered actions similar to High-level Message Sequence Chart (HMSC). We study the realizability of the global requirements, which is said to be directly realizable if a design model can be constructed without any coordination messages. We study some problems which prevent direct realizability, such as strict sequence, non-local choice, non-deterministic choice, termination race, and others, and show under which conditions these problems are absent and the global model is directly realizable. For the other cases, we show how a conforming design model can be obtained by introducing a minimal number of coordination messages. In this context, we also show under which conditions sequence numbers are required in the messages of a weak while loop. Then we study the automatic derivation of a distributed design model using a tool. In order to obtain an easily readable notation for the global requirements model, we adapt the HMSC notation to the UML Hierarchical State Machine (HSM) notation and extend this notation to describe the roles that participate in the actions of each state of the global behavior. A simple state represents some local actions of a single role, while a hierarchical state usually represents a collaboration between several roles. Then we describe a derivation algorithm that can be applied to a global model written in this proposed HSM notation and generates a distributable UML HSM model, which contains a hierarchical state machine for each role of the application. We implemented this derivation algorithm as a tool in the context of the Umple UML development environment. This tool takes a global requirements model written in the extended HSM notation as input and automatically generates a UML HSM model. The distributed implementation environment described in Zakariapour’s thesis is used for generating a distributed Java implementation, where each distributed component contains one Java run-time environment and realizes the behavior of one or several of the roles of the application. A Travel Management System illustrative example has been discussed to illustrate the representation of the global model using the extended HSM notation and to demonstrate the correctness of the generated design models by the tool.

This thesis is about regional development in the new global economy. Changes in the world economy, notably the trend toward multinational big business and an international division of labour, are affecting, in various ways and in varying degrees, those people and places that are part of this interdependent system. Nevertheless, one constant theme is becoming discernable: the operating rules of global capitalism are antagonistic to attempts by regions to develop a self-sustaining, self-reliant economy. The resulting crisis of development is an aspect of the new economic order that mainstream development paradigms of industrial society are ill-equipped to explain, let alone resolve. In an effort to come to grips with this crisis of development there has been a growing interest in the possibility of social and economic reconstruction at the regional and community level. This bottom-up approach, referred to here as Communal Cooperation, is being advocated as a more socially responsive and economically viable alternative to the dependence and underdevelopment that follow in the wake of functional integration into the international network of economic relations. However, as this thesis argues, Communal Cooperative strategies of self-management must be complemented with the kind of overall management and coordination that has become necessary in today's interdependent economy. The purpose of this thesis is to translate these general principles into practical terms by presenting a development strategy for the province of British Columbia. British Columbia is a resource economy, exporting its raw materials to the industrial centres of the world and, given the dynamics of economic globalism, there is little opportunity to break out of this mold and develop a self-sustaining, diversified economic base. The development options outlined in this thesis are designed to counteract this trend and ensure that international trade serves regional and community interests.
Applied Science, Faculty of
Community and Regional Planning (SCARP), School of
Graduate

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
Includes bibliographical references (p. 61-63).
by Theodore Vassilios Theodosopoulos.
Ph.D.

Global illumination models are used to simulate the complex lighting effects found in nature. This thesis investigates the wavelet radiance global illumination model and the extension of the wavelet radiance algorithm to support non-uniform rational B-spline (NURBS) surfaces. NURBS are a powerful mathematical form for representing freeform surfaces - NURBS are used in many rendering systems and therefore it is very useful to extend illumination models to support these surfaces.

The aim of this thesis is to improve our understanding of the distribution of stratospheric ozone which is determined by both dynamical and photochemical processes. This is of particular importance since ozone adsorbs incoming solar UV radiation which would otherwise be harmful to humans. In 1985 the Antarctic Ozone hole was discovered alerting the world to the impact human activity has had upon stratospheric ozone. In recent years a significant decline in ozone has also been detected at high northern latitudes during spring. This thesis uses numerical models of varying complexity in order to study the stratospheric circulation, and the chemistry occurring therein. The results from the model integrations described are compared to observations made by instruments on board the UARS satellite. A new stratospheric chemistry scheme is described. Simple box model studies show that this model is capable of simulating the almost complete removal of ozone seen to occur at certain altitudes during Antarctic spring. This experiment highlights interesting differences in the behaviour of chlorine compounds in the two hemispheres. Sensitivity studies are performed in order to determine the precise conditions required for severe ozone destruction. It is found that the average ozone destruction rate over the period of the integration is inversely proportional to the maximum C1ONO₂ mixing ratio produced by the model. The model shows some sensitivity to the ozone column used in the photolysis calculation, however it is not considered that sufficient improvement would be obtained by using a fully interactive photolysis scheme to justify the computational expense of this calculation. The new chemistry scheme is coupled to the SLIMCAT off-line model in order to study the 1991-92 northern hemisphere winter. It is found that if instead of using 2-dimensional model data to initialise the model a more realistic simulation is produced by using observations of long lived gases made by the UARS satellite. It is found that whilst the model is capable of reproducing ozone depletion, the denoxification within the model is too severe. This results in the deactivation of chlorine being unrealistically slow. In order to investigate the longer term variation of ozone a one year integration of the SLIMCAT model coupled to a parameterised chemistry scheme is performed. When the model results are compared to observations there is evidence that the model's simulation of lower stratosphere tropical dynamics is poor. Budget studies of N₂O reveal that the main cause of this problem is the lack of means continuity in this region of the model. When the experiment is repeated, imposing mass continuity on each isentropic surface, the resulting N₂O distribution is much more realistic.

L'ozone troposphérique (O3) est un gaz à effet de serre et un polluant atmosphérique majeur. Il est la source principale du radical hydroxyle OH, l'oxydant le plus important dans l'atmosphère, fortement réactif avec les composés organiques et inorganiques. Les concentrations globales d'ozone troposphérique ont augmenté considérablement depuis l'époque pré-industrielle en raison de l'accumulation des émissions anthropiques de précurseurs d'ozone. Mon travail de thèse consiste à étudier la variabilité spatiale et temporelle de l'ozone troposphérique aux échelles globale et régionale telle qu'elle est mesurée par le sondeur IASI (Infrared Atmospheric Sounding Interferometer). Deux instruments IASI ont été lancés à bord des satellites MetOp-A et MetOp-B en 2006 et 2012.La première partie de mon travail consiste en l'étude des mesures O3/IASI: sa sensibilité dans la troposphère, sa variabilité saisonnière et ses modes de transport. Le deuxième volet de mon travail de thèse repose sur des études ciblées. Celles-ci comprennent une première étude sur l'ozone, urbain et rural, et sa relation complexe avec le dioxide d'azote (NO2) mesuré depuis l'espace par GOME-2 (Global Ozone Monitoring Experiment) au-dessus de différentes villes de l'hémisphère nord. Une deuxième étude s'attache à expliquer la source des pics d'ozone observés en région méditerranéenne en été, en utilisant IASI et le modèle de chimie-transport WRF-Chem (Weather Research and Forecasting model coupled with Chemistry). Enfin, en utilisant ces deux jeux de données, je présente en troisième étude l'analyse de la mousson d'été en Asie de l'Est ainsi que son effet sur l'ozone troposphérique
Tropospheric ozone (O3) is an important greenhouse gas and air pollutant. It is the primary source of the most important oxidant in the atmosphere, the hydroxyl radical OH, that is highly reactive with organic and inorganic compounds. Global tropospheric O3 concentrations have been rising considerably since pre-industrial times as a result of the increase in the anthropogenic emissions of O3 precursors. In this thesis, I will study the temporal and spatial variability of tropospheric O3 on a global and regional scale as measured by IASI (Infrared Atmospheric Sounding Interferometer). The IASI instruments have been launched on-board the MetOp-A and MetOp-B satellites in 2006 and 2012.I first discuss the IASI/O3 measurements, their sensitivity in the troposphere and their seasonal variation and transport processes. I then perform more detailed and focused studies. Those include studying the urban and rural O3 and its relationship with nitrogen dioxyde (NO2) measured from GOME (Global Ozone Monitoring Experiment) over different cities in the Northern Hemisphere; investigating the summertime tropospheric O3 maxima over the Mediterranean region using IASI and the WRF-Chem (Weather Research and Forecasting model coupled with Chemistry) data; and finally, using both satellite and model data, I present my analysis of the East Asian monsoon variability and its effect on the tropospheric O3 column

Partendo dalla constatazione della sempre maggiore complessità del contesto economico e sociale nazionale ed internazionale, imputabile da un lato al processo di integrazione economico e monetario europeo, e dall'altro alla progressiva decentralizzazione dei poteri a livello regionale, la tesi intende proporsi come uno strumento analitico di supporto al decisore. A tal fine, in base a dati annui di fonte ISTAT-SVIMEZ per il periodo 1970-2003, viene sviluppato un modello econometrico regionale 'globale' per il mercato del lavoro italiano, estendendo un precedente modello mono-regionale proposto da Baussola (2003), ad un contesto pluri-regionale. Il modello conduce non solo a rappresentare soddisfacentemente i mercati regionali italiani, ma opera altresì efficacemente nel ricostruire i valori delle variabili a livello nazionale. Il modello si conferma robusto ed efficace nel rappresentare le realtà regionali, anche nell'ottica di analisi propria dell'econometria delle serie storiche.
The starting point of this thesis is the remark that recent decades have been characterized by a rising complexity in the economic and political context both at the national and international level. This is due both to the European economic and monetary integration process and to the regional decentralisation process. With the aim of providing a useful tool of analysis for the decision-maker,. a 'global' regional model for the Italian labour market has been constructed on the basis of annual data from ISTAT-SVIMEZ over the 1970-2003 period. This model could be viewed as an extension to a multi-regional framework of the previous one-region model developed by Baussola (2003). The model shows good performance not only in representing regional labour market specificities, but also in reproducing national variable values. It is also robust and effective in a time-series context.

Partendo dalla constatazione della sempre maggiore complessità del contesto economico e sociale nazionale ed internazionale, imputabile da un lato al processo di integrazione economico e monetario europeo, e dall'altro alla progressiva decentralizzazione dei poteri a livello regionale, la tesi intende proporsi come uno strumento analitico di supporto al decisore. A tal fine, in base a dati annui di fonte ISTAT-SVIMEZ per il periodo 1970-2003, viene sviluppato un modello econometrico regionale 'globale' per il mercato del lavoro italiano, estendendo un precedente modello mono-regionale proposto da Baussola (2003), ad un contesto pluri-regionale. Il modello conduce non solo a rappresentare soddisfacentemente i mercati regionali italiani, ma opera altresì efficacemente nel ricostruire i valori delle variabili a livello nazionale. Il modello si conferma robusto ed efficace nel rappresentare le realtà regionali, anche nell'ottica di analisi propria dell'econometria delle serie storiche.
The starting point of this thesis is the remark that recent decades have been characterized by a rising complexity in the economic and political context both at the national and international level. This is due both to the European economic and monetary integration process and to the regional decentralisation process. With the aim of providing a useful tool of analysis for the decision-maker,. a 'global' regional model for the Italian labour market has been constructed on the basis of annual data from ISTAT-SVIMEZ over the 1970-2003 period. This model could be viewed as an extension to a multi-regional framework of the previous one-region model developed by Baussola (2003). The model shows good performance not only in representing regional labour market specificities, but also in reproducing national variable values. It is also robust and effective in a time-series context.

Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Applied Mathematics and Scientific Computation Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Este trabalho avaliou a qualidade das previsões climáticas sazonais realizadas com dois modelos climáticos globais, o Climate Forecast System version 2 (CFSv2) e o modelo do Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), e com duas versões do Regional Climate Model: versões 4.3 e 4.5. O RegCM4.3 foi dirigido com condições iniciais e de fronteira provenientes do sistema CFSv2, o qual foi chamado de RegCFSv2, já o RegCM4.5 foi dirigido com condições iniciais e de fronteira provenientes do modelo CPTEC, com duas parametrizações cumulus diferentes, Kain-Fritsch e Emanuel, estas previsões foram chamadas de RegCPTECKF e RegCPTECEman, respectivamente. Ao todo são analisados doze trimestres que consideram médias por conjunto (ensembles) com início em 6 diferentes datas para o CFSv2 e RegCFSv2 e 5 para o CPTEC. As previsões RegCPTECKF e RegCPTECEman não possuem ensemble, apenas uma previsão cada. A precipitação prevista foi comparada com dados do Climate Prediction Center (CPC) e do Tropical Rainfall Measuring Mission (TRMM), a temperatura do ar a 2 metros foi comparada com dados da ERA-Interim e do CFSR e o vento nos níveis de 250 e 850 hPa com a ERA-Interim. Foram realizadas análises considerando todo o Brasil e subdomínios: Sudeste do Brasil (SDE), Nordeste do Brasil (NDE), Amazônia (AMZ) e Sul do Brasil (SUL). A primeira parte desse estudo valida a circulação em 250 e 850 hPa prevista pelos modelos globais. Embora os modelos apresentem vieses na intensidade do vento e, às vezes, na direção, em geral, representam as principais características da circulação atmosférica na América do Sul. Portanto, uma vez que os modelos globais mostram destreza em simular as características da circulação atmosférica sobre o Brasil e adjacências, estes serviram de condições de fronteira para as previsões com o RegCM. A etapa seguinte consistiu em validar as previsões de precipitação e temperatura dos modelos globais e regional. As médias por subdomínios mostraram que a precipitação no SUL não conseguiu ser bem prevista em valor médio por nenhuma das previsões, mas a temperatura foi muito bem representada. No subdomínio AMZ, a precipitação foi bem representada por todas as previsões e a temperatura possuiu melhor representatividade pelas previsões RegCPTECKF e RegCPTECEman. A RegCPTECEman foi a previsão que melhor representou a média da precipitação nas regiões NDE e SDE. As previsões CPTEC e RegCPTECEman foram as que melhor simularam a média espacial da temperatura na região NDE. Já a região SDE foi melhor representada pelo CPTEC e RegCPTECKF em comparação com o observado na ERA-Interim. A análise dos dias consecutivos secos (limiar inferior ao percentil de 10%) e úmidos (limiar superior ao percentil de 90%), por trimestre, nos subdomínios em estudo, indica que o RegCPTECKF foi o modelo que melhor simulou os limiares inferiores com relação aos valores observados (CPC e TRMM), e o total de períodos previstos. Esse estudo mostrou que para a previsão de temperatura do ar, o modelo regional adiciona valor às previsões do modelo global CPTEC, enquanto que para a precipitação depende da região analisada.

How does the recent wave of preferential trading arrangements affect, the incentives for further trade liberalization of member states, and the possibility of obtaining global free trade? And are there any differences in this aspect between custom unions and other forms of preferential trading arrangements? These questions are well debated and have divided international trade researchers into two camps, one in favour for preferential trading arrangements and the other side against them. I have used well acknowledged researchers in the area of international trade theory to make a literature study of the above mentioned key elements in the debate. When comparing the two sides I have focused mainly on their differences, assumptions and results. I have come to the conclusion that there is nothing to be alarmed by of the wave of regionalism that’s occurring in the world today, but caution should be applied and more research in this area is necessary before any certain conclusions can be drawn. Free trade association seems to be welfare enhancing in general, with a few exceptions. I have found that the crucial points of what affect Free Trade Agreements will have on trade liberalization seems to be whether they are open or closed, how asymmetric the world is and the size of the trading blocs. The matter concerning custom unions are more alarming and seems to harm further trade liberalization in many aspects but this area also needs more research to give more reliable answers.

La tendance au réchauffement d'origine anthropique observée au cours du XXè siècle en Europe est ponctuée par des fluctuations expliquées en partie par la variabilité interne du climat. Les mécanismes physiques entre la Variabilité Atlantique Multidécennale (AMV), dont la composante interne module une partie de la variabilité atmosphérique, et le climat européen sont étudiés dans cette thèse. Une étude des modèles climatiques montre une grande diversité dans la simulation de la téléconnexion entre l'AMV et la température estivale en Europe. La sous-estimation moyenne de son intensité par rapport aux observations contribue notamment à expliquer les incertitudes qui entachent les prévisions décennales du climat. Des expériences numériques utilisées pour isoler les mécanismes d'influence de l'AMV sur le climat européen indiquent que l'AMV est susceptible de significativement moduler la température, les précipitations et l'occurrence d'événements extrêmes, en hiver et en été
The anthropogenic warming trend observed during the 20th century in Europe is characterized by fluctuations, which are partly explained by internal climate variability. The physical mechanisms between the Atlantic Multidecadal Variability (AMV, whose internal component contributes to shape atmospheric variability), and the European climate are investigated in this thesis. A comprehensive study of climate models shows a great diversity in the simulation of the teleconnection between the AMV and European summer temperature. The underestimation of its intensity relative to the observations contributes to explain the uncertainties within the decadal climate predictions. Numerical experiments used to assess the mechanisms of influence of the AMV on the European climate indicate that the AMV is likely to significantly modulate temperature, precipitation and the occurrence of extreme events in winter and summer

Ocean tides worldwide have exhibited secular changes in the past century, simultaneous with a global secular rise in mean sea level (MSL). The combination of these two factors contributes to higher water levels, and may increase threats to coastal regions and populations over the next century. Equally as important as these long-term changes are the short-term fluctuations in sea levels and tidal properties. These fluctuations may interact to yield locally extreme water level events, especially when combined with storm surge. This study, presented in three parts, examines the relationships between tidal anomalies and MSL anomalies on yearly and monthly timescales, with a goal of diagnosing dynamical factors that may influence the long-term evolution of tides in the Pacific Ocean. Correlations between yearly averaged properties are denoted tidal anomaly trends (TATs), and will be used to explore interannual behavior. Correlations of monthly averaged properties are denoted seasonal tidal anomaly trends (STATs), and are used to examine seasonal behavior. Four tidal constituents are analyzed: the two largest semidiurnal (twice daily) constituents, M2 and S2, and the two largest diurnal (once daily) constituents, K1 and O1.

Part I surveys TATs and STATs at 153 Pacific Ocean tide gauges, and discusses regional patterns within the entire Pacific Ocean. TATs with statistically significant relations between MSL and amplitudes (A-TATs) are seen at 89% of all gauges; 92 gauges for M2, 66 for S2, 82 for K1, and 59 for O1. TATs with statistically significant relations between tidal phase (the relative timing of high water of the tide) and MSL (P-TATs) are observed at 55 gauges for M2, 47 for S2, 42 for K1, and 61 for O1. Significant seasonal variations (STATs) are observed at about a third of all gauges, with the largest concentration in Southeast Asia. The effect of combined A-TATs was also considered. At selected stations, observed tidal sensitivity with MSL was extrapolated forward in time to the predicted sea level in 2100. Results suggest that stations with large positive combined A-TATs produce total water levels that are greater than those predicted by an increase in MSL alone, increasing the chances of high-water events.

Part II examines the mechanisms behind the yearly (TAT) variability in the Western Tropical Pacific Ocean. Significant amplitude TATs are found at more than half of 26 gauges for each of the two strongest tidal constituents, K1 (diurnal) and M2 (semidiurnal). For the lesser constituents analyzed (O1 and S2), significant trends are observed at ten gauges.

Part III analyzes the seasonal behavior of tides (STATs) at twenty tide gauges in the Southeast Asian waters, which exhibit variation by 10 – 30% of mean tidal amplitudes. A barotropic ocean tide model that considers the seasonal effects of MSL, stratification, and geostrophic and Ekman velocity is used to explain the observed seasonal variability in tides due to variations in monsoon-influenced climate forcing, with successful results at about half of all gauges. The observed changes in tides are best explained by the influence of non-tidal velocities (geostrophic and Ekman), though the effect of changing stratification is also an important secondary causative mechanism.

From the results of these surveys and investigations, it is concluded that short-term fluctuations in MSL and tidal properties at multiple time scales may be as important in determining the state of future water levels as the long-term trends. Global explanations for the observed tidal behavior have not been found in this study; however, significant regional explanations are found at the yearly time scale in the Solomon Sea, and at the seasonal time scale in Southeast Asia. It is likely that tidal sensitivity to annual and seasonal variations in MSL at other locations also are driven by locally specific processes, rather than factors with basin-wide coherence. (Abstract shortened by ProQuest.)

Diffusion-weighted MRI (DW-MRI) is a powerful in vivo imaging technique that is particularly sensitive to the underlying microstructure of white matter tissue in the brain. Many models of the DW-MRI signal exist that allow us to relate the signals we measure to various aspects of the tissue structure, including measures of diffusivity, cellularity and even axon size. From histology, we know that many of these microstructure measures display distinct patterns of variation on length scales greater than the average voxel size. However very few methods exist that use this spatial coherence to inform and guide parameter estimation. Instead, most techniques treat each voxel of data independently. This is particularly problematic when estimating parameters such as axon radius which only weakly influence the signal, as the resulting estimates are noisy. Several methods have been proposed that spatially smooth parameter estimates after fitting the model in each voxel. However if the parameter estimates are very noisy, the underlying trend is likely to be obscured. These methods are also unable to account for spatial coupling that may exist between the various parameters. This thesis introduces a novel framework, the Regional Variation Model (RVM), which exploits the underlying spatial coherence within white matter tracts to estimate trends of microstructure variation across large regions of interest. We fit curves describing parameter variation directly to the diffusion-weighted signals which should capture spatial changes in a more natural way as well as reducing the effects of noise. This allows for more precise estimates of a range of microstructure indices, including axon radius. The resulting curves, which show how microstructure parameters vary spatially through white matter regions, can also be used to detect groupwise differences with potentially greater power than traditional methods.

Tuna can travel thousands of kilometers throughout their lifetime, and are often found in the waters of several nations and the high seas. These ``straddling stocks" are difficult to manage due to competition between the large number of interested fishing nations, all of which can be asymmetric in their economies, management capacity and conservation concerns. This is compounded by the possibility of new members and free riders. It is no surprise then, that tuna fisheries management has, by and large, been unsuccessful in promoting sustainable fisheries. Populations of several of the world's tuna species are fully or over-exploited. This dissertation identifies and addresses areas where improvements in the management of global and regional tuna fisheries may facilitate the continued contribution of these fisheries to livelihoods and food security. I analyze private and social resource rent derived from fishing for different tuna species and by different gear types. From these results I identify key management targets. Management efforts are formalized through Regional Fisheries Management Organizations (RFMOs), groups which are mandated to promote cooperative agreements and fair and equitable allocation approaches. Stable cooperative agreements, however, have been hard to come by for tuna RFMOs, in part because the issue of allocations has not been appropriately targeted. I propose a combined socio-economic and ecological approach formulated from the perspective of fisheries benefits, as opposed to just catch, which could facilitate stable cooperative agreements for sustaining tuna stocks into the distant future. Tuna fisheries in the western and central Pacific provide over half of the world's tuna, but lack of effective management capacity in Indonesia and the Philippines threatens the sustainability of these fisheries. I argue that countries that fish in this region, most specifically Papua New Guinea, would be wise to help facilitate improved management capacity in these countries. One of the major management challenges in this region is the bycatch of juvenile yellowfin and bigeye tuna in the skipjack purse seine fishery. Through applied game-theoretic modelling, I conclude that reduction in juvenile bycatch brought about by cooperative management of these fisheries would provide long-term ecological and economic benefits.

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Die Zukunft liegt bereits heute schon im Internet der Dinge, Daten, Dienste und Personen. Informations- und Kommunikationstechnologien (IKT) beeinflussen vermehrt die alltäglichen Abläufe, übernehmen im Ernstfall lebenserhaltende Körperfunktionen, unterstützen Arbeits- und Produktionsprozesse und halten Einzug in unsere Wohnbereiche. Dabei rückt der Gedanke einer anwendungsnahen und integrierten Sicht von Software zunehmend in den Vordergrund und verlangt deshalb interdisziplinäre Ansätze. Eine frühzeitige technische Abstimmung zwischen Soft- und Hardware sowie unterschiedlichen technischen Öko-Systemen wird dabei notwendiger und fordert Politik, Wissenschaft und Wirtschaft in gleichem Maße. Das Innovationsforum open4INNOVATION2012 am 9.Mai bot dazu Praktikern und Akademikern eine Plattform für den interdisziplinären und fachbereichsübergreifenden Austausch zu neuen und anwendungsnahen IKT-Ansätzen. Unter dem Motto regional kooperativ, global innovativ galt es dabei regional politische, wirtschaftliche und wissenschaftliche Kompetenzen zu bündeln, um globale Märkte erfolgreich zu bestreiten. In dem vorliegenden Tagungsband finden Sie die Beiträge des Fachforums, welches ein Hauptformat der Veranstaltung darstellte. Zusätzlich kam es auf dem Innovationsforum open4INNOVATION2012 erstmals zur aktiven Vernetzung sächsischer Forschergruppen, deren wissenschaftlicher Schwerpunkt die Robotik ist. Auf diesem ersten sächsischen Robotertreffen stand vor allem die Arbeit mit humanoiden Robotern im Mittelpunkt.

Thesis (M.A. in National Security Affairs)--Naval Postgraduate School, December 2004.
Thesis advisor(s): Donald Abenheim, Roger McDermott. Includes bibliographical references (p. 67-60). Also available online.