Dissertationen zum Thema „Lois climatiques“
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Boucharel, Julien. „Modes de variabilité climatique dans l'océan Pacifique tropical : quantification des non-linéarités et rôle sur les changements de régimes climatiques“. Phd thesis, Université Paul Sabatier - Toulouse III, 2010. http://tel.archives-ouvertes.fr/tel-00720706.
Der volle Inhalt der QuelleBoucharel, Julien. „Modes de variabilité climatique dans l'océan Pacifique tropical : quantification des non-linéarités et rôle sur les changements de régimes climatiques“. Phd thesis, Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1663/.
Der volle Inhalt der QuelleENSO is the dominant mode of climate variability in the Pacific, having widespread socio-economical impacts. ENSO characteristics have been observed to exhibit substantial irregular variability from decadal to millennial timescales. The origin of such richness in ENSO variability timescales is likely due to the combined effects of timescales interaction processes within the tropical Pacific (through self-sustained nonlinear dynamics) and to external forcing (e. G. Volcanic activity, changes in greenhouse gases. . . ). In this thesis, we propose a new statistical framework that allows documenting high statistical moments in observed and simulated timeseries and that provides a robust estimation of nonlinearity in the tropical coupled system. As a first step, from the analysis of long-term CGCM simulations and extended reconstructed SST data sets, it is demonstrated that an interaction between interdecadal mean state changes in the tropical Pacific and extreme El Niño events probability occurs. This supports the hypothesis of ENSO variability being rectified at a wide range of frequencies by the slowly varying mean state through nonlinear processes phase-locked to the seasonal cycle alternatively in the Western and Eastern tropical Pacific. We then question to which extent the increase in greenhouse gases can alter the ENSO properties with a focus on its nonlinear character. Taking advantage of the IPCC database and different projections scenarios, nonlinearities are diagnosed in a model ensemble; and a relevant metric of the change in nonlinearity due to climate change is defined. This new metric allows highlighting a zonal see-saw in nonlinearity patterns associated with the change in El Niño characteristics observed in recent years. The traditional 20th century El Niño fingerprint, localized in the Cold Tongue, is robustly displaced westward in a warmer climate leading to El Niño Modoki-type patterns. We relate this switch in El Niño types to a change in nonlinearity pattern from present-day climate to a warmer climate. Secondly, we focused on the eastern tropical Pacific and the Humboldt Current System modelling and especially on the ability of Galapagos Islands and intra-seasonal activity in rectifying their mean state. Unlike recent studies, we put into perspective the role of this archipelago in altering this regional mean state. On the other hand, the intra seasonal Kelvin waves activity has the potential to revitalize the local mean circulation, the vertical stratification and therefore the Eastern Pacific dynamics, which in turn may have the potential to affect ENSO through upscaling effects
Gastineau, Guillaume. „Les changements de la circulation atmosphérique tropicale et conséquences lors du changement climatique“. Paris 6, 2008. http://hal.upmc.fr/tel-01332290.
Der volle Inhalt der QuelleBenchora, Inessa. „Impact of Transition Risk on Stock Returns“. Electronic Thesis or Diss., Orléans, 2024. http://www.theses.fr/2024ORLE1010.
Der volle Inhalt der QuelleTransition risk, inherent in the shift to a low-carbon economy, presents significant challenges and opportunities for financial markets. This thesis aims to quantify and analyze the influence of this risk on stock returns, taking into account regulatory, technological, and consumer and investor preference developments. Taking part initially in the debate on the most appropriate measure to approximate a company’s contribution to transition risk, in Chapter 1, we propose the use of verified carbon emissions to assess the impact of transition risk on companies participating in the EU ETS. Our results show that the emissions trading system alters the risk-return profile of stocks, which can provide a financial incentive to consider emissions in investment decisions. Next, recognizing the pivotal role of central banks in the transition to a low-carbon economy, Chapter 2 provides an evaluation of the environmental footprint of U.S. monetary policy concerning transition risk. The main conclusion of non-neutrality in U.S. monetary policy, favoring polluting companies, leads to the third chapter. This chapter, also focused on the United States, explores how transition risk is taken into account in market valuation and how climate regulation can influence this integration. Our results suggest that the long-term impact of U.S. laws on the relationship between carbon emissions and stock returns needs strengthening to ensure its sustainability. Currently, legislative measures have a more pronounced effect in the medium term, but their sustainability remains uncertain. In conclusion, these chapters aim to enable a better integration of transition risk into stock evaluation by investors, which would empower regulatory authorities and financial market participants to develop more suitable policies and preventive measures against this risk
Coron, Alain. „Analyse de signaux climatiques et solaires“. Grenoble INPG, 1998. http://www.theses.fr/1998INPG0037.
Der volle Inhalt der QuelleBréant, Camille. „Variabilité régionale de la densification de la neige polaire lors des grandes transitions climatiques“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV104/document.
Der volle Inhalt der QuelleThe phasing between increases in temperature and greenhouse gas concentrations during large climatic variations in the past is classically estimated using analyses in polar ice cores, in the ice phase for the temperature and in the gas phase (trapped air bubbles) for the concentration of greenhouse gases. This phasing is still insufficiently constrained and solving this problem requires a better understanding of the mechanical process of snow to ice metamorphism near to the top of the ice sheet (i.e. the firn, about 100 m deep). In the absence of melting, the transformation of snow (a material with open porosity in contact with the atmosphere) into ice (a material containing isolated bubbles) occurs progressively as a response to temperature gradients near the surface, and the weight of overlying snow in deeper layers. Depending on temperature and precipitation conditions, this process occurs in a few decades to several millennia and a ~100 meters depth range. It controls the age difference between the ice and the entrapped gases. Predicting the gas trapping depth is a major issue in paleoclimatology, especially in order to understand the phasing between temperature changes and changes in greenhouse gas concentrations.A thermo-mechanical model of snow densification has been developed at LGGE, it includes the main mechanical processes, the thermal properties of ice, and gas trapping criteria. The model performances can be tested and improved using experimental studies of modern firns (density, open/closed porosity ratio, etc). For firnification under ancient climates, measurements of isotopes of inert gases (d15N et d40Ar) in the air trapped in ice cores provide direct informations about past variations of firn structure (e.g. diffusive zone thickness). Large differences between firn densification model outputs and gas isotopic data are obtained in Antarctica, and imply a large uncertainty on past climatic reconstructions. Understanding this discrepancy is a major issue in paleoclimatology.As part of this thesis work, we took into account the effects of the temperature dependence of activation energies and impurities (dust) on the firn densification speed. It allowed to reconcile the model results with available data. The modified model results show an overall consistency with measured density profiles of present-day polar firns and isotopes of inert gases over deglaciations (also called terminations). We also analyze new high resolution measurements of d15N and d40Ar over Terminations 2 (129-138ka) and 3 (243-251ka) on the Dome C and Vostok ice cores. We have shown that the different evolutions of d15N between different sites and different deglaciations are largely explained by differences in accumulation rates that control the snow/ice transition depth. We also showed that the use of air isotopes was an important complement to the use of water isotopes to constrain local climatic dynamics in eastern Antarctica during deglaciations
Bréant, Camille. „Variabilité régionale de la densification de la neige polaire lors des grandes transitions climatiques“. Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV104.
Der volle Inhalt der QuelleThe phasing between increases in temperature and greenhouse gas concentrations during large climatic variations in the past is classically estimated using analyses in polar ice cores, in the ice phase for the temperature and in the gas phase (trapped air bubbles) for the concentration of greenhouse gases. This phasing is still insufficiently constrained and solving this problem requires a better understanding of the mechanical process of snow to ice metamorphism near to the top of the ice sheet (i.e. the firn, about 100 m deep). In the absence of melting, the transformation of snow (a material with open porosity in contact with the atmosphere) into ice (a material containing isolated bubbles) occurs progressively as a response to temperature gradients near the surface, and the weight of overlying snow in deeper layers. Depending on temperature and precipitation conditions, this process occurs in a few decades to several millennia and a ~100 meters depth range. It controls the age difference between the ice and the entrapped gases. Predicting the gas trapping depth is a major issue in paleoclimatology, especially in order to understand the phasing between temperature changes and changes in greenhouse gas concentrations.A thermo-mechanical model of snow densification has been developed at LGGE, it includes the main mechanical processes, the thermal properties of ice, and gas trapping criteria. The model performances can be tested and improved using experimental studies of modern firns (density, open/closed porosity ratio, etc). For firnification under ancient climates, measurements of isotopes of inert gases (d15N et d40Ar) in the air trapped in ice cores provide direct informations about past variations of firn structure (e.g. diffusive zone thickness). Large differences between firn densification model outputs and gas isotopic data are obtained in Antarctica, and imply a large uncertainty on past climatic reconstructions. Understanding this discrepancy is a major issue in paleoclimatology.As part of this thesis work, we took into account the effects of the temperature dependence of activation energies and impurities (dust) on the firn densification speed. It allowed to reconcile the model results with available data. The modified model results show an overall consistency with measured density profiles of present-day polar firns and isotopes of inert gases over deglaciations (also called terminations). We also analyze new high resolution measurements of d15N and d40Ar over Terminations 2 (129-138ka) and 3 (243-251ka) on the Dome C and Vostok ice cores. We have shown that the different evolutions of d15N between different sites and different deglaciations are largely explained by differences in accumulation rates that control the snow/ice transition depth. We also showed that the use of air isotopes was an important complement to the use of water isotopes to constrain local climatic dynamics in eastern Antarctica during deglaciations
Desprat, Stéphanie. „Réponses climatiques marines et continentales du Sud-Ouest de l'Europe lors des dernières interglaciaires et des entrées en glaciations“. Bordeaux 1, 2005. http://www.theses.fr/2005BOR12963.
Der volle Inhalt der QuelleThe main purpose of this work is to characterise the climatic variability of the last five isotopic interglacials which have occurred during the last 450, 000 years, in particular that of marine isotope stage 11, 9 and 7. For that, a multiproxy study (pollen, assemblages of planktic foraminifera, and planktic and benthic delta^18O) was performed from NW Iberian margin deep-sea cores. All isotopic interglacials show a similar climate dynamic related to astronomical forcing cyclicity, on which abrupt climatic oscillations are superimposed. However, they differ from each other by the amplitude of the climatic phases and the forest vegetation succession during warm periods. The marine and continental realms synchronously respond to climate changes. However, a time-lag is detected between temperature variations and ice volume changes. The direct land-sea-ice correlation highlights interactions between insolation, ice volume and vegetation during glacial inception
Gay, Laura. „Processus d'Ornstein-Uhlenbeck et son supremum : quelques résultats théoriques et application au risque climatique“. Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC025/document.
Der volle Inhalt der QuelleForecasting and assessing the risk of heat waves is a crucial public policy stake. Evaluate the probability of heat waves and their severity can be possible by knowing the temperature in continuous time. However, daily extremes (maxima and minima) might be the only available data. The Ornstein-Uhlenbeck process is commonly used to model temperature dynamic. An estimation of the process parameters using only daily observed suprema of temperatures is proposed here. This new approach is based on a least square minimization using the cumulative distribution function of the supremum. Risk measures related to heat waves are then obtained numerically. In order to calculate explicitly those risk measures, it can be useful to have the joint law of the Ornstein-Uhlenbeck process and its supremum. The study is _rst limited to the joint density / distribution of the endpoint and supremum of the Ornstein-Uhlenbeck process. This probability admits a density, solution of the Fokker-Planck equation and explicitly obtained as an expansion involving parabolic cylinder functions. The proof of the density expression relies on a decomposition on a Hilbert basis of the space via a spectral method. We also study the oscillating Ornstein-Uhlenbeck process, which drift parameter is piecewise constant depending on the sign of the process. The Laplace transform of this process hitting time is determined and we also calculate the probability for the process to be positive on a fixed time
Wary, Mélanie. „Rôle des conditions océaniques et des ice-shelves en périphérie des calottes européennes lors des événements climatiques abrupts de la dernière période glaciaire“. Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0316/document.
Der volle Inhalt der QuelleThe last glacial period was punctuated by abrupt climatic events known as Dansgaard-Oeschger and Heinrich events. Many studies have focused on this millennial climatic variability, but several uncertainties remain. The present work aims at improving our knowledge on this topic through the study of the hydrographical changes recorded in two marine archives retrieved off Faeroes. Our main results, based on a multiproxy approach, reveal a paradoxical scheme in the Norwegian Sea where cold episodes (stadials, including Heinrich events) are characterized by relatively warm sea-surface temperatures (especially during summer) and a reduced sea-ice cover, and warm periods (interstadials) are marked by a reverse pattern with cold sea surface conditions and extended sea ice cover. The atypical stadial features seem to be related to enhanced advection of warm Atlantic waters in the Nordic Seas, combined to a subpolar North-Atlantic and adjacent seas basin-wide subsurface warming. These two processes seem to play a key role in the destabilization of boreal ice-shelves and ice-sheets, and in fine to their final collapse and subsequent iceberg discharges. Our work also allows us to identify the main mechanisms responsible for Atlantic Meridional Overturning Circulation changes and associated atmospheric temperature variations. On the basis of our results and of those coming from previous studies, we thus propose a new hydrographical scenario which could explain the abrupt climate events of the last glacial period
Burckel, Pierre. „Utilisation du rapport (231Pa/230Th) des sédiments marins pour caractériser les changements de circulation océanique lors des variations climatiques de la dernière période glaciaire“. Thesis, Versailles-St Quentin en Yvelines, 2014. http://www.theses.fr/2014VERS0051/document.
Der volle Inhalt der QuelleIn this thesis, I reconstruct the dynamic of the Atlantic Meridional Overturning Circulation (AMOC) during fast climate changes of the last glacial period. I find that the AMOC upper circulation cell started to slowdown 1420 ± 250 (1σ) and 690 ± 180 (1σ) years before the southward shifts of the Inter Tropical Convergence Zone associated with Heinrich Stadial 2 and Heinrich Stadial 4, respectively. I therefore confirm that an AMOC slowdown could be at the origin of the ITCZ shifts that occured during Heinrich Stadials and provide the first precise estimate of the phasing between these two climate variables. Based on these results I propose a mechanism explaining the difference between Heinrich and Dansgaard-Oeschger stadials.Using modeling results, I show that the Atlantic Ocean circulation during periods of higher Greenland temperatures (interstadials) was markedly different from that of the Holocene. Two overturning cells were likely active in the Atlantic Ocean: an upper overturning circulation cell initiated by northern-sourced deep water flowing southward above ~2500 m depth at the equator, and a lower overturning circulation cell initiated by southern sourced deep water flowing northward below ~4000 m depth at the equator. The overturning rate of the upper overturning cell was likely lower than that of present-day North Atlantic Deep Water. At the onset of Heinrich Stadials, the structure of the AMOC significantly changed, and southern-sourced deep-waters likely dominated the equatorial Atlantic Ocean below 1300 m depth
Burckel, Pierre. „Utilisation du rapport (231Pa/230Th) des sédiments marins pour caractériser les changements de circulation océanique lors des variations climatiques de la dernière période glaciaire“. Electronic Thesis or Diss., Versailles-St Quentin en Yvelines, 2014. http://www.theses.fr/2014VERS0051.
Der volle Inhalt der QuelleIn this thesis, I reconstruct the dynamic of the Atlantic Meridional Overturning Circulation (AMOC) during fast climate changes of the last glacial period. I find that the AMOC upper circulation cell started to slowdown 1420 ± 250 (1σ) and 690 ± 180 (1σ) years before the southward shifts of the Inter Tropical Convergence Zone associated with Heinrich Stadial 2 and Heinrich Stadial 4, respectively. I therefore confirm that an AMOC slowdown could be at the origin of the ITCZ shifts that occured during Heinrich Stadials and provide the first precise estimate of the phasing between these two climate variables. Based on these results I propose a mechanism explaining the difference between Heinrich and Dansgaard-Oeschger stadials.Using modeling results, I show that the Atlantic Ocean circulation during periods of higher Greenland temperatures (interstadials) was markedly different from that of the Holocene. Two overturning cells were likely active in the Atlantic Ocean: an upper overturning circulation cell initiated by northern-sourced deep water flowing southward above ~2500 m depth at the equator, and a lower overturning circulation cell initiated by southern sourced deep water flowing northward below ~4000 m depth at the equator. The overturning rate of the upper overturning cell was likely lower than that of present-day North Atlantic Deep Water. At the onset of Heinrich Stadials, the structure of the AMOC significantly changed, and southern-sourced deep-waters likely dominated the equatorial Atlantic Ocean below 1300 m depth
Mallet, Paul-Etienne. „Polar lows dans l'hémisphère Nord : influence de l'environnement de grande échelle, de sa variabilité et de ses modifications avec le changement climatique“. Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00932363.
Der volle Inhalt der QuelleWardziak, Thomas. „Climat et biodiversité : application de récents développements méthodologiques à l'étude et la modélisation des pertes en eau par évaporation chez un amphibien“. Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10135/document.
Der volle Inhalt der QuelleLn a context of climate change, it is critical to predict how organisms might be affected in their physical relations with environment. Amphibians are among the vertebrate groups the most affected by ecological changes, because of permanent transepidermal evaporative water loss (TEWL) through their skin. My thesis aims at setting up approaches to measure and model accurately the functional skin surface areas that contribute to TEWL, establishing laws of water transfer between an amphibian and its physical environment, and providing understanding on physiological responses to the skin pathogen Batrachochytrium dendrobatidis. We conducted experiments on adult males of the palmate newt (Lissotriton helveticus) during their terrestrial phase. Our results suggest that L. helveticus did not show any physiological adaptations to restrain TEWL. The ways to reduce TEWL result essentially in the expression of a stereotyped "$"-shaped water-conserving posture. We used a Magnetic Resonance lmaging-based 3D reconstruction method to generate 3D geometries of newt that is suitable for measuring skin surface areas, and for simulation purposes. We successfully performed 3D numerical analysis of TEWL, and proposed an original relationship to estimate TEWL rates in a large range of temperature and humidity. Finally, our results support the epidermal dysfunction hypothesis, which suggests that B. dendrobatidis compromises the ability of amphibians to rehydrate. My thesis would contribute to open new approaches to the science of amphibian water relations, and improve our knowledge of the effects of ecological changes on organisms
Ndao, Marietou. „Dynamiques et gestion environnementales de 1970 à 2010 des zones humides au Sénégal : étude de l'occupation du sol par télédétection des Niayes avec Djiddah Thiaroye Kao (à Dakar), Mboro (à Thiès et Saint-Louis)“. Phd thesis, Université Toulouse le Mirail - Toulouse II, 2012. http://tel.archives-ouvertes.fr/tel-00718050.
Der volle Inhalt der QuelleNdao, Mariétou. „Dynamiques et gestion environnementales de 1970 à 2010 des zones humides au Sénégal : étude de l'occupation du sol par télédétection des Niayes avec Djiddah Thiaroye Kao (à Dakar), Mboro (à Thiès et Saint-Louis)“. Thesis, Toulouse 2, 2012. http://www.theses.fr/2012TOU20018/document.
Der volle Inhalt der QuelleThe “Niayes”, coastal wetlands of Senegal, constitute fragile ecosystems that are rich inbiodiversity while traditionally being gardening areas in the “Sahelien” environment. The bigdrought of the 1970s that struck all the Sahel countries also affected the “Niayes” by an influxof rural populations coming from inside the country in search of livelihood. Besides theextreme drought, mass migration considerably increased the proprietary pressure and at thesame time generated an uncontrolled urbanization, especially around the big agglomerationsand agricultural development: both of them undermine the environmental value of thesecoastal ecosystems. In recent years, we have witnessed particularly rainy seasons. This returneof rainfall involved in urbanized areas causes flooding, accompanied by precarious sanitaryconditions for the most unprivileged populations. The rainfall variability, risk of naturalappearance, is added to anthropogenic risk factors such as the non-mastered regionalplanning, the failure of the regulatory framework, and the pollution from various agriculturaland industrial sources.This thesis, after having introduced the concept of wet zones and having presented the Niayesof the Great Coast in general, and of the three study areas (Pikine, outskirts of Dakar; Mboro,Thies region; and Saint-Louis) in particular, traces their environmental problems and variouspolitical differences. Land use of the Niayes is analysed by using remote sensing data for theperiod 1986-2010 to confront its evolution to the management of the sensible ecosystems andquestion the relevance of the implemented politics in the spirit of sustainable development
Sbeiti, Abed al latiff. „Effet du changement climatique sur la réponse des plantes et des pathogènes, lors du développement de la maladie racinaire provoquée par les champignons pathogènes du sol du genre verticillium, chez deux espèces du genre médicago“. Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0064/document.
Der volle Inhalt der QuelleWe were interested to evaluate the influence of climate change on net patterns of plants responses to pathogens. In this work, we studied the effects of temperature increase (20 °, 25 ° and 28 ° C) on early phenotype (symptoms of disease) and on fitness at the end of growth cycle on different accessions and nodulation mutants of the legume model plant Medicago truncatula, inoculated by the root pathogen Verticillium adapted to different temperatures. The behavior of cultivated varieties of alfalfa (Medicago sativa) in these conditions was also analyzed. The work is divided into 3 parts. In the first part, we identified among 12 strains of Verticillium spp., a cold strain (VA1) and a temperate strain (V31.2) with an optimum temperature of growth, sporulation and aggressiveness to M. truncatula of 20°C and 25°C respectively. Since our strain collection doesn’t contain strains adapted to higher temperatures, we have obtained by UV mutagenesis of strain V31.2 a third strain (AS38), considered as a ‘hot’ strain, which is aggressive at 28°C. In the second part, we observed the symptoms of disease on seven natural accessions of M. truncatula, inoculated by the three strains of the pathogen at three temperatures 20°C, 25°C and 28°C in the presence of Sinorhizobium meliloti RCR2011. Mild symptoms were observed for two accessions A17 and DZA315.16 inoculated with VA1 at 20°C. We observed a maximal sensitivity for three accessions (F83005.5, DZA315.16 and L321) inoculated with V31.2 at 25 ° C, and for four accessions (F83005.5, DZA315.16, L321 and L198) inoculated with AS38 at 28 ° C. The results of phenotypic disease symptoms were confirmed by molecular quantification of fungal DNA (qPCR), and re-isolation of the fungus from aerial plant tissues. The effect of strains VA1 and V31.2 on three fitness traits (number and weight of pods per plant and aerial biomass) was studied. The effect negative of VA1 was observed only at 20°C on the A17 accession. In contrast, V31.2 showed an impact on the three fitness traits, which decrease in susceptible accessions, as well as on pod number of the resistant accession L198. In the third part, a similar analysis was made for four nodulation mutants in A17 genetic background. Nodulation mutants showed a higher level of resistance to VA1 than A17, at different studied temperatures. Towards strain V31.2 at 20°C the mutants skl and hcl showed the same symptom scores as A17 whereas nfp and sunn mutants had more susceptible. Mutants showed a higher sensitivity at 25°C to V31.2 fungal strain. The results of phenotypic disease symptoms were confirmed by re-isolation experiments. For the nodulation mutants we showed, for the first time, that only the sunn mutant (hypernodulant) has the same productivity as A17, regardless of the condition (inoculated or control) and the studied strain (VA1 or V31.2); while the skl mutant (hypernodulant also) has a lower productivity. The other two mutants defective in nodulation (nfp and hcl) showed lower productivity than A17 regardless of the strain (VA1 or V31.2) and the temperature studied. Finally, a strong similarity was found between the early phenotypic response symptoms disease in M. truncatula and M. sativa inoculated by Verticillium spp. In this thesis, we didn’t find a positive correlation between the ability of nodulation and protection against the disease, however the symbiosis increases the fitness of some of these plants. The results also suggest that increasing temperatures could favour appearance a strain adapted to 28°C (AS38), which is more aggressive and more virulent than V31.2 on M. truncatula
Jalbert, Jonathan. „Développement d'un modèle statistique non stationnaire et régional pour les précipitations extrêmes simulées par un modèle numérique de climat“. Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAU032/document.
Der volle Inhalt der QuellePrecipitation extremes plays a major role in flooding events and their occurrence as well as their intensity are expected to increase. It is therefore important to anticipate the impacts of such an increase to ensure the public safety and the infrastructure sustainability. Since climate models are the only tools for providing quantitative projections of precipitation, flood risk management for the future climate may be based on their simulations. Most of the time, the Extreme value theory is used to estimate the extreme precipitations from a climate simulation, such as the T-year return levels. The variance of the estimations are generally large notably because the sample size of the maxima series are short. Such variance could have a significant impact for flood risk management. It is therefore relevant to reduce the estimation variance of simulated return levels. For this purpose, the aim of this paper is to develop a non-stationary and regional statistical model especially suited for climate models that estimates precipitation extremes. At first, the non-stationarity is removed by a preprocessing approach. Thereafter, the spatial correlation is modeled by a Bayesian hierarchical model including an intrinsic Gaussian Markov random field. The model has been used to estimate the 100-year return levels over North America from a simulation by the Canadian Regional Climate Model. The results show a large estimation variance reduction when using the regional model
Charru, Marie. „LA PRODUCTIVITÉ FORESTIÈRE DANS UN ENVIRONNEMENT CHANGEANT : CARACTÉRISATION MULTI-ÉCHELLE DE SES VARIATIONS RÉCENTES À PARTIR DES DONNÉES DE L’INVENTAIRE FORESTIER NATIONAL (IFN) ET INTERPRÉTATION ENVIRONNEMENTALE“. Thesis, Paris, AgroParisTech, 2012. http://www.theses.fr/2012AGPT0027/document.
Der volle Inhalt der QuelleGrowth trends have been reported in many regions of Europe over the twentieth century. However, an integrated assessment of productivity changes, including focus on a wide geographical scale, analysis of spatial heterogeneity, and the inter-specific diversity of growth responses is still lacking. The aim of this Ph.D work was to assess recent changes in forest productivity on a national, regional and local scale in France, and to investigate their potential environmental causes, based on statistical modeling approaches of stand basal area increment (BAI), and environmental indicators. We used the French NFI data for 8 species of contrasted ecological niches and distributions (Fagus sylvatica, Quercus robur, Quercus petraea, Quercus pubescens, Picea abies, Abies alba, Pinus sylvestris and Pinus halepensis), taken in pure and even-aged stands. We identified the main factors influencing tree species productivity on a national scale, and produced productivity maps suggesting that species distribution ranges are not always limited by environmental conditions. Between 1980 and 2005, the productivity trends reported were positive, modal or non-significant for all species, except the two Mediterranean species for which productivity decreased, highlighting inter-specific differences in these changes. We observed strong variations of productivity changes, both in intensity and sign, on a regional and intra-regional scale. These results question the relevance of wide-scale average assessments and highlight their context-dependence. The role of recent climatic warming in featuring the BAI trends was highlighted. This work provides an enriched scale- and species-dependent assessment of tree species reaction to a changing environment. We emphasized the species- and context dependence of productivity changes, due to differences in species autecology and spatial variations in the limiting factors. Further focus on the effect of environmental factors and their complex interactions is needed for the prediction of species future productivity
Brouard, Yoann. „Caractérisation et optimisation d'un composite biosource pour l'habitat“. Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4024.
Der volle Inhalt der QuelleThe purpose of this study was to compare hygrothermal acoustical and mechanical properties ot different materials based on vegetal aggregates and clay in order to characterize the performances of different biocomposites to provide building insulation solutions with a view to valorizing agricultural waste. We first analyzed the raw materials in order to get the density, thermal and hydric properties of the vegetal aggregates in one hand and the mineralogy and gravimetric data of the selected crude earth in the other hand. Thermal behavior of earth:vegetal aggregates mixes have been investigated at different humidity rates and different density ranges. Additionally, hydric properties have been measured to produce sorption and desorption curves and moisture buffer values (MBV) in one hand and capillarity of both aggregates and biocomposites on the other hand. One of the main interests of this study is to confirm that a wide range of locally produced vegetal byproducts could be used as - bioaggregates for concretes. Local biomaterials industries could therefore emerge depending on the locally available resources at country scale
Gourde, Karine. „Le droit à un environnement de qualité au Québec : une réponse aux problèmes de pollution diffuse?“ Thèse, 2010. http://hdl.handle.net/1866/4794.
Der volle Inhalt der QuelleThe quality of the environment has become a growing concern in the recent years for Quebec citizens. Phenomena such as climate change, persistent organic pollutants and the depletion of the ozone layer are caused by several sources, the effects of which cannot be distinguished one from the other and/or linked to a specific event. Furthermore, these phenomena have yet to create damage to Quebec residents in order to create the necessary standing for the introduction of legal proceedings. Also, the scientific uncertainty related to the source of potential damage and to the proof of said damage makes it impossible to legally attack the emitters of the pollutant contributing to this type of environmental phenomena under 1457 C.C.Q. or 976 C.C.Q. We have identified the 3 potential sources of a right to a clean environment which could entitle Quebec citizens to go before the courts in environmental matters, even in the absence of specific damages to their person or property. We have analysed the Canadian Charter of Rights and Freedoms, the Charter of Human Rights and Freedoms and the Environmental Quality Act and looked at the potential right to a clean environment possibly contained therein and the legal actions that could be taken to ensure their respect. Considering the weakness of what our legal system had to propose, we have developed solutions that could be put forward in order to allow the war against climate change and other environmental phenomena of the same nature to become legally actionable.