Teses / dissertações sobre o tema "Phénologie – Effets des conditions météorologiques"
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Goutte, Aurélie. "Mécanismes hormonaux impliqués dans la phénologie de la reproduction chez les oiseaux marins polaires". Phd thesis, Université de Poitiers, 2010. http://tel.archives-ouvertes.fr/tel-00575409.
Texto completo da fonteLheureux, Edel. "Investigating Atlantic salmon (Salmo salar ) migration phenology using a long-term capture-recapture study : disentangling observation process from underlying ecological mechanisms using a Bayesian modelling approach". Electronic Thesis or Diss., Pau, 2024. http://www.theses.fr/2024PAUU3028.
Texto completo da fonteHuman activities are at the root of an unprecedented biodiversity crisis. Migratoryspecies are particularly at risk, because migration is risky and makesthese species dependent on multiple environments and their connectivity. Phenology,i.e. the timing at which a species completes an event of its life cycle,has a strong influence on the overall cost of that event. In this thesis, I focuson the phenology of the first seaward migration of Atlantic salmon (Salmosalar, A. salmon), a crucial event in its life cycle. Climate change is increasing lydisrupting the phenology of many species, including migratory species. Inparticular, it is altering the life-history traits and environmental cues that triggermigration. This can result in asynchrony between the conditions required by the species during, or following, the migration in question. Understandingthe mechanisms underlying phenological changes is essential for predicting theimpact that these disturbances could have on species. However, these mechanismsremain poorly understood due to incomplete data and/or inadequateapproaches to their statistical analysis. To study the first seaward migration ofA. salmon, I used long-term (25 years) mark-recapture monitoring in the Scorffriver (Brittany, France). Data collected in the natural environment are subjectto variations in the observation process that can mask or bias our understandingof the underlying biological processes. This is particularly important whenan environmental factor (such as flow rate) influences both the observation (forexample, the effectiveness of a trap) and the biological process (triggering ofmigration). To avoid misinterpretations, I propose a hierarchical, mechanisticBayesian modelling approach that explicitly separates the observation process(capture efficiency) and the dynamic process of interest (migration phenology),both of which are influenced by different effects of environmental factors. Afirst model provides an estimate of capture probabilities and their variationsover time, which are then used in a second model to identify the mechanisms ofmigration phenology. This second model highlights the importance of temperature,discharge and discharge variation in the migration decision. These factorsmay be disrupted by climate change, so I conclude by exploring the possibleconsequences of climate change on the phenology and size of young salmonduring their migration to the sea, both of which are crucial to their fitness. Mythesis highlights the importance of mechanistic modelling in understandingchanges in phenology, and offers an additional perspective for understandingthe ongoing decline in Atlantic salmon populations
Maignan, Fabienne. "Télédétection des surfaces continantales : correction des signatures directionnelles et suivi phénologique". Versailles-St Quentin en Yvelines, 2011. http://www.theses.fr/2011VERS0004.
Texto completo da fonteThe land surface component of the carbon cycle exhibits a large geographical disparity as well as a large interannual variability. It is important to survey and also to try predicting the evolution of this sink in response to climate change and human activities. A good knowledge of the physics of the satellite measurement allows us to model the land surface directional effects and thus to remove them from the measurement. We then construct less noisy time series of vegetation indices over almost three decades, from which we extract phenological parameters, phenology being the study of key-stages of the vegetal annual cycle in relation to climate. These satellite data may also be used for global vegetation models: to validate the modeled Leaf Area Index; to be assimilated and thus help improve the carbon fluxes budget; to calibrate phenological models
Dantec, Cécile. "Caractérisation des contraintes biotiques et abiotiques sur la phénologie printanière du chêne : expliquer les patrons de diversité et prédire les changements futurs". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0042/document.
Texto completo da fonteBudburst phenology is a major adaptive trait of trees to the environment in temperateclimate. Our aim was to characterize the biotic (powdery mildew) and abiotic (winter and springtemperatures / spring frost) constraints acting on budburst in view to explain the patterns of intra and interpopulations’ phenological variation observed in sessile oak (Quercus petraea) along an elevation gradient.We based our approach on in situ monitoring, experimentation and modeling. Our results highlight that theavoidance of late spring frosts is a major adaptive trait along the elevation gradient. The lateness inbudburst might be due to higher requirements in forcing temperatures. Otherwise, the fungus is not locallyadapted to its host phenology so oak individuals and populations are unequally exposed to the disease.With increasing elevation, oaks are more and more exposed to the fungus, but the environmental factorsare unfavorable to higher infection. At low elevation, powdery mildew and late spring frosts favor oppositephonological phenotypes (early-flushing vs. late-flushing trees, respectively); the combination of the twopressures may thus contribute to the maintenance of the observed high phenological diversity. We alsoshowed that powdery mildew infection induced an increased polycyclism during the growing season in oakseedlings, which made them less resistant to winter frosts. Predictive phenological models will have toinclude the chilling phase which conditions dormancy breaking. Although the lack of chilling is not yet alimiting factor, the current trend in increasingly advanced budburst will certainly be slowed or even reversedin the middle of the century at low elevation, in the southern margin of the distribution area of Q. petraea
Leclercq, Nicolas. "Influence de l'augmentation de la pression partielle de co 2 sur le metabolisme des coraux et des communautes recifales : approche experimentale". Paris 11, 2000. http://www.theses.fr/2000PA112036.
Texto completo da fonteBouilloud, Ludovic. "Modélisation des caractéristiques de surface d’une chaussée en condition hivernale en fonction des conditions météorologiques". Toulouse 3, 2006. http://www.theses.fr/2006TOU30250.
Texto completo da fonteDuring winter, ice or snow presence on the road might have serious consequences on road traffic. To develop a decision-making tool for road management in winter, a numerical model which permits to simulate snow behaviour on roads was developed. It results from the coupling of the ISBA and CROCUS models, which are respectively the soil and snow model of Météo-France. This model was validated thanks to observed snow on road events, resulting from a previous experimental field campaign led on the Météo-France experimental station located at the Col de Porte (1320m, Isère). The validation was first done with the meteorological data measured on the site, and then with forecasted data. Results of the forecast on the experimental site were satisfactory, so the model was spatialized at the France scale, with a 8km grid resolution. The 2004/05 winter, with many snow on road events, was simulated. The validation was done thanks to road station data from several Highways and thanks to measurement from the Météo-France stations network
Qabil, Saïd. "Evolution des aérosols atmosphériques et conditions météorologiques en région bordelaise : études par spectrométrie de vibration". Bordeaux 1, 1988. http://www.theses.fr/1988BOR10552.
Texto completo da fontePremat, Eric. "Prise en compte d'effets météorologiques dans une méthode d'éléments finis de frontière". Lyon, INSA, 2000. http://theses.insa-lyon.fr/publication/2000ISAL0039/these.pdf.
Texto completo da fonteIn environmental acoustics there is today a need for models to predict sound propagation at long ranges. Meteorological effects become then important. This work aimed to develop a model for complex atmospheric sound propagation above uneven absorbing grounds. We have derived a new model : Meteo-BEM, based on one hand on the boundary element method, that allows the assessment of any kind of shape and absorption of the propagation-domain, and on the other hand on recent propagation models in inhomogeneous media. The formulation relies on the layer potentials theory. The Green's function used is based on the normal modes solution for downward refraction, and in the case of upward refraction, on the residue series solution in the shadow zone and on the geometrical model in the illuminated region. In order to illustrate this new approach, the case of a thin rigid screen, on a reflecting and on an absorbing ground, is studied, under various refracting conditions. The model is first compared for validation to numerical and experimental results coming from the literature. Then measurements undertaken in laboratory above curved surfaces are presented. The good agreement between calculated and measured datas for downward refraction shows that meteorological effects can be included in a boundary element method
Guillemette, Simon. "Effets du climat et des conditions météorologiques locales sur les changements de masse saisonniers du mouflon d'Amérique (Ovis Canadensis)". Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/9520.
Texto completo da fonteLe, Provost Grégoire. "Effet de la saison et d'un stress mécanique sur la variation du transcriptome dans le xylème en formation chez le pin maritime (Pinus pinaster Ait. )". Bordeaux 1, 2003. http://www.theses.fr/2003BOR12675.
Texto completo da fonteLeriche, Pierre. "Les situations météorologiques associées aux épisodes de pollution atmosphérique dans la région lilloise". Lille 1, 2003. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/ae7b1b5d-3c24-42b7-842e-8f5e260da440.
Texto completo da fonteLaaidi, Mohamed. "Contribution à l'étude aéropollinique de la Haute-Bourgogne : introduction à une géographie des risques allergéniques". Dijon, 1999. http://www.theses.fr/1999DIJOMU08.
Texto completo da fonteHalf the allergic diseases are due to anemophilous pollen, wich represents a prevalence of 10% among the french population. So we wished to realise in this research a quite complete study of aeropalynology problems in Upper Burgundy. This induced us to set up three traps in Montbard, Dijon and Mâcon, and to use a fourth one already set up in Chalon-sur-Saône. Their results allowed us to list all the anemophilous pollens of the region, and to establish pollen calendars for each site. Then we compared pollinic counts and concomitant meteorological data, which showed the influence of rainfall, temperatures relative humidity, sunshine wind and atmospheric pressure on the release and scattering of the pollen in the air. But pollen collections vary substantially in space and time ; thi lead us to develop forecasting methods using meteorological parameters prevaling before flowering. These were applied to birch (Betula) and grasses (Poaceæ), which are the two most allergenic taxa in the region. Thus could be predicted the onset and duration of pollination, and there's no point in emphasizing how useful such data are for allergists and allergic people , so long as they are available beforehand enough
Maksimovich, Elena. "L' impact des conditions météorologiques sur la variabilité de démarrage de la fonte sur la glace de mer en Arctique centrale". Paris 6, 2012. http://www.theses.fr/2012PA066033.
Texto completo da fonteTiming of spring Snow Melt Onset (SMO) on Arctic sea ice strongly affects the heat accumulation in snow and ice during the short melt season. This summertime heat uptake is quasi-linearly and inversely proportional to the remnant ice volume by the end of the melt season. On top of sea ice SMO timing, as well as its interannual and regional variations are controlled by surface heat fluxes. Anomalously early (delayed) SMO is due to large and early (weak and retarded) heat accumulation within the snowpack. Satellite passive microwave (SSM/I) observations show that the \textit{apparent} Melt Onset (MO) varies by 20-30 days interannually and over 25-50 km distance. These apparent MO records appear to be a complex blend of SMO on sea ice and sea ice opening due to divergent ice drift. We extracted SMO out of the apparent MO record using sea ice concentration data. Applying 20-year ERA Interim reanalysis of radiative and turbulent surface heat fluxes we examined how well the heat fluxes reflect the variations in SMO. Anomalies of heat fluxes in the pre-melt period explained a significant portion of the interannual and spatial variations in SMO within the central Arctic. The main term was the downward longwave radiation locally accounting for up to 90\% of the temporal SMO variations. The role of the latent and sensible heat fluxes in earlier/later SMO was not to bring more/less heat to the surface but to reduce/enhance the surface heat loss. Solar radiation alone was not an important factor for SMO timing. Anomalies in surface fluxes were examined also in relation to meteorological conditions. 20-year MO and SMO trends are towards earlier spring melt in the central Arctic Ocean
Palluau, Fabienne. "Mise au point et optimisation des techniques de prélèvement et d'analyse des composés organiques volatils (COV) dans l'atmosphère : Etude de l'influence de facteurs climatiques et de l'ozone sur les teneurs mesurées en COV". Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13162.
Texto completo da fonteUllmann, Albin. "Surcotes dans le Golfe du Lion et conditions atmosphériques : variabilité contemporaine et future (1905-2100)". Aix-Marseille 1, 2008. https://tel.archives-ouvertes.fr/tel-00305449.
Texto completo da fonteDelattre, Thomas. "Influence de la structure du paysage et des conditions météorologiques sur le comportement de dispersion de Maniola jurtina (Lepidoptera : Nymphalidae, L. ) dans un agroécosystème bocager". Rennes 1, 2010. http://www.theses.fr/2010REN1S217.
Texto completo da fonteDispersal is the movement of individuals with potential consequences on gene flow. The distribution patterns of metapopulations and communities in the landscapes result from the inter and intra-individual variations of dispersal. The selection pressures due to human-driven landscape changes cause the apparition of specific movement strategies, with a growing contrast between strategies adapted to resource searching inside patches, and patch searching inside landscapes. The quantitative analysis of M. Jurtina dispersal behaviour allowed us to highlight a strategy adapted to long distance dispersal, the “direct moves”, which is different from the “foray loops” strategy that was known for this species, and is adapted to local short-distance exploration. Besides, in ectotherms activity is strongly dependant on meteorological conditions. We showed that this effect applies to dispersal too, that the dispersal strategies of M. Jurtina are differently affected, and that it changes the functional connectivity at the landscape scale. Moreover, we examined the dispersal behaviour of M. Jurtina along a gradient of agricultural intensification, and showed how dispersal is affected by habitat loss and environmental stochasticity. Finally, we estimated the potential corridor role of an agri-environment scheme set up in European landscapes: the grassy field margins. We used a combination of individual-based simulations of movement, and field surveys of movement inside grassy field margins and habitat patches to estimate this corridor function
Versini, Pierre-Antoine. "Surveillance du risque hydrologique diffus le long des itinéraires routiers : éléments pour la construction d'un outil d'annonce de coupure". Marne-la-vallée, ENPC, 2007. http://www.theses.fr/2007ENPC0736.
Texto completo da fonteGicquel, Aurélien. "Impact des changements globaux sur le fonctionnement des tourbières : couplage C-N-S et interactions biotiques". Rennes 1, 2012. https://ecm.univ-rennes1.fr/nuxeo/site/esupversions/fc809707-f62e-4b7b-aaa0-3ce961750dde.
Texto completo da fonteIn a context of global change, peatlands "sink" function of carbon (C) is likely to switch to a "source" function, releasing into the atmosphere large quantities of C initially stored in the peat. This thesis aims to characterize and quantify at different levels of organization: i) the impact of global warming on Sphagnum-peatland biogeochemical functioning (CNS) and ii) the impact of restoration of peatland abandoned after harvesting of peat on the interactions between recolonizing plants (Eriophorum angustifolium), macrofauna (Lumbricus rubellus) and the microorganisms potentially involved in the regeneration process of peat forming. The peatland functioning and biotic interactions have been studied by coupling C-N-S and isotope tracing 13C-15N-34S. A moderate increase of + 1°C simulated by "Open Top Chambers" (OTCs) significantly reduces C fluxes at the ecosystem level, the primary production of Sphagnum and the microbes are most affected. At the community level, the activity of anaerobic bacteria, fungi and protozoa (estimated by SIP 13C-PLFAs) was significantly slowed. We showed that a soil engineer as the earthworm L. Rubellus played a positive role in recycling organic matter indirectly by providing elements (C > N > S) to the plant. Transfers depend on the functional traits of the organism. At the individual level, we have characterized using NanoSIMS, "anticorrelated" NS transfers from earthworms to peat
Castaing, Laurent. "Hibernation et reproduction du hérisson (erinaceus europaeus L. ) : interrelations et régulation par les facteurs externes". Tours, 1985. http://www.theses.fr/1985TOUR4008.
Texto completo da fonteMontmayeur, Alain. "Sommeil humain au Sahel chez des sujets mélanoïdes et caucasiens : effets de la saison et de l'activité physique". Lyon 1, 1994. http://www.theses.fr/1994LYO1T108.
Texto completo da fonteRouspard, Pierre. "Etude phénoménologique du dépôt sec d’aérosols en milieu urbain : Influence des propriétés des surfaces, de la turbulence et des conditions météorologiques". Thesis, Rouen, INSA, 2013. http://www.theses.fr/2013ISAM0007/document.
Texto completo da fonteAerosol dry deposition is not much known for urban areas due to the lack of data. Knowledge on this phenomenon is necessary to understand pollutant fluxes in cities and to estimate inhabitant exposition to ionizing radiation of radioactive aerosols. A data providing could enable to enhance dry deposition models for these areas. An original experimental approach is performed to study submicron aerosol dry deposition on urban surfaces. Wind tunnel coupled to in situ experiments give results to study different physical phenomen on governing dry deposition. Dry deposition velocities are measured using aerosol tracers. These data are associated to turbulent and meteorological measured conditions. This database permits to classify the principal physical phenomenon for each experiment type. Finally, different phenomenon must be considered for chronic and acute exposition of urban surfaces to atmospheric particles
Bonelli, Stefano. "Impact des variations de l'insolation et du CO2 atmosphérique sur l'évolution passée et future des calottes de glace". Versailles-St Quentin en Yvelines, 2009. http://www.theses.fr/2009VERS0054.
Texto completo da fonteBetter understanding the Earth’s climate system is a major issue for the scientific community. The climate system is characterized by a high degree of complexity, due to the numerous interactions between its various components (i. E. Atmosphere, oceans, biosphere, lithosphere and cryosphere), operating at different timescales. Furthermore, the anthropogenic pressure has also to be considered in a comprehensive description of the climate system, since it is capable of modifying its state, as well as the amplitude and frequency of the natural variability. The study of past climatic variations represents a primary means to understand the ongoing climate change: on the one hand, it allows direct comparison with previous warm episodes, and, on the other, it is useful to validate climate models for paleo-climatic conditions fully different from the present day ones, yet well-constrained by data-sets. Indeed, the Earth’s climate has always been characterized by changes; the transitions between “cold” states (glacial periods) and “warm” ones (interglacials), and vice versa, have been a major feature of the system for the last three million years. These changes are better known as glacial-interglacial cycles, and their existence is recorded in many climatic archives (i. E. Sea sediments, ice cores, continental records). The main goal of this thesis is to better understand the transition from interglacial periods to glacial ones for different timescales (geological timescale, Milankovitch timescale and future projections), by using a fully coupled climate-ice sheet model. Our work represents a step forward in the study of “low frequency” climate variability. We have tested the model performances for three different case studies, corresponding to different periods of the Earth’s history. The first part of this thesis is focused on the study of the Cenozoic glaciation of Antarctica, which enables us to pinpoint the complex links between atmospheric CO2 concentration, tectonics (i. E. The opening of the Drake Passage), global climate and the inception of the Antarctic ice sheet 34 Ma ago. The second part deals with climate-ice sheets interactions at the Milankovitch timescale, and provides a “transient” simulation of the last glacial-interglacial cycle. Finally, the third part is dedicated to the future ice sheet evolution, focusing on the next glacial inception, and on how this transition might be affected by anthropogenic activity. Our approach covers the range of applicability of the coupled model, thus highlighting its strengths, but also its major limitations, and offers new insights for the ongoing studies on the links between climate and ice sheets
Peultier-Celli, Laetitia. "Facteurs prédictifs de la qualité du contrôle postural et de sa compensation dans les pathologies traumatiques et dégénératives du genou". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0150/document.
Texto completo da fonteThe knee can suffer damage from either traumatic or degenerative pathology. Anterior cruciate ligament (ACL) injuries frequently occur, especially in activities that including rotational stresses. Degeneration of the articular cartilage of the knee can subsequently result in osteoarthritis. The aim of this study was to analyze the predictive factors of postural control and recovery in traumatic injuries and also in degenerative pathologies of the knee. The effects of an innovative rehabilitation protocol combining reduced conventional rehabilitation with aquatic rehabilitation were compared with conventional rehabilitation defined by the National French Health Authority on the kinetics of recovery of proprioceptive skills and functional improvement. Postural control and motor control using clinical tests were quantified in 67 patients with ACL surgery before and up to six months after surgery. The effects of meteorological parameters on postural control and pain in knee osteoarthritis were evaluated in 113 patients, using posturography and also a pain scale. Six months after knee ligament surgery, both groups attained the same quality of postural control. However, patients who followed the innovative protocol made more used of proprioceptive inputs compared to the group who underwent conventional rehabilitation who made more use of a compensation mechanism. In patients following the innovative protocol proprioception was improved two months after surgery compared to before surgery. Muscle strength was higher in patients who followed the innovative rehabilitation protocol at one, two and six months after surgery. One month after surgery, the walking distance traveled was higher in patients who underwent innovative rehabilitation than in patients who had undergone conventional rehabilitation. In patients with knee osteoarthritis, degradation of postural control was observed when atmospheric pressure and maximum humidity decreased during the morning and when atmospheric pressure decreased during the entire day. Increased pain was correlated with increased temperature in the morning and with increased temperature and humidity during the entire day. The environment in which evolves the subject (aquatic, climatic) thus has an influence on postural control performance. A better management in post-ligamentoplasty rehabilitation of the knee would reduce the need for compensation using the contralateral limb, by better use of somesthesia. This could prevent the occurrence of osteoarthritis and a contralateral ACL injury, which would also reduce costs to the society and health care
Stéfanon, Marc Alexandre. "Canicules et sécheresses en Méditerranée : contributions des processus couplés surface-atmosphère à méso-échelle". Palaiseau, Ecole polytechnique, 2012. https://pastel.hal.science/docs/00/74/71/24/PDF/TheseStefanon.pdf.
Texto completo da fonteIn a context defined as that of global warming, with fears that one summer out of two could be very similar to the 2003 European heat wave, the significant role played by droughts and land-atmosphere coupling in the enhanced and persistent high temperatures during heat-wave events has been highlighted by various studies. I have developed an original classification based on the spatial structures of the heat waves ocurring in the Euro-Mediterranean area. Classification are generally designed to classify numerous events, so we have had to adapt to classifying rare events, by introducing three criteria grounded on temperature and the spatio-temporal extension of the phenomena to be described. The classification has enabled us to sort out six different categories of heat wave. In course of the investigation, I then proceeded to focus on one of the categories, id est on Westen Europe heat wave. I carried out numerical sensitivity tests in order to analyse how the hydric deficit of soils contributes to amplifying heat waves and was able to bring out different behaviours. In the continental plains, the atmospheric boundary layer temperatures are largely controlled by local dry convection processes. In the mountainous and coastal areas, mesoscale circulations such as slope winds and sea breezes contribute to mitigating heat waves by allowing fresh and moist air to advect and precipitations to form. The effect of vegetation on heat waves was also examined. To do so, I have developed modelling tools which couple atmospheric dynamics with vegetative dynamics and thus present an innovative view on heatwave and drought conditioning processes in Western Europe. This modelling development is part of a larger project that aims at developing a model for regional climatic system and which has been undertaken at the Institut Pierre Simon Laplace (IPSL) as part of the MORCE-MED project. This question has so far been little addressed in the scientific literature. I have shown that the inclusion of an interactive vegetation into modelling enable to simulate the modifications of the phenological cycle that control plant growth and development as well as evapotranspiration. Used to analyse the heat waves of June and August 2003, I have been able to demonstrate that the interaction of vegetation had a mitigating effect on the June 2003 heat wave, while it had a reversed effect in August, id est that of reinforcing. Lastly, we have measured the effects of land cover change that would allow to mitigate the consequences of heat waves on humans. In a preliminary study, I replaced anthropized surfaces (mainly agricultural land) by forests and meadows. There again, the effects noted were more contrasted than expected and presented a mitigation of the heat in June and an increase in the temperatures in August, with a high spatial variability on a mesoscale
Joannin, Sébastien. "Changements climatiques en Méditerranée à la transition Pléisctocène inférieur-moyen : pollens, isotopes stables et cyclostratigraphie". Lyon 1, 2007. https://tel.archives-ouvertes.fr/tel-00347549.
Texto completo da fontePollen analysis has been performed on six sections (Santa Lucia, Montalbano Jonico, Site ODP 976; Tsampika and Shamb) placed along a 4,000 km long transect from the Western Mediterranean region to Little Caucasus. These sections recorded same vegetation changes related to climatic cycles occurred throughout the Mediterranean region during the Early-Middle Pleistocene (1. 600-0. 700 Ma), despite an observed longitudinal gradient. Mesothermic taxa were affected by the increasing aridity and the extremes related to climatic cycles during this considered time-window. “Long-term” vegetation successions were controlled by climatic cycles related to the obliquity forcing. A similar vegetation dynamics with short and longer-term durations were forced by precession and its modulator (the eccentricity), respectively. Influences of both parameters were superimposed. The expected shift from obliquity to 100 ka long-cycles related to eccentricity is not observed in the Mediterranean region during the Mid-Pleistocene Transition
Boucher, Laurence. "Le spermatophore chez caryedon serratus 01. (coléoptère bruchidae) : conditions de formation, évolution et influence sur l'activité reproductrice des femelles". Tours, 1987. http://www.theses.fr/1987TOUR4002.
Texto completo da fonteDufour, Florence. "Méta-analyse des effets de l’environnement sur la dynamique des stocks de thonidés". Pau, 2010. http://www.theses.fr/2010PAUU3029.
Texto completo da fonteClimate change may affect spatial and temporal distribution of tuna species due to its impact on lower trophic levels. Hence, the aims of this thesis are (1) to determine the main environmental variables that define tuna habitat (2) to define the ranges of preference, tolerance and avoidance for these variables and (3) to study, at different scales, the effect of environment on spatiotemporal distribution of tuna and billfish of the Atlantic. Generalized additive models (GAM) were carried out to determine the environmental variables defining global tuna habitat. For each species the best model included all environmental variables considered i. E. Temperature, salinity, dissolved oxygen, sea level anomaly, mixed layer depth and chlorophyll. GAMs revealed that for most species surface temperature, dissolved oxygen and sea level anomaly were variables explaining most of CPUE deviance. Besides, the quotient analysis was used to define tuna ranges of preference, tolerance and avoidance for different environmental variables. It appeared that tropical species prefer warmer, less productive, and more oxygenated waters than temperate species. The second part of this thesis revealed that albacore and bluefin tuna seasonal movements to the Bay of Biscay appeared earlier in the 2000s than in the 1960s and 1980s, respectively. The rate of change was 2 and 5. 6 days for decade, respectively. This change was correlated with phenological changes in temperature over the same periods. Moreover, the temperature, latitude of 17 °C isotherm in particular, also showed a correlation with albacore catch latitude in adjacent waters of the Bay of Biscay. It also moved 2. 5 ° northwards over the last 40 years. Lastly, we showed that the late 1980s regime shift of the North Atlantic had an influence on the migration of these two species. Finally, a synthesis of all local studies on tuna and billfish in North and South Atlantic was addressed in a meta-analytic framework. The overall result indicates that species distribution do not correlate with temperature. However, the overall correlation was positive in the northern hemisphere. Species catch latitude showed stronger correlations with the North Atlantic Oscillation and the Southern Oscillation than with temperature. These different results suggest that temperatures could be a factor determining species local distribution whereas some ocean physical processes should be considered in order to understand tuna spatial dynamics across oceans
Pierret, Pauline. "Devine qui vient dîner … : graines des villes et graines des champs, ou l'impact de l'agriculture péri-urbaine sur les oiseaux des jardins". Thesis, Paris, Muséum national d'histoire naturelle, 2018. http://www.theses.fr/2018MNHN0003/document.
Texto completo da fonteSupplementary feeding of wild birds in private backyards is a globally widespread pastime. It provides a wonderful opportunity for research and survey of winter bird populations at spatial and temporal large-scales by involving householders in citizen science programs. We used data from the French national garden birdwatch scheme, a citizen science program operated by the Ligue de Protection des Oiseaux, to study winter bird abundance variations in gardens which provided food supply, at a large spatial scale. This thesis aims to understand which factors influence the visit of gardens by birds during winter, a season traditionally pointed out to have the greatest impact on passerine survival. We highlighted that gardens with feeders located close to intensively cultivated farmland attract birds as a response of the countryside natural resource scarcity leads by intensive agricultural practices. This relationship being stronger for farmland seedeater species. Variations in the use of garden by birds also fluctuate between years and with weather conditions, but the variations were not similar among species. This being consistent with the expected influence of their ecological and biological differences. This garden bird survey in winter also reflected the global negative trends observed for some granivorous species in France or Europe during the breeding season, confirming that the use of garden bird feeders by wild bird species offers a new tool to survey the global population trends. We also suspect that variation in abundance could mirror spatial differences, and maybe mirror human activities impacts such as poaching, but this part requires further investigation. Finally, our work could be beneficial for maintaining declining seedeater species, by advising to supply birds with winter food in garden located in intensive agricultural landscape, while continuing to engage the public with nature
Musereau, Jonathan. "Approche de la gestion des cordons littoraux : mise au point et application d’un indice d’érosion (Zone des Pertuis Charentais, France)". Rennes 2, 2009. http://tel.archives-ouvertes.fr/tel-00422116/fr/.
Texto completo da fonteMany coastal morphodynamics studies assume that environments are natural and that natural equilibriums are sometimes modified by human interventions, and are therefore studied as such. In this Ph D. , a different approach is developed, namely the description of behaviours of “artificial” coastal features forced by actual climatic conditions. In “la Zone des Pertuis Charentais”, three sites, where past interactions between natural and anthropogenic processes resulted on a historical seaward progression of the coastline, were selected: the lagoon of La Belle-Henriette, the coastal dune of Saint-Trojan and the beach of Marennes. On these sites, present environmental evolution induces strong erosion, notably during storms events. Local coastal managers call out to the relevancy of methods used for the prediction of such hazards, because of their practical limitations. To answer this social demand, a simple formulated storm index, locally tuned and freely implemented, was developed. The method has been tested using an archive dataset (from 1999 to 2009) and proved to be successful for predicting erosion events (numerous cases in the recent years)
Guy, Sylvain. "Effet des faibles températures sur la nodulation et la photosynthèse des plantes fixatrices d'azote chez le soja (Glycine max L. Merr. )". Toulouse, INPT, 1995. http://www.theses.fr/1995INPT013A.
Texto completo da fonteCissé, Soukèye. "Etude de la variabilité intra saisonnière des précipitations au Sahel : impacts sur la végétation (cas du Ferlo au Sénégal)". Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066177.pdf.
Texto completo da fonteThe Sahel is characterized by a strong intra-seasonal variability of rainfall. This variability strongly affects ecosystems during the vegetation growth. The objective of this thesis is to characterize this variability at the local scale from the relationship between rainfall and vegetation dynamics, and to identify relevant indicators to better describe the variability in each season. This study is carried out in the Ferlo’s catchment, a basin located in northern Senegal. The first part is devoted to the characterization of the relationship between rainfall anomalies and growth of vegetation from remote sensing data TRMM3B42, RFE 2.0 SM-ECV (Soil Moisture) and MODIS LAI. Aiming that, the Ferlo basin is divided into 9 zones "homogeneous entity", in terms of vegetation cover class and soil type. For each one are analyzed the rain data from both databases, soil moisture and LAI over the period 2000-2010. In a second time, with a vegetation model adapted to the region forced by satellite rain fields, the LAI is simulated on several entities and is compared to the MODIS LAI, applying on the simulations the same methodologies as for observations. The results of this study show consistency between rainfall variations with both databases and soil moisture. The LAI variations are more strongly correlated with the soil moisture variations than with the rainfall. On the Ferlo, we observe that vegetation needs two weeks to respond to rainfall anomalies during the rainy season. At the season scale, the starting date of the rainy season does not affect the maximum LAI, unlike the duration and intensity of the dry spells. Entities located on sandy soil (ferruginous) have better sensitivity to rainfall fluctuations as those located on lithosoils. In addition, on entities located in the Southeast, the density of the shrub and tree vegetation induces a different phenological cycle than those of the herbaceous (lag of the maximum LAI). The model STEP, initialized with satellite rainfall data, reproduces after adjustment the vegetation growth stage in the entities where grassland dominates. The response of the simulated LAI to the rain anomalies is consistent with those observed, confirming the interpretation of observations. This study allowed to define the most relevant parameters that affect the dynamics of vegetation but also to highlight the capabilities of the model to describe the seasonal cycle of vegetation
Omari, Bachir el. "Régulation de la fonction de reproduction et de l'hibernation par les facteurs de l'environnement chez le hérisson (erinaceus europaeus l. ) : aspects neuroendocriniens et métaboliques". Tours, 1987. http://www.theses.fr/1987TOUR4011.
Texto completo da fonteMercier, Denis. "Le ruissellement au Spitsberg". Clermont-Ferrand 2, 1998. http://www.theses.fr/1998CLF20011.
Texto completo da fonteGoffart, Jeanne. "Impact de la variabilité des données météorologiques sur une maison basse consommation. Application des analyses de sensibilité pour les entrées temporelles". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00982150.
Texto completo da fontePellerin, Geoffrey. "Quantification des vitesses de dépôt par temps sec et documentation des processus d’émission des aérosols sur couvert naturel : du nanomètre au micron". Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1086/document.
Texto completo da fonteThe particles emitted into the atmosphere during chronic or accidental release by the nuclear plants can be subjected, after dispersion, to vertical flows by dry weather: dry deposition and resuspension. Vertical flows in dry weather are characterized by the vertical transfer rate, which is the ratio between the particle flux and the atmospheric concentration of the aerosol in the vicinity of the surface. When this speed is positive, it is a dry deposition rate (Vd in m.s-1) and conversely, when it is negative, it is a transmission rate. It is important to study their dry deposition in a prairial environment. Indeed, the products resulting from this environment are a component of the human food chain via livestock. For particles less than 1 μm, there is a lack of experimental data, which results in uncertainty about the results of the models, which can reach up to two orders of magnitude. In addition, there are no in situ deposition rate measurement data available for particles less than 10 nm. These particles are derived from the gas / particle conversion (nucleation) and may relate to certain radionuclides such as iodine (129, 131I).After their deposition, these radionuclides can be resuspended under the effect of the stress submitted by the wind on the canopy. Such a phenomenon is suspected around the Fukushima nuclear power plant. The aerosol resuspension processes are characterized by the vertical transfer rate (m.s-1) but also by the re-suspension coefficient (Ks in m-1) which is the ratio of atmospheric concentration to surface concentration of particles. Relative uncertainties of 2 to 3 orders of magnitude on the resuspension coefficients exist. The resuspension concerns all the particles present on the canopy, whether they are inert or living (fungi, bacteria, yeasts, etc.). Unlike inert particles, these living particles can assimilate and concentrate radionuclides. However, there is very little data on the resuspension of microorganisms and bacteria in particular. In this context, the objectives of the thesis are to quantify the dry deposition rate as a function of the particle size and the main micrometeorological parameters in the range 1.5 nm - 1.2 μm. The second objective is to document the processes of emission of the bacteria
Xiang, Yang. "Analyse dynamique en champ proche de la contribution des sources de composés organiques volatils, en région urbaine sous influence industrielle". Electronic Thesis or Diss., Littoral, 2011. http://www.theses.fr/2011DUNK0408.
Texto completo da fonteRecently, sources apportionment of Volatile Organic Compounds (VOC) has been the subject of a great numbers of studies, in order to determine their contributions to atmospheric pollution. However, the dynamical behavior of atmosphere, within its micro-meteorological scale, has never been taken into account in the sources-receptor approach, yet it is the main factor to interpret near-field physic-chemical measurements of air pollution, in an urban area under industrial influences. The complexity of such a study area results from not only the emission modes and the various industrial activities, but also the meteorological phenomenon in multi-scale, which influences the dispersion and transport in a small scale (tipically several kilometers). With measurements of 85 VOC (including 23 oxygenated VOC) during several months, we have developed an innovative methodology, associating the results of the PMF (Positive Matrix Factorization) modeling and the meteorological parameters, in order to identify the sources and to understand their dynamical behaviors. By introducing the vertical turbulence for the first time in this kind of analysis, the temperature and the solar radiation, as parameters of factor analyses, two behaviors have been distinguished, leading to identify the emissions near ground and in the upper part of surface layer. In this way, we have labeled the sources according to their nature as well as their emission mode, and we have highlighted the aged air mass containing secondary pollutants
Chaudhuri, Pritish. "Effect of variation in sunlight on the behaviour of stock analysts". Electronic Thesis or Diss., Aix-Marseille, 2021. http://www.theses.fr/2021AIXM0524.
Texto completo da fonteUsing Europe data over the 1999 to 2018, we find that analysts generally commit errors in the estimates during sunny days and sunny days are the proxies for positive mood. Further, in cloudy days, the estimates by the analysts are more accurate and cloudy days are proxies for negative mood. Moreover, the inaccuracy in analyst’s estimates changes due to additional factors like financial crisis period, star rating of the analyst and individualism which is a proxy for the cultural traits. In addition, we found that analyst’s estimates are positively biased in a sunny day which is a proxy for the happy mood and negatively biased in a cloudy day which is a proxy for the sad mood. Also, these biases change when additional factors like market cap, IBES recommendation score and uncertainty avoidance which is a proxy for cultural traits are added in the model. However, the inaccuracy and the biases do not change in case of male and female analysts. In fact, it effects at a subconscious level that is impossible for any analyst to realise. Overall, our results are consistent with the concept of cognitive stimulus conceived by mood of the analysts, who make less or more accurate estimates under the influence of positive or negative mindset due to variation in sunlight
Gicquel, Aurélien. "Impact des changements globaux sur le fonctionnement des tourbières : couplage C-N-S et interactions biotiques". Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00734604.
Texto completo da fonteKrayem, Ali. "Identification by inverse method of optical properties of a participating medium - Application to the impact of fog on artificial perception". Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2024. http://www.theses.fr/2024UCFA0023.
Texto completo da fonteOptical sensors (cameras, lidars, and radars) are commonly used for perception in automated vehicles. The primary function of these systems is to detect obstacles in order to avoid them. However, adverse weather conditions such as rain or fog can disrupt these information streams, impacting the performance and safety level of autonomous vehicles. The Cerema, through its "PAVIN Fog&Rain" platform, conducts evaluations of these sensors under controlled rain and fog conditions. In order to perform testing in a vitual environment allowing to consider a large variety of scenarios, what can be achieves by developing a digital twin of the platform, it is necessary to develop a robust model of electromagnetic wave propagation in fog whose outputs are close to experimental meaasurements made in the platform. To achieve this modeling, a thorough understanding of the fog droplet size distribution is required. In this thesis, we are devising a method to identify this distribution using radiance data measured in the Cerema's Rain&Fog PAVIN platform.In this work, radiance propagation modeling is based on the Lorenz-Mie theory. Our goal is to reconstruct the particle size distribution, denoted as N, by inversely solving the radiative transfer equation from radiation measurements at several wavelengths. This approach enables the identification of fog's optical characteristics through the evaluation of coefficients in the radiative transfer equation, including the extinction coefficient, absorption coefficient, scattering coefficient, and the phase function. Indeed, using the Lorenz-Mie theory allows to express these coefficients in terms of the distribution N. In our work, we focus on the 1D stationary radiative transfer equation, which has a unique solution satisfying certain estimates.In our study, we introduce a minimization problem with an objective function that enables the identification of the distribution N. This function quantifies the difference between measured and radiative transfer model-evaluated radiance, with the distribution N as input. We show that the objective function is continuous, differentiable, and strictly convex, ensuring a unique solution for the minimization problem. We then apply the Barzilai-Borwein algorithm to minimize this function by using a gradient descent based method to solve our minimization problem. Comparisons with other minimization algorithms, such as CG-Polak-Ribière and CG-Daniel, have been conducted. We approximate both the direct and adjoint problems using the double Legendre polynomial basis decomposition. Code validations have been performed using the explicit solutions provided by Dautray-Lions. Leveraging the Lorenz-Mie theory, we have formulated the inversion problem for the 1D case, validating against the explicit case (where the collision operator is null). Mathematical analysis of the problem subsequently yielded specific results.Optical characteristics of the medium are evaluated through the inversion of the radiative transfer equation, yielding numerical reconstruction results in various scenarios (direct measurements in front of the light source and inverse measurements of backward-diffused luminance). At present, the droplet size distribution has been reconstructed using synthetic measurements (model outputs) derived from a target granulometry distribution. Simulations have been performed using artificial fog droplet size distributions from the PAVIN platform at Cerema, natural distribution, and for distribution obtained from the theoretical model as Shettle-Fen.The identification results are obtained by using two different source types which are the Lambertian source and the Collimated source. For both source types, we obtained a good approximation of our DSDs. We also give numerical results of the DSDs identification in the anisotropic case with the Henyey-Greenstein phase function and we do not limit ourselves to the Lorenz-Mie phase function
Stieber, Pascale. "Approche d'une caractérisation simple de la pollution en hydrologie urbaine, à partir du couple temps sec/pluie". Vandoeuvre-les-Nancy, INPL, 1996. http://docnum.univ-lorraine.fr/public/INPL_T_1996_STIEBER_P.pdf.
Texto completo da fonteBhugwant, Chatrapatty. "Étude physico-chimique des aérosols de combustion et de l'ozone troposphérique à la Réunion". La Réunion, 2001. http://elgebar.univ-reunion.fr/login?url=http://thesesenligne.univ.run/01_16_Bhugwant.pdf.
Texto completo da fonteCécé, Raphaël. "Simulations numériques méso- et micro-échelles des circulations locales générées par des îles tropicales : cas de l’archipel de la Guadeloupe avec une application à la dispersion de polluants (WRF-LES-FLEXPART)". Thesis, Antilles-Guyane, 2014. http://www.theses.fr/2014AGUY0735/document.
Texto completo da fonteThe present work expresses the will of Caribbean researchers to improve the meso- and micro-meteorological scientific knowledge of the trade winds influenced island areas, and to develop research in these domains.It is well known that tropical hurricanes remain the most remarkable meteorological phenomena that affect the Caribbean islands. But some other phenomena, of smaller scale, such as intense rainfall events, swells, or air quality degradation, are of extreme importance for natural or health hazards. These examples show the need to use downscaling methods to exploit large scale meteorological or climatic information, and to obtain local and regional scenarios for the island areas. This is an important challenge, as sound scientific studies in these matters are eagerly expected. The aim of the research works exposed in the present dissertation is numerical simulation and analysis of the meso- and microscale mechanisms that induce diurnal and nocturnal local circulations in the Guadeloupe archipelago, using numerical meteorological models that are widely used in research and in operational forecasting.These works represent the first high-resolution (1 km to 111 m) numerical study of the lower atmosphere over the Guadeloupe archipelago. The Weather Research and Forecasting ARW 3.4 (WRF-ARW) model is used to simulate the troposphere from global scale to turbulence scale. Real cases of three typical weather types (80% of cases during a year) are examined during 48 hours : strong trade winds (STW), medium trade winds (MTW) and weak trade winds (WTW). These weather types are characterized by values of the local Froude number : 0.82 (STW), 0.41 (MTW) and 0.21 (WTW). Six domains have been selected for the dynamical downscaling : D01 (grid spacing of 27 km), D02 (grid spacing of 9 km), D03 (grid spacing of 3 km), D04 (grid spacing of 1 km), D05 (grid spacing of 333 m) and D06 (grid spacing of 111 m), including 70 vertical levels. The first four domains (D01 to D04) cover the Guadeloupe archipelago and are used in the meso-scale simulations with the planetary boundary layer scheme YSU (ensemble mean). Domain D05 (covering the Basse-Terre island and the middle of the archipelago) and domain D06 (covering the coastal and rural area of Le Petit Cul-de-Sac Marin and the urban area of Pointe-à-Pitre), are employed in the micro-scale simulation (LES) with the 3D TKE 1.5 order closure scheme. WRF has been 6 hourly reinitialized with the NCEP FNL global analyses (resolution of 1°). These simulations permitted to obtain 10-minutes meteorological variable fields with a very high resolution (111 m).Meso-scale and micro-scale model results have been evaluated with observational data from meteorological stations (field campaign Atmo-Mangrov, French Met Office).Once validated, the micro-scale model outputs have been used for the assimilation of the lagrangian particle dispersion model : FLEXPART. The coupling FLEXPART-WRF has been employed in domain D06, in order to analyze the dispersion of the nitrogen oxide plume emitted by the main power plant of the archipelago
Cissé, Soukèye. "Etude de la variabilité intra saisonnière des précipitations au Sahel : impacts sur la végétation (cas du Ferlo au Sénégal)". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066177/document.
Texto completo da fonteThe Sahel is characterized by a strong intra-seasonal variability of rainfall. This variability strongly affects ecosystems during the vegetation growth. The objective of this thesis is to characterize this variability at the local scale from the relationship between rainfall and vegetation dynamics, and to identify relevant indicators to better describe the variability in each season. This study is carried out in the Ferlo’s catchment, a basin located in northern Senegal. The first part is devoted to the characterization of the relationship between rainfall anomalies and growth of vegetation from remote sensing data TRMM3B42, RFE 2.0 SM-ECV (Soil Moisture) and MODIS LAI. Aiming that, the Ferlo basin is divided into 9 zones "homogeneous entity", in terms of vegetation cover class and soil type. For each one are analyzed the rain data from both databases, soil moisture and LAI over the period 2000-2010. In a second time, with a vegetation model adapted to the region forced by satellite rain fields, the LAI is simulated on several entities and is compared to the MODIS LAI, applying on the simulations the same methodologies as for observations. The results of this study show consistency between rainfall variations with both databases and soil moisture. The LAI variations are more strongly correlated with the soil moisture variations than with the rainfall. On the Ferlo, we observe that vegetation needs two weeks to respond to rainfall anomalies during the rainy season. At the season scale, the starting date of the rainy season does not affect the maximum LAI, unlike the duration and intensity of the dry spells. Entities located on sandy soil (ferruginous) have better sensitivity to rainfall fluctuations as those located on lithosoils. In addition, on entities located in the Southeast, the density of the shrub and tree vegetation induces a different phenological cycle than those of the herbaceous (lag of the maximum LAI). The model STEP, initialized with satellite rainfall data, reproduces after adjustment the vegetation growth stage in the entities where grassland dominates. The response of the simulated LAI to the rain anomalies is consistent with those observed, confirming the interpretation of observations. This study allowed to define the most relevant parameters that affect the dynamics of vegetation but also to highlight the capabilities of the model to describe the seasonal cycle of vegetation
Nicolle, Amandine. "Modélisation des marées et des surcotes dans les Pertuis Charentais". Phd thesis, Université de La Rochelle, 2006. http://tel.archives-ouvertes.fr/tel-00113552.
Texto completo da fonteBossavy, Arthur. "Caractérisation et prédiction probabiliste des variations brusques et importantes de la production éolienne". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00803234.
Texto completo da fonteVan, Rooij Mahaut. "Etude du rougissement hivernal du Douglas : entre températures douces & formation de glace". Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0154.
Texto completo da fonteThe Douglas fir is the first reforestation species in the Auvergne-Rhône-Alpes region and the second in France as a whole, and is of considerable economic importance in France, where 13 million trees are produced each year. Winter reddening affects young Douglas-fir (< 15 years old), affecting up to 80% of the plantation. A reddening tree has no silvicultural future and typically dies within a year after reddening. The objectives of my PhD thesis were to have a better understanding of winter reddening by identifying the climatic parameters that trigger reddening and, more importantly, the physiological mechanism(s) that cause needle reddening.A thorough literature review and bioclimatic analysis were undertaken to identify critical climatic factors. The literature synthesis identified certain climatic conditions characteristic of 'reddening' years, including anticyclonic periods after winter and/or alternating cold and warm periods. Both the literature synthesis and the bioclimatic analysis identified a combination of climatic variables: warm daily temperatures, high daily temperature amplitude, at least moderate wind speeds and relative humidity. However, the freeze-thaw cycles with cold night temperatures did not emerge from the climate analysis, although they are mentioned in the literature.In order to understand how Douglas fir reddens, we first identified gaps in our knowledge of winter reddening and proposed potential mechanisms, either single or interacting, that cause this physiological disorder: 1) winter drought leading to hydraulic failure, 2) photo-oxidative stress, and 3) premature deacclimation. Under controlled conditions, young Douglas fir trees were exposed to winter drought through a temperature differential between roots and canopy (TSOIL < 5°C; TMOY_AIR ~ 14°C). Some of these trees were exposed to light intensities that could induce photooxydative stress (> 1800 PPFD). Cold soil temperatures induced moderate water stress by limiting root water uptake, while warm air temperatures caused water loss at the needle level. However, Douglas fir was able to acclimate to this new environment and even resumed growth. Exposure to high light intensity did not cause irreversible damage to PSII or photooxydative stress. No reddening of the Douglas fir was observed, thus refuting hypothesis 2, but partially supporting hypothesis 1, as the canopy was not exposed to freezing stress. In the field, continuous measurements of young Douglas fir diameter variation were coupled with temperature/humidity measurements from four plots in the Massif Central from December 2020 to June 2023. Spring frosts in April 2021 on deacclimated Douglas fir did not result in needle reddening or cambial damages, thus failing to validate hypothesis 3. Nevertheless, comparison of a asymptomatic winter (2021) with a asymptomatic winter i.e. with winter reddening (2022) revealed significant hydraulic stress generated from the apex, associated with an anticyclone period in January 2022. Hydraulic failure could be exacerbated by daily transpiration, combined with freeze-thaw cycles that increase hydraulic stress, leading to canopy hydraulic failure that could explain needle desiccation and reddening. We therefore favour hypothesis 1, which should be tested under controlled conditions
Xiang, Yang. "Analyse dynamique en champ proche de la contribution des sources de composés organiques volatils, en région urbaine sous influence industrielle". Thesis, Littoral, 2011. http://www.theses.fr/2011DUNK0408.
Texto completo da fonteRecently, sources apportionment of Volatile Organic Compounds (VOC) has been the subject of a great numbers of studies, in order to determine their contributions to atmospheric pollution. However, the dynamical behavior of atmosphere, within its micro-meteorological scale, has never been taken into account in the sources-receptor approach, yet it is the main factor to interpret near-field physic-chemical measurements of air pollution, in an urban area under industrial influences. The complexity of such a study area results from not only the emission modes and the various industrial activities, but also the meteorological phenomenon in multi-scale, which influences the dispersion and transport in a small scale (tipically several kilometers). With measurements of 85 VOC (including 23 oxygenated VOC) during several months, we have developed an innovative methodology, associating the results of the PMF (Positive Matrix Factorization) modeling and the meteorological parameters, in order to identify the sources and to understand their dynamical behaviors. By introducing the vertical turbulence for the first time in this kind of analysis, the temperature and the solar radiation, as parameters of factor analyses, two behaviors have been distinguished, leading to identify the emissions near ground and in the upper part of surface layer. In this way, we have labeled the sources according to their nature as well as their emission mode, and we have highlighted the aged air mass containing secondary pollutants
Lemaire, Vincent. "Hiérarchisation des déterminants de la composition atmosphérique future en Europe". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX091/document.
Texto completo da fonteThe atmospheric composition is mainly driven by the emission of primary pollutants and precursors and meteorology. Because of its sensitivity to unfavorable weather patterns, air pollution is expected to be sensitive to climate change. That is why the aim of this work is to estimate the effect of climate change over air pollution in Europe at the end of the century. To achieve this we rely on modeling which allow to cover such timescales. To reduce uncertainties and quantify the effect of climate change on air quality, ensemble approaches should be applied. However, the computing cost of such methods is substantial. To overcome this issue we developed a statistical method which does not require forcing a chemistry and transport model with a large ensemble of climate projections. The results obtained with this statistical method are in good agreement with full chemistry-transport models when considering long time periods. But we point out the limits of the method when focusing on extreme pollution events. The statistical model can be used to assess the uncertainty of using a comprehensive ensemble of climate forcing in terms of air quality impacts. The statistical approach can also help identifying a subset of climate forcing that should be explored in priority to drive chemistry-transport models.Such a subset of climate models is however only available at a degraded vertical resolution on existing databases such as EuroCordex. To quantify the error induced when using a meteorological variables only saved for a few vertical levels, a sensitivity study focused on the impact of the vertical resolution of the meteorological data has been perfomed. We emphasized that a minimum of 10 vertical levels and some specific variables were required to study the impact of climate change on air quality to keep the error lower than the climate change signal.Finally, we use the statistical method to compare the climate change effect and the future emissions reduction impact estimated also with a surrogate model. We exhibit that the magnitude of climate benefit for PM2.5 will be comparable to the emissions reductions of the dominant sector in each country studied. These emissions decreases will therefore be reinforced the climate change. On the opposite, for SOMO35, the climate penalty will jeopardize the emission reductions between 2010 and 2050. We also evaluate that climate change will become more important than the expected reduction emissions signal
Alomari, Asaad. "Evaluation des risques d’altération d’origine thermo-hydro-mécanique des pierres du patrimoine bâti". Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2012/document.
Texto completo da fonteThis study deals with the ageing of limestone structures as a result of the interaction with their environment. It is based on the characterization of both the material and the local climatic conditions. The objective of this thesis is to study the role of climatic conditions in the degradation of stone by quantitative estimation of the weight of the different physical weathering processes: freezing-thawing, condensation and restrained hygro-thermal dilations. Two major historic sites were selected: the Château of Chambord in France and the site of Al-Nimrud City in Iraq, an ancient Assyrian capital, built in 1280 BCE. The French materials studied are tuffeau and Richemont stone, extensively used as a substitute for tuffeau restoration during part of the 20th century. The Iraqi materials studied are samples cored in situ in original weathered stones, original healthy stones, and the stone that could be used as a substitute for restoration. The approach chosen for damage risk assessment starts by the realization of a multiphysics and multiscale experimental characterization campaign of the limestone used at Chambord, added to the collection of meteorological data at Chambord thanks to a weather station supplemented by situ stone measurements. The damage risk assessment is obtained by the combined use of climate data and material characterization, through the calculation of the impact of thedifferent physical weathering processes, which required some methodological developments. The proposed damage risk assessment methodology is then applied to Al-Nimrud site. Finally, a preliminary digital health record of the most prominent monument of Al-Nimrud - the Al-Ziggurat - is carried out to diagnose its durability
Roupsard, Olivier. "Ecophysiologie et diversité génétique de Faidherbia albida (Del. ) A. Chev. (syn. Acacia albida Del. ), un arbre à usages multiples d'Afrique semi-aride : fonctionnement hydrique et efficience d'utilisation de l'eau d'arbres adultes en parc agroforestier et de juvéniles en conditions semi-contrôlées". Phd thesis, Nancy 1, 1997. http://www.theses.fr/1997NAN10279.
Texto completo da fonte