Dissertations / Theses on the topic 'Observations au sol (météorologie)'
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Abeed, Rimal. "IASI ammonia observations to study land-use change, soil-atmosphere exchange and the effect of meteorology." Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS274.
Ammonia (NH3) is the most abundant usable form of nitrogen in the environment, and one of the main gases emitted from agriculture. NH3 contributes largely to the loss in biodiversity, fine particulate matter (PM2.5) pollution episodes, and acidification of the water and soil bodies. Previous studies have shown that emissions of ammonia from agricultural intensification are constantly increasing, compared to pre-industrial times. Climate warming is expecting to enhance ammonia emissions, especially under the stress of increasing population, and food demand. In my thesis I study the temporal and spatial evolution of ammonia in agricultural regions around the globe as measured by IASI (Infrared Atmospheric Sounding Interferometer). The IASI series of instruments were launched aboard the Metop satellites in 2007, 2013 and 2018 on MetopA, B and C respectively. I first study the effect of meteorological fluctuations on atmospheric IASI-NH3 concentrations from agricultural practices. I then focus on the soil – atmosphere exchange by deriving NH3 soil emission factor, with an emphasis on agricultural soils in Europe, and during the growing season. To perform my studies, I use a variety of datasets: meteorological data from the EUropean Organisation for the Exploitation of METeorological SATellites (ECMWF) reanalysis (ERA5), land cover type and burned area from the moderate resolution imaging spectroradiometer (MODIS), and model simulation data from the chemical transport model GEOS-Chem. Finally, I study the effect of land-use/cover change on atmospheric ammonia, coupled with the effect of meteorology in regions of conflict. For this, I look at the Syrian civil war, and I link the political course of events with the fluctuations in atmospheric ammonia in key regions in Syria
El, Kattar Marie-Thérèse. "Caractérisation instrumentale et capacité de mesure des GES du prototype instrumental CHRIS." Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR011.
To quantify the influence of human activities on the evolution of atmospheric composition, accurate and continuous measurements are essential. Ground-based high-spectral-resolution infrared measurements are an efficient way to obtain accurate tropospheric abundances of different gaseous species, in particular greenhouse gases (GHGs) such as CO2 and CH4. Many ground-based spectrometers are used in the NDACC and TCCON networks to validate the Level 2 satellite data, but their large dimensions and heavy mass make them inadequate for field campaigns. To overcome this drawback, the use of portable spectrometers was recently investigated. In this context, the work of this thesis consisted in characterizing the instrumental prototype CHRIS (Compact High-Spectral-Resolution Infrared Spectrometer). This instrument has unique characteristics such as its high spectral resolution (0.135 cm-1 non-apodized) and its wide spectral range (680 to 5200 cm-1). Its main objective is the characterization of gases and aerosols in the thermal and shortwave infrared regions. Therefore, it requires high radiometric precision and accuracy, which are obtained by performing spectral and radiometric calibrations as well as the characterization of its instrumental line shape. Furthermore, CHRIS’s capabilities to retrieve vertical CO2 and CH4 profiles are presented through a complete information content analysis, a channel selection and an error budget estimation in the attempt to join ongoing campaigns such as MAGIC (Monitoring of Atmospheric composition and Greenhouse gases through multi-Instruments Campaigns) to monitor GHGs and validate the actual and future space missions such as IASI-NG and Microcarb
Legorgeu, Carole. "Amélioration des estimations quantitatives des précipitations à hautes résolutions : comparaison de deux techniques combinant les observations et application à la vérification spatiale des modèles météorologiques." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00872131.
Bourgeois, Elsa. "Les nuages de mi-niveau en Afrique de l'Ouest : observation, caractérisation, modélisation." Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19450/7/BOURGEOIS_Elsa.pdf.
Etienne, Christian. "Réalisation et évaluation d'un sodar monostatique : étude des signatures sodars en fonction de paramètres météorologiques." Orléans, 1986. http://www.theses.fr/1986ORLE0404.
Chen, Hong-Bin. "Simulation d'observations satellitaires passives en micro-onde : influence de la nébulosité et des précipitations sur les températures de brillance : inversion de paramètres nuageux à partir des mesures du sondeur micro-onde Météosat." Lille 1, 1991. http://www.theses.fr/1991LIL10029.
Chapon, Benoît. "Etude des pluies intenses dans la région Cévennes-Vivarais à l'aide du radar météorologique : régionalisation des traitements radar et analyse granulométrique des pluies au sol." Université Joseph Fourier (Grenoble), 2006. http://www.theses.fr/2006GRE10236.
We have studied in the present thesis the development of an automated rainfall typing procedure into convective and stratiform regions based on the use of 3D weather radar data. First, we have shown the strong influence of the radar sampling properties for two algorithms already proposed in the literature by Steiner et al. (1995) and Sanchez-Diezma et al. (2000) for the detection of convective and stratiform precipitation, respectively. This problem was partially overcome by a decision tree and a coupling of the rain typing and the vertical profile of reflectivity (VPR) identification. The final algorithm is shown to significantly improve the raintyping at long ranges (e. G. , greater than 60 km). On the other hand, we have conducted an experiment in Alès during the autumn 2004 to document the Cévennes drop size distributions (DSD) at ground level by using an optical disdrometer. We have first implemented various methods to establish the reflectivity - rain rate relationship (Z-R relationship). Their respective merits were assessed through a self-consistency procedure based on DSD data alone. Then we have studied the seasonal, inter-storm and inner-storm variability of the Z-R relationship and shown the major influence of the inner-storm variability. Finally, we have performed a preliminary study of the link between the 3D radar data and the ground-based DSD data through a comparison of DSD-based and radar-based rain typing
Brenot, Hugues. "Potentiel de la mesure GPS sol pour l'étude des pluies intenses méditerranéennes." Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00012085.
Auray, Christophe. "La météorologie : savoir et pratiques populaires en Bretagne au moment de la naissance d'une science." Nantes, 2008. http://www.theses.fr/2008NANT3028.
Rojas, Muñoz Oscar Javier. "Le rôle des nuages et des processus de surface sur la variabilité de la température à l'échelle locale : analyse d'observations multi-variables." Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASJ016.
Large-scale dynamics dominate the surface temperature variations and atmospheric conditions in Western Europe to the first order. However, this large-scale air mass circulation alone does not explain all the temperature and precipitation variability. At the second order, this variability depends on small-scale processes via the atmospheric boundary layer and the surface energy balance (SEB), which itself depends largely on radiation and thus on cloud properties.The objective of this thesis is to better understand local processes and their influence on local climate variability, with a particular focus on the role of clouds.To do so, the first objective is to quantify the specific local contribution of the main SEB terms acting on short-term (i.e. hourly) temperature variations in Ile de France, and to determine their importance and the conditions under which one or the other of these terms will be preponderant. The four terms acting on the temperature variations are radiation (which can be separated into clear sky and cloud contribution), heat exchange with the atmosphere, heat exchange with the ground, and temperature advection. We develop the OTEM model that allows us to estimate these terms almost exclusively from observations, using the SIRTA-ReOBS dataset. We show that the sum of these four terms gives a good estimate of the hourly temperature variations. The weight of each term of the SEB on the hourly temperature variations is analyzed using the random forest method, whose main advantage is its ability to handle thousands of input variables and identify the most significant ones. This analysis showed that regardless of the season, clouds are the main modulator of the sun's effect on hourly temperature variations during the day, and they completely dominate during the night.The second objective is to study the specific role of clouds in temperature variations. For this purpose, other observations including lidar profiles have been used, exclusively under cloudy conditions. Several cases were created from the radiative effect of clouds during the day and night to (i) better understand how they affect the state of the atmosphere and thus other variables at the surface, and (ii) characterize the type of predominant clouds according to their radiative effect.Finally, we investigate the spatio-temporal variability of the previously obtained results: (1) spatial variability by applying the same method to the Meteopole site in Toulouse to understand how local specific conditions affect each of the terms involved in the surface temperature variations; (2) variability as a function of large-scale air circulation conditions by separating our results as a function of North Atlantic weather patterns
Quesada, Benjamin. "Extrêmes de températures en Europe : caractéristiques, retroactions, sol atmosphère et prévisibilité." Versailles-St Quentin en Yvelines, 2014. http://www.theses.fr/2014VERS0002.
Extreme temperature events largely impact socio-economic and environmental systems. Combining statistical analyses and modelling experiments in Europe, I show that in winter, global climate models simulate cold waves and associated climate variables. However, they overestimate their number by about 40%. A correct representation of snow cover and of the snow/atmosphere feedback reduces this bias in the models. In summer, they also simulate heat waves but tend to underestimate some linked physical mechanisms. Soil-moisture/atmosphere feedback explains the asymmetric predictability of heat waves: while high spring precipitation in Southern Europe contribute to their inhibition, in case of deficit, heat waves can develop or no. As soils become drier, this seasonal predictability is likely to be reduced in the future
Affre, Christine. "Méthodologie de la mesure (aéroportée et au sol) des flux turbulents. Application à l'ozone aux échelles locale et régionale." Toulouse 3, 1997. http://www.theses.fr/1997TOU30112.
Tabary, Pierre. "Observations radar de systèmes précipitants orographiques pendant l'expérience MAP." Toulouse 3, 2002. http://www.theses.fr/2002TOU30031.
Artru, Juliette. "Observations au sol ou par satellite et modélisation des signaux ionosphériques post-sismiques." Paris, Institut de physique du globe, 2001. http://www.theses.fr/2001GLOB0006.
Seoane, Corral Lucía. "Interprétation géophysique du mouvement du pôle : apport des observations de géodésie spatiale, de météorologie, d'océanographie et d'hydrologie." Observatoire de Paris (1667-....), 2010. https://theses.hal.science/tel-01958536.
The polar motion excitation is mainly due to the mass transport of the atmosphere and the oceans. So far, the observed motion is not fully explained from seasonal to diurnal scales. Our effort has focused on the Chandler wobble as well as fluctuations with period smaller than 50 days and diurnal variations, which remain still partially unexplained. We show that the atmospheric and oceanic mass redistributions are the principal causes of the Chandler wobble irregularities and the rapid polar motion of periods between 3 and 50 days. However, major differences persist at diurnal scales. Moreover, the redistributions of the continental water are important but, modelling those processes is imprecise due to the complexity and lack of observations of terrestrial hydrology. Current models must be then validated and compared to the observed polar motion. We show that the hydrological models, coupled with oceanic and atmospheric effects, improve the seasonal and long term mass balance. Thanks to space mission Gravity Discovery and Climate Experiment (GRACE), the total mass redistribution on the Earth can be determined with a different approach. Four analysis centers provide temporal variations of spherical harmonics C20, C21 and S21 of the gravity field that are proportional to the length of day and polar motion excitations caused by surface mass changes. We have analized the latest updates of these series. Despite a significant level of noise, their hydrological residual matches reasonably well the observed polar motion
Jankowiak, Isabelle. "Surveillance des aérosols désertiques à partir de l'imagerie METEOSAT et estimation de leur impact radiatif." Lille 1, 1992. http://www.theses.fr/1992LIL10029.
Yu, Jingmei. "Représentation de l'effet des vents anabatiques sur le déclenchement de la convection profonde dans un modèle de climat." Paris 6, 2010. http://www.theses.fr/2010PA066254.
Guedj, Stéphanie. "Assimilation des observations satellitaires au-dessus des surfaces continentales." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/2285/.
In numerical weather prediction models, satellite observations are essential to perform optimal atmospheric analyses. Despite the performance and maturity of current assimilation systems, for different reasons these observations remain highly underutilized over land surfaces. This study aims to improve the description of the surface (temperature and emissivity) to better assimilate remote sensing observations in models. Initially, the validity of surface approximations used to calculate the microwave emissivity over snow surface was evaluated (over the Antarctica region). The impact of several surface approximations for microwave emissivity computation was studied and it was found that the quality of brightness temperature simulations was improved using relevant approximations. Thereafter, the objective was to extend the assimilation of infrared surface-sensitive observations over land which were until now rejected by the assimilation system. Recent researches to assimilate microwave observations over land have shown that this objective can be reached with an adequatly described surface. A large part of my PhD was devoted to the evaluate the potential to retrieve land surface emissivity and land surface temperature from data provided by the SEVIRI radiometer (Spinning Enhanced Visible and Infrared Imager) onboard METEO-SAT SECOND GENERATION. The strong sensitivity to clouds and the large bias found in the land surface temperature computed by the ALADIN meso-scale model encouraged me to use infrared emissivity climatology from the Land-SAF (EUMETSAT Land Surface Analysis - Satellite Application Facilities) rather than direct retrieval from SEVIRI observations. I have shown that, with these climatologies, the land surface temperature could be retrieved at channel IR10. 8 with the same quality as the one from the Land-SAF. The use of this temperature as boundary conditions of the radiative transfer model improve the brightness temperature simulations at SEVIRI channels. For the first time, assimilation experiments were conduced within the two limited area models to assess the impact of the assimilation of surface-sensitive infrared observations over the analysis and forecast skills. The predominant impact was observed on the analysis of the moisture with a tendency to dry out the atmosphere in summer and increase moisture in winter. The change in moisture was successfully evaluated near the surface, using independent GPS data. The impact on forecasts, in particular the cumulative precipitation forecasts, was considered to be positive mainly over southern Europe
Cerisier, Alexis. "Variations climatiques et infarctus du sujet jeune : à propos de 46 observations." Saint-Etienne, 1992. http://www.theses.fr/1992STET6420.
Kebe, Cheikh Mouhamed Fadel. "Relation entre les intégrales spatio-temporelles de la couverture nuageuse et la pluie au sol aux latitudes tropicales : implications pour la mesure des précipitations depuis l'espace." Toulouse 3, 2005. http://www.theses.fr/2005TOU30266.
Ayoub, Nadia. "Variabilite du niveau de la mer et de la circulation en mediterranee a partir de donnees altimetriques et de champs de vent : comparaison avec des simulations numeriques." Toulouse 3, 1997. http://www.theses.fr/1997TOU30254.
Spiga, Aymeric. "Dynamique méso-échelle de l'atmosphère martienne : développement d'un modèle météorologique et analyse des observations OMEGA / Mars Express." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00347021.
Kolassa, Jana. "Soil moisture retrieval from multi-instrument satellite observations." Paris 6, 2013. http://www.theses.fr/2013PA066392.
In this thesis, a neural network based retrieval algorithm has been developed to compute surface soil moisture from a combination of microwave, infrared and visible satellite obser- vations. A global estimate of monthly mean soil moisture values has been computed for the period 1993-2000 and is provided on an equal-area grid with an equatorial resolution of 0. 25◦. This soil moisture estimate has been evaluated against modelled, remotely sensed and in situ observations and was found to perform well on different spatial and temporal scales. An information content showed that each of the various satellite observations con- tributes information about a different soil moisture variation, with the active microwave data being more sensitive to the temporal evolution and the thermal infrared data better capturing the spatial patterns. Furthermore, a synergy analysis revealed that the combina- tion of all observations permits a reduction of the retrieval uncertainty by more than 18% and that the neural network methodology optimally exploits the synergy of observations compared to other approaches. A joint analysis of various remotely sensed datasets of ter- restrial water cycle components demonstrated the coherence of the retrieved soil moisture with other retrieval products and with global hydrological processes. This underlined its potential to be used for observation-based studies of the terrestrial water cycle. Finally, it has been shown that the proposed neural network methodology also provides an effective tool to evaluate Earth System Models on both a variable and a process basis
Jaffrain, Jérôme. "Effet des essences forestières sur le fonctionnement organo-minéral d'un sol acide: observations et modélisations." Phd thesis, Université Henri Poincaré - Nancy I, 2006. http://tel.archives-ouvertes.fr/tel-00171476.
Malakooti, Hossein. "Météorologie et qualité de l'air dans une grande ville : application sur Téhéran, Iran." Phd thesis, Ecole des Ponts ParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00555962.
Joulin, Pierre-Antoine. "Modélisation à fine échelle des interactions entre parcs éoliens et météorologie locale." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0135.
The development of wind energy, encouraged by the french Multiannual Energy Program, raisesnew questions. Some parks will be located on mountainous and offshore terrains. To forecast the energy production and try to optimize it, a better understanding of the flow within wind farm on thattype of terrain is needed. In addition, modern offshore wind turbines are getting larger and willinteract more strongly with local weather. It seems important to characterize these interactions. To respond to this industrial and environmental challenge, a new digital toolwas created during this thesis work. The first part of this manuscript focuses on the concepts andtheoretical models of the Atmospheric Boundary Layer (ABL) and wind turbines. In particular, theMeso-NH meteoro- logical model, used in the Large-Eddy Simulation (LES) framework, andsimplified models of wind turbines have been investigated : Actuator Disk (AD) with and without rotation and the Actuator Line (AL). The second part is devoted to the development and validation of the coupled tool. By implementing the AD and AL methods within Meso-NH, it becomes possible to simulate the presence of wind turbines in a realistic atmospheric boundary layer. A firstvalidation step is based on a wind tunnel experiment, involving five wind turbines on a hill, toanalyze the coupling with the non-rotating Actuator Disk. A second focuses on the MextNext experiment of a small wind turbine, to study the coupling with the Actuator Line. All the resultsobtained are very satisfactory. The third part focuses on the potential impact of wind farms on localweather. The ability of the tool to reproduce complex meteorological interactions has been demonstrated by simulating the case of the Horns Rev 1 photos. The cloud development obtainedby the coupled system demonstrates the potential of the developed tool. In order to characterizethe impact of future offshore parks on the local meteorology, large wind turbines immersed in a thin atmospheric boundary layer were simulated. A clear weather case and a cloudy one wereexamined. Additional studies will be needed to complement these preliminary results. Thus, newMeso-NH parameterizations make now possible to represent wind turbines in a realistic atmosphere, widening the scope of possible CFD simulations for wind farms
Samouëlian, Anatja. "Analyse tridimensionnelle non destructive de la fissuration d'un sol cultivé à partir de mesures de résistivité électrique." Orléans, 2004. http://www.theses.fr/2004ORLE2008.
Kohn, Jacqueline. "Inversion des observations spatiales micro-ondes pour la détermination de la température du sol en présence de neige." Thèse, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/2812.
Mestre, Olivier. "Méthodes statistiques pour l'homogénéisation de longues séries climatiques." Toulouse 3, 2000. http://www.theses.fr/2000TOU30165.
Kocha, Cécile. "Interactions entre poussières désertiques et convection profonde en Afrique de l'Ouest : observation et modélisation à échelle convective." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1547/.
West Africa shows the greatest uncertainties about the evolution of precipitations. Moreover, in a warming climate, this region is very suceptible to droughts which can be devastating for the local populations. This region is also the main source of desert dust in the world where production is increasing due to over-exploitation of soils. Besides the fact that dust is associated with outbreaks of meningitis, it also has a direct impact on the atmosphere since it absorbs and scatters solar radiation causing a change in atmospheric heating. By altering the atmospheric radiation budget, the dust can influence the fine-scale turbulence up to large-scale atmospheric circulations. Also, the processes involved in the interactions between desert dust and atmosphere are very diverse, complex, and constitute a major source of uncertainty in numerical prediction. In order to understand these processes, a modeling framework was developed which englobes fine to regional scales. It explicitly resolves the deep convection, the dust life cycle and its radiative impacts, but also considers their interactions over all of West Africa at a monthly scale. Under dust storm conditions during the dry season, the high amount of dust raised by the fronts, leads to a near doubling of the storm intensity. By this positive feedback, explicit modeling of dust improves the predictability of the storm. During the establishment of the monsoon in June, the frequent occurrence of dust is actively involved in the initiation of the monsoon onset: On the one hand, by weakening the Saharan heat low, and on the other hand, by strengthening the northward movement of the heart of the inter-tropical convergence and jets. At finer scales, the presence of dust also impacts the location and the diurnal cycle of convective systems. Also, dust can change the cloud cover which leads to stronger radiative impacts than the direct effect of dust. This thesis suggests that accounting for the coupling between the dust and the atmosphere may improve the forecast skill in West Africa
Kerr, Yann H. B. "Echanges énergétiques à l'interface sol-atmosphère par télédétection : complémentarités des différents domaines de longueurs d'ondes." Toulouse 3, 1992. http://www.theses.fr/1992TOU30109.
Pellenq, Jennifer. "Couplage de la modélisation hydrologique avec la modélisation des transferts sol-végétation-atmosphère : application à la spatialisation et à l'assimilation des données du satellite SMOS." Toulouse 3, 2002. http://www.theses.fr/2002TOU30137.
Bouillon, Marie. "Températures atmosphériques homogènes dérivées des observations satellitaires IASI : restitution, variations spatio-temporelles et événements extrêmes." Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS317.pdf.
The IASI instruments, launched in 2006, 2012 and 2018, observe radiance spectra from the Earth-atmosphere system, allowing us to retrieve atmospheric temperatures. The EUropean organisation for the exploitation of METeorological SATellites (EUMETSAT) computes surface and atmospheric temperatures from IASI observations since 2007. To improve the quality of the retrieved temperatures, EUMETSAT has performed several updates on the temperature processing algorithm. In this work, we show how the EUMETSAT temperature record is inhomogeneous and therefore not adapted to the study of temperatures on the long term. Therefore, a new atmospheric temperature product was computed from IASI spectra with an artificial neural network, using IASI radiances as input and ERA5 reanalysis temperatures as output. The temperatures retrieved with the neural network were validated against ERA5 temperatures and radiosounding temperatures. The validation showed good agreement between the three datasets from 750 to 7 hPa. At 2 hPa, the quality of the temperature products decreases because of the low amount of information on temperature within the IASI spectra at this altitude. This new homogeneous temperature record was then used to study extreme events, in particular Sudden Stratospheric Warmings (SSW). This work studies several SSWs that have happened since 2007, and shows that IASI is perfectly suited to study both temperature and ozone changes during these events. The temperatures were also used to observe the cold and heat waves that happened in the past few years. Finally, the temperatures were used to compute trends over the 2008-2020 period. The troposphere is warming, especially in the upper equatorial troposphere and in the Arctic. The stratosphere north of 50°S is also warming due to the slow ozone hole recovery. In the rest of the stratosphere, the temperatures are decreasing. This thesis presents an homogenous and independent temperature data record from IASI. The methods developed can and will be applied to the rest of the IASI mission and to its successor, the IASI-New Generation mission, which will launch in 2024
Taillardat, Maxime. "Méthodes Non-Paramétriques de Post-Traitement des Prévisions d'Ensemble." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV072.
In numerical weather prediction, ensemble forecasts systems have become an essential tool to quantifyforecast uncertainty and to provide probabilistic forecasts. Unfortunately, these models are not perfect and a simultaneouscorrection of their bias and their dispersion is needed.This thesis presents new statistical post-processing methods for ensemble forecasting. These are based onrandom forests algorithms, which are non-parametric.Contrary to state of the art procedures, random forests can take into account non-linear features of atmospheric states. They easily allowthe addition of covariables (such as other weather variables, seasonal or geographic predictors) by a self-selection of the mostuseful predictors for the regression. Moreover, we do not make assumptions on the distribution of the variable of interest. This new approachoutperforms the existing methods for variables such as surface temperature and wind speed.For variables well-known to be tricky to calibrate, such as six-hours accumulated rainfall, hybrid versions of our techniqueshave been created. We show that these versions (and our original methods) are better than existing ones. Especially, they provideadded value for extreme precipitations.The last part of this thesis deals with the verification of ensemble forecasts for extreme events. We have shown several properties ofthe Continuous Ranked Probability Score (CRPS) for extreme values. We have also defined a new index combining the CRPS and the extremevalue theory, whose consistency is investigated on both simulations and real cases.The contributions of this work are intended to be inserted into the forecasting and verification chain at Météo-France
Lesueur, Chloé. "Relations entre les mesures de mouvements du sol et les observations macrosismiques en France : Etude basée sur les données accélérométriques du RAP et les données macrosismiques du BCSF." Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/LESUEUR_Chloe_2011.pdf.
Comparison between accelerometric and macroseismic observations is made for three Mw~4. 5 earthquakes of eastern France between 2003 and 2005. Scalar and spectral instrumental parameters are processed from the accelerometric data recorded by nine accelerometric stations located between 29km and 180km from the epicentres. Macroseismic data are based on the French Internet reports. In addition to the individual macroseismic intensity, analysis of the internal correlation between the encoded answers highlights four predominant fields of questions, bearing different physical meanings: 1) “Vibratory Motions of small objects”, 2) “Displacement and Fall of Objects”, 3) “Acoustic Noise”, and 4) “Personal Feelings”. Best correlations between macroseismic and instrumental observations are obtained when the macroseismic parameters are averaged over 10km radius circles around each station. Macroseismic intensities predicted by published PGV-intensity relationships quite agree with the observed intensities, contrary to those based on PGA. The correlations between the macroseismic and instrumental data, for intensities between II and V (EMS-98), show that PGV is the instrumental parameter presenting the best correlation with all macroseismic parameters. The correlation with response spectra, exhibits clear frequency dependence over a limited frequency range [0. 5-33Hz]. Horizontal and vertical components are significantly correlated with macroseismic parameters between 1 and 10Hz, a range corresponding to both natural frequencies of most buildings and high energy content in the seismic ground motion. Between 10 and 25Hz, a clear lack of correlation between macroseismic and instrumental data is observed, while beyond 25Hz the correlation coefficient increases, approaching that of the PGA correlation level
Vionnet, Vincent. "Études du transport de la neige par le vent en conditions alpines : observations et simulations à l'aide d'un modèle couplé atmosphère/manteau neigeux." Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00781279.
Zitouna-Chebbi, Rim. "Observations et caractérisation des échanges d'eau et d'énergie dans le continuum sol-plante-atmosphère en condition de relief collinaire : cas du bassin versant Kamech, Cap Bon, Tunisie." Montpellier SupAgro, 2009. http://www.theses.fr/2009NSAM0027.
Drigeard, Elise. "Microphysique glacée des systèmes convectifs observés dans le cadre de Megha-Tropiques en Afrique de l'Ouest : comparaison des mesures aéroportées avec des radars sol et un modèle numérique." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22531/document.
Tropical meteorology is a major issue for atmospheric physics and earth’s climate. The Megha-Tropiques satellite combines several teledetection instruments which need complex restitution algorithms. This work contributes to the development of validation’s strategies for these algorithms. This requires a better knowledge of the tropical mesoscale convective systems’ (MCS) ice phase. In this thesis, we use data from the Niamey’s (Niger) campaign, which took place during summer 2010. Numerous MCS with high Ice Water Content (IWC) were analyzed with an airborne instrumentation and ground radars. Reflectivity Zin-situ is calculated using airborne microphysic probes’ information and a mass-diameter relationship. A spatial and temporal interpolation technique is developed to colocalize the aircraft position with ground radar measurements. This method leads to the validation of Zin-situ calculation. The relationship between reflectivity and IWC is not satisfactory for the MIT precipitation radar. Moreover, the cloud radar gives better informations about the IWC than the precipitation radar. Indeed, precipitation radars are too sensitive to large ice crystals. Therefore, in-situ measurements are essential to get microphysic information in order to validate restitution algorithms used by satellites. They can’t be replaced by ground based reflectivity measurements. The WRF (Weather Research and Forecasting) model was used in order to get a better knowledge of MCS. In this work, we analyzed one case study. For this case, WRF generates a typical squall line but it doesn’t correctly reproduce every observed characteristics. Several dynamical and microphysical differences appear between simulation and observations. The simulated reflectivity field is analyzed by CFAD (Contoured Frequency by Altitude Diagrams) and it shows a general underestimated reflectivity compared to the observations. The Thompson microphysic scheme is replaced by the more complex Morrison scheme, but this modification doesn’t improve the results of the simulation. Consequently, the WRF model isn’t yet efficient enough to help with the restitution algorithms’ validation
Erdmann, Félix. "Préparation à l'utilisation des observations de l'imageur d'éclairs de Météosat troisième génération pour la prévision numérique à courte échéance." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30273.
As an initial analysis, an intercomparison of lightning observations over Corsica from the Lightning Imaging Sensor on the International Space Station (ISS-LIS), the Low Frequency (LF) Meteorage network, and the SAETTA Lightning Mapping Array (LMA) reveals that coincident flashes of all three lightning locating systems can be identified. Large and long-duration flashes are more likely detected by both ISS-LIS and Meteorage than small and short-duration flashes. Using the information provided by SAETTA, it is found that the flash detection efficiency of ISS-LIS degrades for flashes detected by Meteorage that do not extend over 7 km of altitude. This intercomparison methodology is further applied to analyze records of ISS-LIS relative to National Lightning Detection Network (NLDN) observations over the southeastern USA. Overall, the flash characteristics analyzed in both French and US regions are not only similar from ISS-LIS records, but also when comparing their statistics as depicted by Meteorage and NLDN. It is concluded that Meteorage and NLDN detect and locate lightning similarly. With the advent of the Geostationary Lightning Mapper (GLM) concurrent geostationary (GEO) GLM and ground-based NLDN lightning observations are analyzed in detail to develop a complex algorithm to generate GEO lightning pseudo-observations from NLDN records. The so-called GEO lightning pseudo-observation generator first relates NLDN and GLM flash characteristics to train machine learning models, and secondly creates pseudo-GEO events from the simulated GEO flash characteristics. Finally, this generator is applied to simulate synthetic Meteosat Third Generation (MTG) Lightning Imager (LI) observations over France using Meteorage records as input. Eventually, Flash Extent Density (FED) is inferred from that pseudo MTG-LI data. Pseudo MTG-LI FED serves as data source for a new lightning data assimilation (LDA) scheme in the French operational model AROME-France. Here, a 1-dimensional Bayesian (1DBay) retrieval inverts the FED observations and provides relative humidity (RH) profiles. The 1DBay proves to suppress spurious convection and promote convection in regions with positive FED. As a last step, retrieved RH profiles are assimilated using the 3D variational (3DVar) system of AROME-France. Despite promising results of the 1DBay, the AROME-France analysis contradicts the retrieved RH profiles in that humidity is increased in some regions where the retrieved RH profiles suggest a reduction of the background humidity
Rossel, Frédéric. "Influence du Niño sur les régines pluviométriques de l'Equateur." Montpellier 2, 1997. http://www.theses.fr/1997MON20122.
Remy, Sophie. "Etude et utilisation d'une camera infrarouge optimisee pour les observations a partir du sol dans la gamme de longueur d'onde 10 microns." Paris 7, 1991. http://www.theses.fr/1991PA077198.
Söhne, Nathalie. "Validation des prévisions de nuages et de précipitations à mésoéchelle par l'observation satellite." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/102/.
An original methodology combining the model-to-satellite approach and skill score calculation has been developped in order to objectively evaluate mesoscale models. This method has been applied on three study cases using the Meso-NH model. The first case is about the validation of an ensemble of contrasted precipitating situations, at mid-latitude, used for a data base. It also shows the link between the forecast quality and the meteorological nature of the situation. The second, is an ensemble of forecasts done to quantify the influence on the predictibility of an extreme event when modifications were done on initial conditions and model configurations. The last case allowes to quantify the reliability of a series of AMMA previsions and its variability with synoptic factors
Escadafal, Richard. "Caracterisation de la surface des sols arides par observations de terrain et par teledetection." Paris 6, 1989. http://www.theses.fr/1989PA066175.
de, Montera Louis. "Etude de la variabilité micro-échelle des précipitations : application à la propagation des ondes millimétriques en SATCOM." Versailles-St Quentin en Yvelines, 2008. http://www.theses.fr/2008VERS0021.
Attenuation time series at EHF band exhibit characteristics similar to some stock exchange rates, which suggests that prediction models originally developed in the finance field might be appropriate. The analysis leads to a non linear ARIMA/GARCH model. In order to predict the uplink attenuation from the downlink attenuation that operates at a different frequency, a frequency scaling model has been added to the prediction model. In order to better understand the link between attenuation and its physical causes, an approach based on rain fractal properties is then presented. An assessment of the effect of rain-no rain intermittency on the multifractal analysis shows that it provokes a break in the scaling and may lead to biased parameters. The multifractal analysis is then performed event by event, i. E. With uninterrupted rain periods. The results show that rain can be modeled by a FIF (Fractionally Integrated Flux) which is threholded in order to simulate rain-no rain intermittency
Poulin, Leboeuf Laurence. "Analyse statistique des facteurs climatiques et géomorphologiques associés aux mouvements de terrain dans les argiles des mers post-glaciaires au Québec méridional." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66412.
Cotton, Julien. "Analyse et traitement de données sismiques 4D en continu et en temps réel pour la surveillance du sous-sol." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM023.
3D seismic reflection is widely used in the oil industry. This standard subsoil auscultation method provides information on geological structures and can be used to build reservoir models. However, the properties derived from3D (and 2D) seismic data are only static: 3D does not allow to evaluate the changes with calendar time. The addition of a temporal dimension to 3D data is obtained by repeating the measurements at several dates separated by several months or even several years. Thus, 4D seismic (time-lapse) makes it possible to measure and to analyze the changes of the subsoil in the long term. Since the 90s, this method is used worldwide at sea and on land. To carry out a much more frequent monitoring (daily), even continuous (a few hours) of the subsoil, CGG developed, in collaboration with Gazde France (now ENGIE) and Institut Français du Pétrole (now IFPEN), a solution based on buried sources and receptors: SeisMovie. SeisMovie was originally designed to monitor and map the gas front in real time during geological disposal operations. It is also used to observe the steam injection required for heavy oil production. In this thesis, we bring contributions to three challenges arising in the processing of seismic data from this system. The first one concerns the attenuation of near-surface variations caused by "ghost" waves that interfere with primary waves. The second one concerns the quantification of subsurface changes in terms of propagation velocity variation and acoustic impedance.The third one concerns real-time: the data processing must be at least as fast as the acquisition cycle (a few hours). Infact, the analysis of the data must enable the reservoir engineers to make quick decisions (stop of the injection, decreaseof the production). In a more general context, there are conceptual similarities between 3D and 4D. In 4D, the repeated acquisitions are compared with each other (or with a reference). In 3D, during acquisition, field geophysicists compare unitary shot points with each other to assess the quality of the data for decision-making (reshooting, skipping orcontinuing). Therefore, some 4D real-time tools developed during this thesis can be applied. A new approach called TeraMig for automated quality control in the field will also be presented
Taillardat, Maxime. "Méthodes Non-Paramétriques de Post-Traitement des Prévisions d'Ensemble." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV072/document.
In numerical weather prediction, ensemble forecasts systems have become an essential tool to quantifyforecast uncertainty and to provide probabilistic forecasts. Unfortunately, these models are not perfect and a simultaneouscorrection of their bias and their dispersion is needed.This thesis presents new statistical post-processing methods for ensemble forecasting. These are based onrandom forests algorithms, which are non-parametric.Contrary to state of the art procedures, random forests can take into account non-linear features of atmospheric states. They easily allowthe addition of covariables (such as other weather variables, seasonal or geographic predictors) by a self-selection of the mostuseful predictors for the regression. Moreover, we do not make assumptions on the distribution of the variable of interest. This new approachoutperforms the existing methods for variables such as surface temperature and wind speed.For variables well-known to be tricky to calibrate, such as six-hours accumulated rainfall, hybrid versions of our techniqueshave been created. We show that these versions (and our original methods) are better than existing ones. Especially, they provideadded value for extreme precipitations.The last part of this thesis deals with the verification of ensemble forecasts for extreme events. We have shown several properties ofthe Continuous Ranked Probability Score (CRPS) for extreme values. We have also defined a new index combining the CRPS and the extremevalue theory, whose consistency is investigated on both simulations and real cases.The contributions of this work are intended to be inserted into the forecasting and verification chain at Météo-France
Tournadre, Benoît. "Heliosat-V ˸ une méthode polyvalente d’estimation du rayonnement solaire au sol par satellite." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLM063.
Solar irradiance at the surface of the Earth is recognized as an essential climate variable by the World Meteorological Organization. Its knowledge is as much important for climate sciences as for the development of energy alternatives to fossil fuels, like solar photovoltaic. Ground measurements of this radiation are very sparse on Earth, explaining the interest for satellite-based remote sensing to estimate it. Combining estimations from different satellites in orbit is a pathway to cover the information on the whole globe. Different generations of satellites also produced a multidecadal imagery of the Earth, making it conceivable to estimate long time series of solar radiation, or even to identify long-term variations, a recurrent objective in the study of climate change. For more than 30 years, Heliosat methods estimate surface solar irradiance from satellite imagery, but they have been designed to be applied to a specific sensor on a geostationary orbit, and have limitations in their scope : the need for a long archive of satellite imagery (Heliosat, Heliosat-2), or else the need for multispectral measurements (Heliosat-4). This work dedicated to the development of a Heliosat-V method brings elements of versatility to the satellite-based estimation from so-called "cloud-index" methods, with the ultimate goal to reach homogeneous data of solar radiation derived from measurements made by different satellite instruments. Two issues are in particular considered here to reach such an estimation: the diversity of sensors in terms of spectral sensitivities, and the influence of viewing and solar geometries on spaceborne measurements. The method extensively deals with radiative transfer modeling in the spectral range 400-1000 nm to simulate on one hand satellite measurements in clear-sky conditions, and on the other hand satellite measurements in the presence of an optically thick cloud. The method is tested on the imagery of a geostationary satellite instrument, Meteosat-9/SEVIRI, and in a more exploratory way, on the non geostationary sensor DSCOVR/EPIC. Results are compared to high quality ground-based measurements of irradiance, and show performances similar to operational satellite products. However, the quality of estimates depends on the spectral channel used, and especially of the presence of clear-sky atmospheric scattering or absorption in the signal measured by the satellite instrument. The accent is also put on the need for an accurate absolute calibration of satellite radiometric measurements in order to produce time series of surface solar irradiance with the smallest biases and temporal drift possible
Ginoux, Paul. "L'impact de l'activité humaine sur la composition chimique de la troposphère au-dessus de l'Océan Pacifique: développement d'un modèle téléscopique de chimie et de transport atmosphériques et interprétation des résultats de la campagne de mesure MLOPEX." Doctoral thesis, Universite Libre de Bruxelles, 1997. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212164.
De manière à mieux comprendre l'impact des émissions anthropiques sur la troposphère reculée, les concentrations d'un nombre important de composés atmosphériques ont été mesurés dans la troposphère libre au-dessus d'Hawaii durant la campagne Mauna Loa Observatory Photochemistry Experiment (MLOPEX) accomplie au cours des années 1991 et 1992. Le constituant chimique fondamental pour évaluer cet impact est le radical hydroxyle OH qui fut mesuré au printemps et en été de l'année 1992. La variation diurne de la direction du vent génère pendant la journée un mélange des masses d'air de la couche limite planétaire avec la troposphère libre. Actuellement les modèles régional et global de chimie troposphérique ne peuvent tenir compte à la fois du transport à grande échelle et du mélange local. Nous avons développé un modèle tridimensionnel qui nous permet d'analyser la chimie et la dynamique troposphérique à ces deux échelles. Pour ce faire, nous avons utilisé une grille non-structurée qui offre un moyen efficace de caractériser la région d'Hawaii à l'aide d'une haute résolution et le restant de l'hémisphère Nord avec une résolution qui décroît au fur et à mesure que l'on s'éloigne d'Hawaii. La distribution de 46 composés gazeux avec 138 réactions, incluant une chimie détaillée des hydrocarbures non-méthaniques (isoprène, éthane, éthène, propène et alpha-pinène) est calculée avec un pas de temps de 20 minutes. A l'aide de notre modèle nous avons simulé une période de huit jours pour chacune des saisons. Les résultats des simulations ont été comparés aux observations et interprétés à l'aide d'études de rétro-trajectoires, de traceurs passifs et de bilans chimiques local et régional de l'ozone et de ses précurseurs.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
Molinié, Gilles. "Le rôle de la précipitation dans les échanges électriques entre le nuage d'orage et le sol." Toulouse 3, 1998. http://www.theses.fr/1998TOU30258.