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Literatura académica sobre el tema "Isotopes stables de la vapeur d'eau"
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Artículos de revistas sobre el tema "Isotopes stables de la vapeur d'eau"
Montoroi, J. P., O. Grünberger y S. Nasri. "Utilisation de l'hydrochimie d'un bassin versant de lac collinaire tunisien pour l'étude de la recharge de la nappe alluviale". Revue des sciences de l'eau 17, n.º 2 (12 de abril de 2005): 245–63. http://dx.doi.org/10.7202/705533ar.
Texto completoTesis sobre el tema "Isotopes stables de la vapeur d'eau"
Hamperl, Jonas. "Development of a differential absorption lidar for remote sensing of water vapor and the isotopologue HDO". Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS477.
Texto completoObservations of stable water isotopologues in the atmosphere provide valuable insights into the condensation and evaporation history of water vapor. The provision of such data with sufficient vertical resolution in the lower troposphere (0–3 km) helps to improve our understanding of basic processes like cloud formation, moist convection and mixing, and offers the potential to increase the accuracy in the predictions made by atmospheric general circulation models. Despite the progress in remote sensing from the ground and from space, retrievals from passive sensors are prone to biases and lack the vertical resolution required for water cycle studies in the lower troposphere. The aim of this thesis is to investigate an active remote sensing approach based on the differential absorption lidar (DIAL) method to measure both the water vapor main isotopologue H2(16)O and the semiheavy water isotopologue HD(16)O with high vertical and temporal resolution (100–200 m, 10 min). The expected performance of such an instrument in terms of random and systematic errors was first analyzed using simulations accounting for instrumental and atmospheric parameters. The theoretical analysis showed that the spectral range around 1.98 μm is suitable for DIAL profiling of H2(16)O and HD(16)O and that range-resolved measurements require a tunable laser in that wavelength range with pulse energies of tens of mJ. To fulfill this requirement, a parametric laser source based on a nested-cavity optical parametric oscillator and an optical parametric amplification stage using state-of-the-art high-aperture (5×7 mm^2) periodically poled potassium titanyl phosphate (PPKTP) crystals was implemented. It delivers widely tunable (1.95–2.30 μm) single-frequency radiation with energies up to 9 mJ for 12 ns pulses at a repetition rate of 150 Hz. Using the developed laser source, DIAL measurements of H2(16)O and HD(16)O in the atmospheric boundary layer were conducted in direct-detection mode in the frame of several measurement campaigns. It was shown that with the developed lidar setup, isotopologue measurements with meaningful precision are limited to the first few hundred meters above the ground. To achieve measurements with range resolution and precision suitable for water cycle studies within the entire boundary layer, further instrumental improvements in terms of laser energy and reduced detection noise are necessary. For this purpose, a further step is proposed for the design and pre-development of a lidar setup capable of achieving a higher sensitivity thanks to an optimized double-stage amplification scheme for the laser transmitter that should allow to reach output energies >40 mJ
Bariac, Thierry. "Les Isotopes stables, ¹⁸O, ²H, de l'eau dans continuum sol-plante-atmosphère conséquence pour la vapeur d'eau atmosphérique /". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37611516k.
Texto completoBariac, Thierry. "Les isotopes stables (**(18)o, **(2)h) de l'eau dans le continuum sol-plante-atmosphere : consequence pour la vapeur d'eau atmospherique". Paris 6, 1988. http://www.theses.fr/1988PA066040.
Texto completoTremoy, Guillaume. "Etude de la composition isotopique (deutérium et oxygène 18) de la vapeur d'eau à Niamey (Niger) : vers une meilleure compréhension des processus atmosphériques en Afrique de l'Ouest". Versailles-St Quentin en Yvelines, 2012. http://www.theses.fr/2012VERS0057.
Texto completoWater stable isotopes are a useful tool to investigate past and present-day atmospheric water cycle. If the isotopic composition (δ18O, δD) of tropical precipitation is strongly affected by convective processes at different timescales, large uncertainties remain in the understanding of its variabilty, since a variety of factors can control δ, from local to large-scale processes. One way to better understand the atmospheric controls on the isotopic composition of precipitation is to monitor that of the water vapor in parallel. The goal of this thesis is to monitor continuously for the first time the near-surface water vapor isotopic composition in the Sahel region, and second to study what is the added value of such measurements for investigating the atmospheric water cycle of the West African Monsoon. First, we present our measurement protocol, through several experimental results conducted in laboratory. We have set up a commercially available laser instrument in Niamey (Niger) and monitored the isotopic composition of water vapor during more than two years. Then, we present and discuss the data, through several temporal scales of variability. We show that the water vapor isotopic composition is strongly impacted by convection during the monsoon period, and large-scale dynamics during the dry season. It also records strong intraseasonal fluctuations that could be linked to convection modes of variability during the monsoon, and interactions between atmospheric circulation and tropical/extratropical teleconnections during the dry season. We also discuss diurnal variations, and investigate the variability at the scale of the rain events
Hette, Tronquart Nicolas. "Organisation trophique des peuplements piscicoles des cours d'eau : approche par l'analyse des isotopes stables". Paris, Muséum national d'histoire naturelle, 2012. http://www.theses.fr/2012MNHN0022.
Texto completoPerga, Marie-Elodie. "Origines et flux de carbone en lacs : étude par analyse de la composition en isotopes stables du carbone et de l'azote du zooplancton et des poissons". Chambéry, 2004. http://www.theses.fr/2004CHAMS031.
Texto completoFish communities occupy the top of food chains. How fish obtain their constitutive carbon depends consequently of all the carbon pathways at the downer levels of the food web. This trophic position confers to fish a potential role of integrators of the underlying processes, at the ecosystem scale. Moreover, stable isotopes composition of an organism depends on all the pathways that transfer carbon up to this organism. Consequently, we wondered in what extent the stable isotopes composition of fish could be a proxy of the trophic functioning of lakes. To address this assumption, whitefish, Coregonus lavaretus, a zooplanktivorous salmonid common in alpine lake, was, in a first time, used as biological model. A preliminary study had revealed the stable isotope composition of whitefish was quite variable among alpine lakes. According to our idea, this variability mirrors differences in the carbon pathways of the food web of these lakes. To understand what was reflected by this variability, we studied initially in what extent it resulted from intrinsic factors (such as lake size or trophic status). This study has then lead us to deepen the role played by the zooplankton compartment in carbon pathways up to Whitefish. In the final stage of this first part, the isotopic composition of whitefish appeared as a proxy for lake trophic functioning. Changes in environmental factors can alter carbon pathways in food webs. If fish are efficient integrators of carbon pathways, impacts of perturbations should be mirrored on their isotopic compositions. Impacts of two anthropogenic perturbations of stable isotope composition of fish were then evaluated : the first one relates to eutrophication - restoration of two alpine lakes, the second one to water levels changes in two Malian reservoirs. Results from these two studies reveal that major changes, ensuing from these perturbation, in carbon origins and fluxes within lake food webs are recorded in the isotopic history of fish communities
Kessaci, Saidh. "Applications des méthodes de traçage isotopiques (18O,2H) et chimiques pour l'étude des transferts d'eau par ruissellement : investigations à l'échelle de petites parcelles". Paris 6, 2003. http://www.theses.fr/2003PA066446.
Texto completoColin, Kaczala Claudine. "Profils isotopiques(¹⁸O et ²H) de fluides (eau liquide, vapeur et CO₂) de la zone non saturée sous climat désertique : application à l'évaluation de l'évaporation des nappes libres au Sahara nord-occidental". Paris 11, 1986. http://www.theses.fr/1986PA112204.
Texto completoThis work presents isotope profiles (18O and 2H) of liquid water, water vapor and CO₂ established on five boreholes made in the unsaturated zone at Béni-Abbès (Algeria). One preparation line of water micro quantities for deuterium and oxygen 18 analyses was built, and special devices for soil gases and very dry sands sampling were utilized. The results allowed the study of: -relationships between the O contents in liquid H₂¹⁸O, water vapor and CO₂, -relationships between ¹⁸O and ²H for liquid water and vapor, -Application of isotopic model for evaporation of Barnes et al. (1984) to three profiles, -One chloride profile. As a conclusion, some assessments were made about isotopic equilibrium between the different fluids in soil and about recharge water and evaporation rates calculated in three locations
Gajurel, Ananta Prasad. "Etude sédimentologique et géochimique (isotopes stables) des bassins synorogéniques de l'Hymalaya du Népal (Siwaliks et bassin de Kathmandu)". Université Joseph Fourier (Grenoble), 2006. http://www.theses.fr/2006GRE10102.
Texto completoThe work deals with paleo-environmental study of the Siwalik foreland basin (upper Miocene) and the intermountain Kathmandu basin (Plio-Pleistocene). O and C composition of modern mollusks and waters of Ganga Plain and intermountain basins were realized as a reference for paleo-environmental study. The δ18O of rivers varies from -18‰ in north of Himalaya to -4‰ in the plain. The δ18Ocar of modern shell show an equilibrium fractionation with the river waters (20 to 25°C). Both carbonate and river water values are different according to catchment basin extension. The δ13CDIC of rivers are higher than δ13Ccar due to organic carbon incorporation in shell. In the Siwaliks, 18Ocar varies from -16. 4 to 0. 6‰. For the Late Miocene, the δ18Ocar values are lower than Pliocene and modern values. Therefore, rivers running through the Siwalik plain should show different geometry. The δ13C show a sharp increase up to 0‰ around 5 Ma, which seems to be linked to the contemporaneous evolution of C4 plant. The Kathmandu Basin (3-0 Ma) is a transported basin and characterized by fluvio-lacustrine sediments. The evolution of lake is controlled by tectonic, landslide and debris-flow. The δ18Ocar older than 1 Ma vary from -11 to -4‰ and are compatible with river water (-10. 1 to -7‰) as well as monsoon water (-18 to 2‰) in Kathmandu. In contrast δ18Ocar of Gokarna Formation (< 50 Ka) is extremely high (-2. 4 to 8‰) and is compatible to dry period meteoric water (-6. 5 to 7. 5‰). Such values are generally associated with diatomite. Two processes could be interacted for diatomite time: reduction in summer precipitation and strong evaporation; both phenomena tend to make a strong concentration in 18O
Leroy-Dos, Santos Christophe. "Variabilité du cycle hydrologique atmosphérique en régions polaires à partir de mesures des isotopes stables de l'eau dans la vapeur, les précipitations et les carottes de névé". Electronic Thesis or Diss., université Paris-Saclay, 2021. http://www.theses.fr/2021UPASJ006.
Texto completoIn a global warming context, understanding the evolution of sea level rise is a major challenge. It is key to estimate the evolution of the atmospheric hydrological cycle in the polar regions, which directly influences the surface mass balance of the Arctic and Antarctic ice caps (the two largest freshwater reservoirs on the planet). Records are available from satellite data for the last 50 years and a few rare weather data since the 50's in Antarctica, but these records are too short to study the patterns of interannual variability and the difference between anthropogenic and natural signals. One of the best ways to access longer records is to use climate proxies in snow cores. The water isotopic composition in these cores is widely used to reconstruct past temperature variations. However, the link between temperature and isotopic composition is not very well constrained because many other parameters influence the isotopic composition of snow at the time of its formation (i.e. temperature, altitude, humidity, origin of the air mass) or after snow deposition on the surface (i.e. atmosphere-snow exchange, signal scattering, sublimation of surface snow).The objective of this thesis is to better understand the atmospheric hydrological cycle and its influence on the isotopic composition of vapour and precipitation in polar regions with the idea of improving the interpretation of snow core records in these regions. This work is divided into 3 parts.Firstly, we developed a technical solution to meet the challenge of measuring the vapor isotopic composition all year round in polar regions. Indeed, winter being very dry in these regions (down to 10 ppmv at Dome C in winter), the use of a Picarro laser analyzer is limited because it is very sensitive to humidity variations below 2000 ppmv. Winter is a key season in the polar regions as it is associated with significant climate variability due to numerous synoptic events. During this thesis, the fabrication of 2 prototypes of low humidity level generator (LHLG) allowed the calibration of the Picarro analyzers over a range of 200 to 2500 ppmv.Then, I analyzed the longest series of vapor and precipitation isotopic composition measurements ever performed in a polar region: 4.5 years continuously at 78°N in Svalbard. I showed that the water isotopic composition at this measurement site was unsignificantly influenced by local processes. Thanks to this, I was able to attribute the observed winter variability to synoptic events and thus assign a different isotopic signature to the air masses according to their origin (North Atlantic or Arctic).Finally, I installed the new calibration instrument (LHLG) built at the beginning of my PhD at Dumont D'Urville (DDU), on the coast in Terre Adélie. Thanks to this, the first continuous measurement campaign of the vapor isotopic composition at DDU initiated in January 2019 is still ongoing. I present here the first 22 months of this new record. This unique series makes possible to document the isotopic signature of the atmospheric hydrological cycle in Terre Adélie all year round. I have studied the influence of katabatic winds, sea ice and atmospheric rivers on the signal recorded in the vapor. These preliminary results open perspectives for the interpretation of recently drilled cores from the ASUMA program