Дисертації з теми "Couche limite atmosphérique (ABL)"
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Nishio, Yoshiyuki. "Challenges in applying the PSPG/SUPG Finite element method to the atmosphéric boundary layer." Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS017.
In the context of a Chemical, Biological, Radiological, and Nuclear (CBRN) application for the Belgian Defense, the original objective of the work was to simulate a realistic open-air CBRN case (e.g. dispersion after an explosion of particles in a city), by applying the Streamline-Upwind Petrov-Galerkin (SUPG) stabilization on a nite element method (FEM), together with a second phase (i.e. particles). This would be done through the code Cool uid 3, a Domain Speci c Language (DSL) written in C++.However, open-air applications requires to describe the atmospheric bound-ary layer (ABL) correctly. This has never been done using stabilized FEM. Consequently, the challenge of this work is to answer the simple question: How to model an ABL taking advantage of the SUPG stabilization method.To reduce the number of elements produced by a wall-resolved simulation, the ABL was implemented with a wall model and veri ed in 2D, while a few corrections (e.g. grid scalability, stable velocity pro le) could also be adressed.However, the 3D implementation revealed spurious oscillations, suggesting a numerical origin. Although SUPG does provide dissipation, it seemed not su cient enough for such a high Reynolds ow. Consequently, two directions were followed to add numerical dissipation: Firstly, the implementation of an extended version of the SUPG, the Variational MultiScale method (VMS), was initiated. The latter provides a combined framework for stabilization and turbulence modeling. Secondly, two LES formulations, known for their dissipative behavior, were integrated.Having solved the spurious oscillations, the velocity pro le was analyzed. Eventually, the viscous Reynolds number for the ABL domain was reduced to enable the comparison with an available DNS result. Fortunately, rela-tive to the standard no-slip wall condition and to the friction velocity condi-tion, the wall model implementation provided the best result, although not matching.In conclusion, we ascertained two methodologies (LES and SUPG / VMS) that have the potential to approach the ABL ow. The stabilized FEM using SUPG revealed that it is currently not su cient to avoid spurious oscillations in the case of an ABL ow. In contrast, LES provided encouraging results for reduced Reynolds number, supporting that some kind of turbulence model is indispensable. This emphasizes that the implementation of VMS should be promising, although challenging
Réchou, Anne. "Structure turbulente de la couche limite atmosphérique marine (expérience SOFIA)." Toulouse 3, 1995. http://www.theses.fr/1995TOU30058.
Rodier, Quentin. "Paramétrisation de la turbulence atmosphérique dans la couche limite stable." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30343/document.
The modeling of the stable atmospheric boundary layer is one of the current challenge faced by weather and climate models. The stable boundary layer is a key for the prediction of fog, surface frost, temperature inversion, low-level jet and pollution peaks. Furthermore, polar regions, where stable boundary layer predominates, are one of the region with the largest temperature rise : the stable boundary layer modeling is crucial for the reduction of the spread of climate predictions. Since more than 15 years, the GABLS models intercomparison exercices have shown that turbulent mixing in the stable boundary layer is overestimated by numerical weather prediction models. Numerous models artificially strengthen the activity of their turbulence scheme to avoid a laminarization of the flow at a critical value of the gradient Richardson number. The existence of this threshold is only a theoretical and a numerical issues. Numerous observations and high-resolution numerical simulations do not support this concept and show two different regimes : the weakly stable boundary layer that is continuously and strongly turbulent; and the very stable boundary layer globally intermittent with a highly anisotropic and very weak turbulence. This thesis aims at improving the turbulence scheme within the atmospheric research model Méso-NH developped by Météo-France and the Laboratoire d'Aérologie, and the operational weather forecast model AROME. We use a traditional methodology based on the comparison of high-resolution simulations that dynamically resolve the most energetic turbulent eddies (Large-Eddy Simulations) to single-column simulations. Several LES covering the weakly and the very stable boundary layer were performed with Méso-NH. The limits of applicability of LES in stratified conditions are documented. The first part of the study deals with the overmixing in the weakly stable boundary layer. We propose a new diagnostic formulation for the mixing length which is a key parameter for turbulence schemes based on a prognostic equation for the turbulent kinetic energy. The new formulation adds a local vertical wind shear term to a non-local buoyancy-based mixing length currently used in Méso-NH and in the French operational model AROME. The new scheme is evaluated first in single-column simulations with Méso-NH and compared to LES, and then in the AROME model with respect to observations collected from the operational network of Météo-France. The second part presents a theoretical and numerical evaluation of a turbulence scheme based on two prognostic equations for the turbulent kinetic and potentiel energies. In stratified conditions, the heat flux contributes to the production of turbulent potential energy. The laminarization of the flow is then limited by a reduction of the destruction of the turbulent kinetic energy by a better representation of the anisotropy and a counter-gradient term in the heat flux. On the simulated cases, this new formulation behaves similarly than the scheme with one equation for the turbulent kinetic energy because the self-preservation mechanism is not dominant compared to the dissipation term. Further research should improve the turbulent kinetic energy dissipation closure in the very stable regime
Frangi, Jean-Pierre. "Dynamique de la couche limite de surface sahélienne." Toulouse 3, 1988. http://www.theses.fr/1988TOU30247.
Arduini, Gabriele. "Processus de la couche limite atmosphérique stable hivernale en vallée alpine." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU006/document.
Alpine valleys are rarely closed systems, implying that the atmospheric boundary layer of a particular valley is influenced by the surrounding terrain and large-scale flows. A detailed characterisation and quantification of these effects is required in order to design appropriate parameterisation schemes for complex terrains. The focus of this work is to improve the understanding of the effects of surrounding terrain (plains, valleys or tributaries) on the heat and mass budgets of the stable boundary layer of a valley, under dry and weak large-scale wind conditions. Numerical simulations using idealised and real frameworks are performed to meet this goal. Several idealised terrains (configurations) were considered: an infinitely long valley (i.e. two-dimensional), and upstream valleys opening either on a plain (valley-plain), on a wider valley (draining) or on a narrower valley (pooling). In three-dimensional valleys, two main regimes can be identified for all configurations: a transient regime, before the down-valley flow develops, followed by a quasi-steady regime, when the down-valley flow is fully developed. The presence of a downstream valley reduces the along-valley temperature difference, therefore leading to weaker down-valley flows. As a result, the duration of the transient regime increases compared to the respective valley-plain configuration. Its duration is longest for pooling configuration. For strong pooling the along-valley temperature difference can reverse, forcing up-valley flows from the narrower towards the wider valley. In this regime, the volume-averaged cooling rate is found maximum and its magnitude dependent on the configuration considered. Therefore pooling and draining induce colder and deeper boundary layers than the respective valley-plain configurations. In the quasi-steady regime the cooling rate is smaller than in the transient regime, and almost independent of the configuration considered. Indeed, as the pooling character is more pronounced, the warming contribution from advection to the heat budget decreases because of weaker down-valley flows, and so does the cooling contribution from the surface sensible heat flux. The mass budget of the valley boundary layer was found to be controlled by a balance between the convergence of downslope flows at the boundary layer top and the divergence of down-valley flows along the valley axis, with negligible contributions of subsidence far from the slopes. The mass budget highlighted the importance of the return current above the down-valley flow, which may contribute significantly to the inflow of air at the top of the boundary layer. A case-study of a persistent cold-air pool event which occurred in February 2015 in the Arve River Valley during the intensive observation period 1 of the PASSY-2015 field campaign, allowed to quantify the effects of neighbouring valleys on the heat and mass budgets of a real valley atmosphere. The cold-air pool persisted because of warm air advection at the valley top, associated with the passage of an upper-level ridge over Europe. The contributions from each tributary valley to the mass and heat budgets of the valley atmosphere were found to vary from day to day within the persistent stage of the cold-air pool, depending on the large-scale flow. Tributary flows had significant impact on the height of the inversion layer and the strength of the cold-air pool, transporting a significant amount of mass within the valley atmosphere throughout the night. The strong stratification of the near-surface atmosphere prevented the tributary flows from penetrating down to the valley floor. The evolution of the large-scale flow during the episode had a profound impact on the near-surface circulation of the valley. The channelling of the large-scale flow at night, can lead to the decrease of the horizontal temperature difference driving the near-surface down-valley flow, favouring the stagnation of the air close to the ground
Branchet, Bérengère. "Analyse d'un modèle de couche limite atmosphérique bidimensionnel non-hydrostatique anélastique." Bordeaux 1, 1998. http://www.theses.fr/1998BOR10531.
Tignat-Perrier, Romie. "Facteurs de structuration des communautés microbiennes de la couche limite atmosphérique." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU034.
Up to 106 microbial cells per cubic meter are found in suspension in the planetary boundary layer, the lowest part of the atmosphere. Direct influences of the planetary boundary layer on humans, crops and diverse ecosystems like soils and oceans make the full understanding of its composition, both chemical and microbiological, of utmost importance. While microbial communities of the planetary boundary layer vary significantly at different temporal and spatial scales, they remain largely unexplored. The main goal of this thesis was to understand how airborne microbial communities are structured in the troposphere with special emphasis on the planetary boundary layer and to identify their main controlling factors. We investigated both the taxonomic and functional composition of airborne microbial communities in the dry phase (i.e. not cloud-associated) over time at nine different geographical sites around the world using high throughput sequencing technologies.Our investigation that focused on microbial taxonomy showed that local landscapes were the main contributors to the global distribution of airborne microbial communities despite the potential occurrence of long-range transport of airborne microorganisms. We also observed that meteorology and the diversity of the surrounding landscapes played major roles in the temporal variation of the microbial community structure in the planetary boundary layer. We further explored the temporal variation of airborne microbial communities at a continental and mountainous site in France (1465 m above sea level) over a full-year. This study demonstrated the importance of the surface conditions (i.e. vegetation, snow cover etc.) of the surrounding landscapes on the taxonomic composition of airborne microorganisms. The seasonal changes in agricultural and vegetated areas, which represented a significant part of the site’s surrounding landscape, were correlated to the shifts in the taxonomic composition of airborne microbial communities during the year. Finally, we investigated the functional composition of microbial communities of the planetary boundary layer to identify whether the physical and chemical conditions of the atmosphere played a role in selection or microbial adaptation of airborne microorganisms. The comparative metagenomic analysis did not show a specific atmospheric signature in the functional potential of airborne microbial communities. To the contrary, their functional composition was mainly correlated to the underlying ecosystems. However, we also showed that fungi were more dominant relatively to bacteria in air as compared to other (planetary bound) ecosystems. This result suggested a selective process for fungi during aerosolization and/or aerial transport and that fungi might likely survive aerosolization and/or aerial transport better than bacteria due to their innate resistance to stressful physical conditions (i.e. UV radiation, desiccation etc.). Our results provide a clearer understanding of the factors (i.e. surrounding landscapes, distant sources, local meteorology, and stressful physical atmospheric conditions) that control the distribution of microbial communities in the atmospheric boundary layer. Our investigations provide a basis for further studies on the prediction and even control of airborne microbial communities that would be of interest for public health and agriculture
Zegadi, Rabah. "Contribution à l'étude de la couche de surface atmosphérique, en situation stable, simulée en soufflerie." Ecully, Ecole centrale de Lyon, 1991. http://www.theses.fr/1991ECDLA012.
Mathieu, Anne. "Analyse synoptique de la couche limite atmosphérique marine pendant la campagne sémaphore." Paris 6, 2000. http://www.theses.fr/2000PA066315.
Delboulbé, Eric. "Simulation numérique des écoulements de couche limite atmosphérique autour de structures bâties." Aix-Marseille 2, 1997. http://www.theses.fr/1997AIX22070.
Hallali, Ruben. "Variabilité de la réfractivité dans la couche limite atmosphérique par observation radar." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV083/document.
Weather radars can retrieve refractivity changes based on phase variations of stationary targets. These retrievals provide valuable information of moisture in the atmospheric boundary layer along the radar path. Recent work on errors associated with these retrievals has shown that the refractivity variability is stronger during the afternoon and the summer season. This observation has led us to study further the link between the refractivity variability measured by radar and the small scales atmospheric fluctuations. First, we compared the variability of the refractivity retrieved from operational weather radars operating at C-band (5.6 GHz) to the variability of the refractivity directly measured by Automatic Weather Stations (AWS). A strong correlation between the two measurements was shown with a negative bias increasing with range from the radar. The bias is well explained when the variability signal is strong if one considers the model of a frozen turbulence transported by the wind. In winter, the measured variability was weaker and close to quantization noise of the AWS measurements, so it was more difficult to draw thesame conclusions. Overall, we were able to demonstrate qualitatively and quantitatively that the refractivity variability retrieved using the radar observations and measured by AWS stations is due to low-level coherent turbulent structures. Next, in order to obtain information at hectometre’s scales, a dedicated field campaign was conducted at SIRTA atmospheric observatory, near Paris. From June to September 2014 two radars (a 94 GHz W-band and a 9.5 GHz X-band radar) were pointing horizontally toward four corner reflectors aligned along a 700 meters line. Two wind and humidity high frequency measurement towers were deployed near the targets. Inter-comparisons between radar and in-situ refractivity measurement also showed a very good correlation. We finally demonstrated the possibility to compute radar refractivity on the path between two targets separated by 50 to 350 m and used this measure of the local variability of the refractivity to identify boundary processes linked to low level atmospheric turbulence
Darbieu, Clara. "Processus turbulents dans la couche limite atmosphérique pendant la transition d'après-midi." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30326/document.
This thesis focuses on the afternoon transition (AT) of the atmospheric boundary layer (ABL). This transitional period is complex, because it is non-stationary and most of the forcings, though smaller than during the previous convective period, may come into play. Thus, this transitional period is less understood than the quasi-stationary convective, neutral or stable regimes. Yet, the AT could impact on the nocturnal fog set up, influence the boundary-layer development on the following day and play a crucial role in the transport and dispersion of pollutants and trace species towards the free troposphere. Therefore, a better understanding of the AT could improve the meteorological models. One of the main objectives of the thesis is to improve the knowledge of the decay of turbulence during the AT, when the surface energy transfers are gradually decreasing. We especially put emphasis on the evolution of the ABL turbulence vertical structure. This work is in the core of the BLLAST (Boundary Layer Late Afternoon and Sunset Turbulence) international project. A field campaign took place in summer 2011 in France, on the northern side of the Pyrenean foothills (at "Plateau de Lannemezan"), providing numerous observations used in the thesis. In addition, we also used a Large-Eddy Simulation (LES) with which the turbulent scales can be explicitly resolved. Thanks to this approach, the evolution during the AT of the scale definitions, scaling laws, turbulence characteristics and of the role of the boundary layer processes are now better understood. Thanks to the set of observations, an overview of the BLLAST ATs has been done, according to the various meteorological conditions as well as the structure and evolution of the mean and turbulence structure of the ABLs. A large variability of the AT duration was observed, depending on the surface characteristics and atmospheric conditions. The evolution of the turbulent characteristics during the AT has been studied at the surface and higher in the ABL by means of aircraft measurements and LES data. The study points out the LES ability to reproduce the turbulence evolution throughout the afternoon
Buty, Didier. "Paramétrisation de la turbulence atmosphérique dans un code méso-météorologique tridimensionnel et non-hydrostatique." Lyon 1, 1988. http://www.theses.fr/1988LYO10104.
Jacoby-Koaly, Sandra. "Application d'un radar profileur de vent UHF à l'étude de la couche limite atmosphérique." Toulouse 3, 2000. http://www.theses.fr/2000TOU30144.
Idé, Hassane. "Dynamique et turbulence dans la couche limite atmosphérique de surface sahélienne (expérience STARS)." Toulouse 3, 1991. http://www.theses.fr/1991TOU30124.
Boilley, Alexandre. "Modélisation de cisaillements de vent et assimilation de données dans la couche limite atmosphérique." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00638822.
Girard-Ardhuin, Fanny. "Utilisation d'un radar UHF RASS pour l'étude de la couche limite atmosphérique en vue d'une application à la pollution atmosphérique." Toulouse 3, 2001. http://www.theses.fr/2001TOU30092.
Lambert, Dominique. "Structure moyenne et turbulente de la couche limite atmosphérique au dessus de l'océan (expérience SEMAPHORE)." Toulouse 3, 1997. http://www.theses.fr/1997TOU30178.
Blein, Sébastien. "Observation et modélisation de couche limite atmosphérique stable en relief complexe : le processus turbulent d'écoulement catabatique." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI023/document.
The stable atmospheric boundary layer, particularly in complex terrain, is not yet fully understood and it is thus still inadequately modelled. A surface cooling of a sloping terrain generates katabatic wind due to local density increase. This flow behaves as a wall-bounded turbulent jet, often simply modelled by a local balance between the buoyancy force and the turbulent friction. In mountainous regions, the wind maximum is typically observed at a height (z_j) of 1-10 m above the ground. The wall-bounded jet is responsible for a momentum-flux sign change and a heat-flux variability close to the ground. Those turbulent-flux variabilities are fully conflicting with the aplicability of the Monin-Obukhov similarity theory (MOST), which is nevertheless universally used in the atmospheric models to provide the surface boundary condition. If the MOST is already questionable for the very stable cases, it is obviously not valide over sloping surfaces because it neglectes the coupling of the wind and temperature equations, which constitutes the katabatic source. Hence, it is not possible to adequatly model a katabatic flow (z_j O(1m)) using the MOST, especially with a vertical resolution of the order of magnitude of z_j. The aim of the this PhD work is thus to improve the current understanding and modelling capacity of the katabatic winds.Since data sets of turbulent-katabatic-flow measurements are still scarce, a new field campain was carried out on a steep slope (20-40 deg): the west face of the Grand-Colon mountain (Belledonne ridge, French Alps). The experimental setup was mainly composed of a 6m mast with four sonic-anemometer levels (1, 2, 4 and 6m) to measure the turbulence on both sides of the katabatic jet. The spectral analysis shows the hight sensitivity of the local flow to external perturbations, even when these are weak. The hight-frequency subrange shows a classical behaviour (energy-injection frequency, inertial subrange), but the spectra of the intermediate and low-frequency subranges are less typical: turbulent perturbations with an energy of the order of magnitude of the local injection are present. A specific cospectra behaviour of the katabatic flows is shown: negative and positive cross-correlations overlap gradually, increasing z. The MOST fails in representing the observed flow and a surface-flux alternative estimation is succesfully used to describe the friction vellocity.The 1D surface model of ISBA (Météo-France) is modified to model katabatic flows. The model is firstly validated with a standard calibrated Prandtl model (with variable eddy difusivity). Secondly, the field data are modelled both with a prescribed effective diffusivity (from data) and using the 1.5-order turbulence scheme. The mean velocity and temperature fields are well reproduced, but it appears that the model is over-diffusive (which generates excessive fluxes), even when an adapted mixing-length is used.Realistic 3D LES simulations (Meso-NH, Météo-France) are computed with high resolution to model the field data. Spatial flow variabilities over sloping terrain are finely represented, but are biased, mainly due to the using of MOST for the surface boundary counditions. The using of MOST shifts the start of the katabatic source detection by the atmospheric model to a height of 2 m, while the katabatic source reaches its maximum at the surface. Analytical katabatic models (of the Prandtl type, which could be easily used to feed surface boundary counditions) need an "apriori" definition of the eddy and heat diffusivities. Currently, the general definition of these diffusivities is only possible by the use of turbulent models that include closures. The coupling of the previously-presented 1D surface model (validated off-line) is suggested to overcome the lack of physics description in the classic surface boundary counditions. Preliminary work on this coupling is developed and perspective solutions are proposed
Canut, Guylaine. "Interaction mousson-Harmattan, échanges de petite échelle." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1194/.
Entrainment of dry air from the Harmattan flow inside the moist monsoon flow is a turbulent process. This process is analysed in the context of the AMMA (African Monsoon Multidisciplinary Analysis) campaign experiment, which aimed at better understanding and forecasting the African Monsoon. The atmospheric measurements made by the ATR-42 research aircraft, and large eddy simulations enable us in a complementary way to study the mean and turbulent vertical structure of the sahelian boundary layer, to describe the dry intrusions and their contributions in the turbulent transferts, to quantify the entrainment process, to test the existing parametrizations and to link the entrainment process with the conditions, and with the characteristics of the boundary layer and its interfaces, in particular the windshear between monsoon & Harmattan
Dipankar, Anurag. "Simulation des grandes échelles de la turbulence atmosphérique : application à l’étude de la propagation des ondes électromagnétiques dans la couche limite atmosphérique." Paris 6, 2010. http://www.theses.fr/2010PA066029.
Pergaud, Julien. "Étude et paramétrisation de la turbulence et des nuages de couche limite." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/2340/.
The main objective of this thesis was to develop a new parameterization enabling to improve the mixing and representation of clouds in convective boundary layers. We thus developed a parameterization based on the concept EDMF for Eddy- Diffusivity/Mass Flux and in which the mass _ux scheme represents idealized thermal which can exchange air with its environment and whose air parcels can condensate. In the dry part of the updraft, entrainment and detrainment are defined as proportional to the buoyancy and inversely proportional to the vertical velocity in the updraft. This formalism allows the exchanges to adapt depending on the type of boundary layer or the intensity of convection. In the cloud, the buoyancy sort formalism was chosen. Indeed, it is well suited to represent exchanges between the cloud and its environment. Tests in a single column model helped highlight the contribution of such a scheme in the representation of the turbulence but also boundary layer clouds. It allows a good representation of the counter-gradient area and corrects a well-knwon defect of eddy-diffusivity parameterizations. 3D results are presented and demonstrate the need for such a scheme for models with 2. 5km resolution. It has been well implemented in the new operational mesoscale model at Météo-France named AROME
Puygrenier, Vincent. "Etude de la couche limite atmosphérique côtière durant ESCOMPTE 2001 : évaluation et amélioration des performances d'un radar UHF." Toulouse 3, 2005. http://www.theses.fr/2005TOU30193.
Forecasting of pollution events was the main objective of the ESCOMPTE-2001 campaign, which took place in the Marseille/Fos/Berre heterogeneous area (southeastern France) in the early summer 2001. This goal requires good understanding and taking into account, by physicochemical numerical models, of the physical processes in the Atmospheric Boundary Layer (ABL), in which pollutants are emitted, transported and diffused. In the ESCOMPTE-2001 campaign context, this work was devoted to study the low troposphere during sea breeze events, related to meteorological conditions responsible for poor air quality of coastal areas. It presents notably an oscillation of the sea breeze intensity and competitions of locals and regional sea breeze, which change the advected time of the marine air above the continental surface and thus influence the ABL development and its pollutants concentration. This study is based principally on the network of four UHF wind profilers radars set up on the coastal area of Marseille/Fos/Berre, allowing a continuous three-dimensional description of the sea breeze flow and the ABL. For the needs of this phenomenological work, methodological developments was realized to improve the measurement of ABL turbulent properties with UHF radars (terms of turbulent kinetic energy budget) and the use of wind profilers network for the study of pollutants plumes trajectography
Durand, Pierre. "Approche expérimentale de la dynamique de la couche limite atmosphérique pour des conditions de surface non homogènes." Toulouse 3, 1989. http://www.theses.fr/1989TOU30124.
Puygrenier, Vincent. "Etude de la couche limite atmosphérique côtière durant ESCOMPTE 2001. Evaluation et amélioration des performances d'un radar UHF." Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00011691.
Dans le cadre de la campagne ESCOMPTE-2001, ce travail de thèse est consacré à l'étude de la basse troposphère en période de brise de mer, situation météorologique défavorable à la qualité de l'air des zones côtières. Il a permis notamment de mettre en évidence une oscillation de l'intensité de la brise de mer et des compétitions de brises de mer locales et régionales, qui modifient le temps d'advection de l'air marin sur la surface terrestre et ont donc des répercussions importantes sur le développement de la CLA et sa concentration en polluants. Ces travaux s'appuient principalement sur le réseau de quatre radars profileurs de vent UHF mis en place sur la zone côtière de Marseille/Fos/Berre, permettant une description en trois dimensions et en continu dans le temps des écoulements de brises de mer et de la CLA.
Pour les besoins de cette étude phénoménologique, des développements méthodologiques sont apportés sur la mesure des propriétés turbulentes de la CLA par les radars UHF (termes du bilan de l'énergie cinétique turbulente) et sur leur utilisation en réseau pour l'étude de la trajectographie de panaches de polluants.
Bernard-Trottolo, Sandrine. "Diagnostic de la présence de structures cohérentes au sein de la couche limite atmosphérique : campagnes TRAC98 et MAP99." Toulouse 3, 2001. http://www.theses.fr/2001TOU30182.
Kubwimana, Thierry. "Simulation de l'écoulement atmosphérique au voisinage d'une tête de tunnel." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEC023.
The design of a mechanical ventilation system in a tunnel requires to identify all the physical phenomena involved in the movement of the air in the tunnel. That is in order to establish the necessary ventilation capacities with regard to regulatory objectives. Atmospheric effects feature among the mechanisms likely to generate overpressures or depressions near the openings of a tunnel and consequently to induce or to modify the airflow established inside. This research work intends to contribute to a better understanding as well as a better consideration of the external atmospheric effects in tunnel ventilation studies.Experimental and numerical modeling have been completed. Wind tunnel tests were carried out in the atmospheric wind tunnel of the École Centrale de Lyon and used different techniques (PIV, hot wire anemometry, micromanometer) to measure the mean and turbulent statistics of the atmospheric flow in the vicinity of a tunnel. Time averaged (RANS) and filtered (LES) turbulence models were also used to simulate the atmospheric flow around a tunnel.The suitable representation of the unsteady turbulent atmospheric flow at the inlet of an LES computational domain remains an issue. During this work, we implemented a synthetic turbulence generator in the CFD code Fluent and, through comparison with experimental data, derived the optimal setup for the simulation of a fully rough atmospheric boundary layer.Thereafter, two tunnel configurations were studied by numerical and experimental means. In a first series of tests, the pressure field at the front section of a rectangular cavity was studied. The comparisons between the different approaches highlighted the influence of the geometry of the tunnel and the arrangement of the surrounding urban-like environment, as well as a better performance of the LES model in the description the turbulent flow. And in a second series of tests, we got closer to a realistic configuration and instrumented an open tunnel in which we could create an airflow directed towards the outside or the inside of the structure. The results showed a significant interaction between the atmospheric boundary layer and the three-dimensional wall jet from the tunnel
Sandu, Irina. "Impact de l'aérosol sur le cycle de vie des nuages de couche limite." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/116/.
Anthropogenic aerosols may have a noticeable impact on the life cycle of boundary layer clouds, via their effects on radiation and precipitation efficiency. It is however difficult to document such impacts from observations. The interactions between aerosol particles and the dynamics of boundary layer cloud systems (typically marine stratocumulus) have therefore been explored with high resolution numerical models (LES), that now include detailed parameterizations of turbulence, radiative transfer and microphysics. In this study, the focus is on the coupling between aerosol impacts on cloud microphysics and the diurnal cycle of stratocumulus clouds. LES simulations of a 36 hours cycle are performed with aerosol concentrations typical of pristine and polluted air masses, successively. Although the simulations start from the same initial state, they rapidly diverge. The increased concentration of cloud condensation nuclei yields to an increased droplet concentration, a reduction of the droplet sizes and the inhibition of the droplet sedimentation and precipitation formation. The liquid water content at cloud top hence increases and the cloud top entrainment is strengthened. Moreover, the absorption of solar radiation at cloud base is no longer balanced by the droplet and drizzle evaporation, and the decoupling of the cloud layer is reinforced. Overall, the polluted cloud layer is better coupled during the night and more decoupled during the day than its pristine counterpart. Measurable signatures of these impacts are identified to help at designing observational studies of aerosol impacts on the dynamics on boundary layer clouds
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.
Colin, Pierre-Yves. "Evaluation numérique et expérimentale des effets de la structure de la végétation sur l'écoulement de la couche de surface atmosphérique." Aix-Marseille 2, 2005. http://theses.univ-amu.fr.lama.univ-amu.fr/2005AIX22100.pdf.
The additional terms appearing when one average the Reynolds equations are analysed. Explicit simulations founded on these equations are carried out on simplified foliages. These simulations give the aerodynamic drag, the production and the dissipation ε of the turbulent kinetic energy k. Implicit simulations are carried out on the same foliages represented by the addition in the equations of terms provided by explicit simulations or by the literature. In the first case, the field of the average horizontal component U is well represented, that of k is less good. In the second case, the source terms must be adjusted using coefficients which depend on the foliage. The reintroduction of the scale length in the equation of ε improve simulations. Experimental measurements are carried out in forest edge and are compared with simulations, which describe the field of U well but fail to represent the field of k
Brosse, Fabien. "Influence de la couche limite convective sur la réactivité chimique en Afrique de l'Ouest." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30324/document.
This thesis focuses on the influence of the convective and cloudy boundary layer on the chemical reactivity in West Africa. To answer this question, high resolution simulations (50m) are performed on the atmospheric model Meso-NH coupled to a detailed chemical scheme representing the gaseous and aqueous phases. This spatial scale allow to explicitly represent the spatial and temporal characteristics of turbulent structures. Thermals in the boundary layer are identified by a conditional sampling based on a radioactive-decay passive scalar. The turbulent transport influence on the redistribution of chemical species depends on the chemical lifetimes of these species. Spatial segregation is created within the convective boundary layer that increases or decreases the mean reaction rates between compounds. AMMA campaign field study, and more recently DACCIWA, are used to define dynamical and chemical forcing of two simulated environments. The first one is representative of a biogenic environment dominated by natural emissions of VOC. The second reproduces a moderately polluted typical urban area of the Guinean Gulf (Cotonou in Benin). For the sake of simplicity, simulations analysis are limited to the chemical reaction between isoprene and OH in the biogenic case, and the reaction between C>2 aldehydes and OH in the anthropogenic case. The convective boundary layer influence is studied at thermal and domain scale. This makes the connection with coarse resolution models for which a hypothesis of perfect and immediate mixing is made, neglecting the spatial variability of chemical species within a grid cell. The first results are based on the gaseous phase only. Cloudy development in the convective boundary layer only affects the vertical transport of chemical species. The simulations show that thermals are preferential reaction zones where the chemical reactivity is the highest. The top of the boundary layer is the region characterized by the highest calculated segregation intensities but of the opposite sign in both environments. In the biogenic environment, the inhomogeneous mixing of isoprene and OH in this zone leads to a maximum decrease of 30% of the mean reaction rate. In the anthropogenic case, the effective rate constant for OH reacting with aldehydes is 16% higher at maximum than the averaged value. The OH reactivity is higher by 15 to 40% inside thermals compared to the surroundings depending on the chemical environment and time of the day. Because thermals occupy a small fraction of the simulated domain, the impact of turbulent motions on the domain-averaged OH total reactivity reaches a maximum 9% decrease for the biogenic case and a maximum of 5% increase for the anthropogenic case. LES simulations including the aqueous reactivity reveal a significant decrease in OH mixing ratios associated to the presence of clouds. Consequently, isoprene and C>2 aldehydes mixing ratios increase at these altitudes
Arnault, Nicolas Vincent. "Ondes internes de gravité pendant la transition nocturne - diurne de la couche limite atmosphérique : observations et expériences de laboratoire." Paris 6, 2005. http://www.theses.fr/2005PA066179.
Largeron, Yann. "Dynamique de la Couche Limite Atmosphérique stable en relief complexe. Application aux épisodes de pollution particulaire des vallées alpines." Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00606115.
Rio, Catherine. "Paramétrisation de la couche limite atmosphérique convective et représentation du cycle diurne des nuages dans un modèle de climat." Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00003728.
Espana, Guillaume. "Étude expérimentale du sillage lointain des éoliennes à axe horizontal au moyen d'une modélisation simplifiée en couche limite atmosphérique." Phd thesis, Université d'Orléans, 2009. http://tel.archives-ouvertes.fr/tel-00496915.
Quimbayo-Duarte, Julian. "Modélisation numérique de la couche limite atmosphérique par condition stable en terrain complexe. Application à la qualité de l'air." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU005/document.
During wintertime anticyclonic regimes, urbanized mountain areas often experience stable and decoupled atmospheric conditions, resulting in severe episodes of particulate air pollution. This study deals with the characterization of drivers of particulate air pollution in deep alpine valleys under such stable conditions from the point of view of atmospheric dynamics. The work has been carried out through the implementation of both idealized and real case numerical simulations using the Weather Research and Forecasting (WRF) model. Particulate air pollution has been modelled by implementing passive tracers in the simulations.In a first part, high-resolution numerical simulations have been performed using two different configurations of three-dimensional idealized valleys opening onto a plain. The first configuration corresponds to a valley of constant width in the along-valley direction, directly opening onto a plain. The second one consists in a valley of varying width in that direction, with an upstream section of larger width than the downstream section, which opens onto the plain. The latter configuration is referred to as a pooling case. The change in the vertical temperature profile along the valley axis in all configurations results in a horizontal pressure gradient that leads to the development of an along-valley flow. Configurations in which the upstream section of the valley opens onto a narrower one have shown to be prone to higher pollutant concentrations than in the case of a valley opening directly onto a plain, due to the weaker down-valley flow developing in the variable width configurations. The impact of the downstream valley section on the concentration of pollutants in the upstream valley section is remarkable: the ventilation of the upstream valley section can be completely blocked for most of the simulation (six hours) when the ratio of the upstream to downstream valley section width is equal to 10.The second part deals with a real case situation, focusing on a section of the alpine Arve River valley around the city of Passy. The numerical modelling of the atmospheric dynamics and particulate matter (PM) concentration in that section has been performed during a strongly polluted wintertime episode of February 2015. For this purpose the emission inventory prepared by the air quality agency of the région Auvergne Rhône-Alpes has been implemented in the WRF-Chem model. The boundary layer dynamics has been compared to wind and temperature profiles collected during a field campaign conducted during the episode, and PM concentration has been compared to data recorded by air quality stations. The contribution of the valley tributaries to air pollution within the section considered has been first studied. Results show that this contribution is very small compared to that from local sources; this implies that $in-situ$ emissions are primarily responsible for the high PM concentration recorded in the valley since the valley bottom is decoupled from the atmosphere above the valley. The ventilation characteristics of the valley and their influence on the particulate matter (PM) concentration have next been investigated. The analysis indicates that due to the limited ventilation around the city of Passy, the hourly variability of PM concentration therein is driven by that of the emissions
Samaali, Mehrez. "Evaluation d'un modèle de couche limite atmosphérique 3D dans un cas homogène : application à une parcelle agricole de soja." Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX11065.
Espana, Guillaume. "Etude expérimentale du sillage lointain des éoliennes à axe horizontal au moyen d'une modélisation simplifiée en couche limite atmosphérique." Thesis, Orléans, 2009. http://www.theses.fr/2009ORLE2066/document.
The aim of this work was to study the far wake of horizontal axis wind turbines in wind tunnels. Aerodynamic phenomena within the wakes are very complex and, most of the time, they are studied from a steady point of view : the main parameters (wake deficit, production of turbulence...) are therefore time averaged. Nevertheless, studying the wake unsteadiness of a wind turbine located in the atmospheric boundary layer (ABL) enables the consideration of the meandering phenomenon, which describes random oscillations of the wake. The present work was constructed in two main parts : firstly the steady vision and secondly the unsteady vision of a wind turbine wake, modelled according to the actuator disk theory and placed in an ABL reproduced in a wind tunnel at a geometric scale of 1/400. Several parametric studies are presented in the first part : on the influence of the wind turbine’s operating point, of its mast height and also on the influence of the ABL characteristics. Wind turbines in yaw are also considered. The wake behaviour is then studied in different configurations and the limits of the empirical laws in the literature are highlighted, especially the lack of the ambiant turbulence intensity consideration. The second part focuses on the unsteady point of view, rarely considered until today. Using hot wire anemometry, the role of the atmospheric large turbulent scales on the meandering phenomenon is proven. The oscillation magnitude and the instantaneous wake dimensions are also investigated using PIV, which leads to quantitative results on the meandering characteristics
Yahaya, Saleye. "Dynamique de la couche limite de surface semi-aride : approche des caractéristiques turbulentes par anemometrie a coupelles et effets des traitements de surface du sol." Paris 7, 2004. http://www.theses.fr/2004PA077181.
Deremble, Bruno. "Dynamique atmosphérique basse fréquence : influence d'un front de température océanique." Paris 6, 2010. http://www.theses.fr/2010PA066277.
In a first part, we focus on the origin of the atmospheric low-frequency variability. We investigated the problem of defining unambiguously weather regimes. Indeed, while we might have a pretty good idea of the physical states associated with a particular weather regime, the edge of such a regime - and hence the transitions from one regime to another - is very poorly defined. In a quasi-geostrophic (QG), barotropic, highly truncated atmospheric model, we find that the stable manifolds associated with a saddle point are good candidates to be the boundaries between the regimes. In fact, our model is designed to reproduce the topographic instability that contributes to atmospheric LFV. In our model, we find a clear correspondence between the fixed points and the weather regimes. In a second part, we focus on the ocean-atmosphere interaction and its consequences on the atmospheric low-frequency variability. Recent high-resolution observations provide new insights into extratropical ocean atmosphere interactions. Particular attention has been devoted to measure the response of the atmosphere to zones of strong sea surface temperature (SST) grandients. Indeed, the marine atmospheric boundary layer above the ocean's mid-latitude currents (e. G. , the Gulf Stream) is largely influenced by the sharp SST fronts associated with them: these gradients produce significant changes of temperature and humidity fluxes in the lower layers of the atmosphere. In my thesis, I focus on the connection between the strong SST gradients and the atmospheric dynamics and more precisely on atmospheric low-frequency variability. In a first step, we quantify the modifications in the atmospheric dynamics due to the presence of the SST front (position and amplitude of the atmospheric jet; intensity of the storm track intensity). Then, using a simple parametrization of the boundary layer, we decribe the atmospheric dynamics using the equilibrium states of a barotropic coupled model. We use the limit cycle identified in this model to explain the basin-scale atmospheric low-frequency variability
Song, Tae-Joon. "Simulation des hydrocarbures non méthaniques légers dans la couche limite atmosphérique marine pendant les expériences Lagrangiennes d'ACE 1 et d'ASTEX/MAGE." Paris 7, 2001. http://www.theses.fr/2001PA077147.
Benard, Pierre. "Etude numérique à forte résolution des bandes précipantes associées à un système frontal dans une onde barocline forcée par cisaillement." Toulouse 3, 1989. http://www.theses.fr/1989TOU30209.
Aouizerats, Benjamin. "Impacts radiatifs des aérosols sur la dynamique en couche limite urbaine : application à la campagne CAPITOUL." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1591/.
Nowaday, aerosol modelling is an absolute interest for the understanding of the complex atmospheric system. The role of aerosol particles is considered crucial for air quality, meteorological and climatical purpose. Several studies show that the aerosol physical and chemical behaviours affect the atmospheric radiative budget by scaterring and aborbing the radiative fluxes. Moreover, it has also been shown that the physical and chemical description of the aerosol is necessary to give shape to water droplets. Finally, several reports from the World Health Organisation show that the fine aerosol particles can cause major diseases as cancer or pulmonary diseases, and should be now considered as a public health matter. This study takes place in this context, and aims at estimating the radiative feedbacks of urban aerosol on the boundary layer. The CAPITOUL field experiment, which took place in the city of Toulouse during one year from march 2004 to february 2005, is the framework of a modelling study during a 2-day IOP. First, an emission inventory has been set up to reproduce the gaz and particles emissions. Then, a simulation exercise aims at reproduce the aerosol evolution at the fine scale of 500 m, and the very specific spatial distribution at different resolutions. In order to estimate the impact of aerosol particles on radiation, a radiative module has been developped to compute online the aerosol optical properties depending on the complex aerosol physical and chemical parameters. The radiative fluxes are then impacted by the aerosol scaterring and aborbing behaviour, leading to change in the urban dynamics. Those feedbacks on radiative fluxes lead to a change of the boundary layer's temperature. The impacts are also compared to the urban surface impacts
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.
Vignon, Etienne. "La couche limite extrême du Plateau Antarctique et sa représentation dans les modèles de climat." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU023/document.
Observation of the Atmospheric Boundary Layers (ABL) above the Antarctic Plateau has revealed the strongest near-surface temperature stratifications on the Earth. A correct parametrization of the very stratified Antarctic ABLs in General Circulation Models (GCM) is critical since they exert a strongcontrol on the continental scale temperature inversion, on the coastal katabatic winds and subsequently on the Southern Hemisphere circulation. The previous Gewex Atmospheric Boundary Layer Studies (GABLS) highlighted that the parametrization of the very stratified, or very stable, ABLs isone of the most critical challenge in the atmospheric modelers community. Indeed, the nature of the mixing processes are not completely understood and the commonly used similarity laws, on which the model’s parametrization are usually based, are no longer valid. The aim of this PhD work is to evaluate and improve the modelling of the ABL over the Antarctic Plateau by the Laboratoire de Météorologie Dynamique-Zoom (LMDZ) GCM, the atmospheric component of the IPSL Earth System Model in preparation for the sixth Coupled Models Intercomparison Project. Before the model evaluation itself, an in-depth study of the dynamics of the atmospheric surface layer and of the stable ABL over the Antarctic Plateau was carried out from in situ measurements at Dome C. The analysis enabled the first estimations of the roughness length and of the surface fluxes during the polar night at this location as well as the characterization of very frequent occurences of near-surface moisture supersaturations with respect to ice. Investigation of meteorological measure-ments along a 45 m tower also revealed two distinct dynamical regimes of the stable ABL at this location. In particular, the relation between the near surface inversion amplitude and the wind speed takes a typical ’reversed S-shape’, suggesting a system obeing with an hysteresis. A further analysisshowed that this is a clear illustration of a general and robust feature of the stable ABL systems, corresponding to a ‘critical transition’ between a steady turbulent and a steady ‘radiative’ regime. LMDZ was then run on 1D simulations during a typical clear-sky summertime diurnal cycle in the framework of the fourth GABLS case. Sensitivity tests to surface parameters, vertical grid and turbulent mixing parametrizations were performed leading to significant improvements of the model and to a new configuration better adapted for Antarctic conditions. 3D simulations were then carried outwith the ’zooming capability’ of the horizontal grid and with nudging. These simulations enabled a further evaluation of the model over a full year and extending the analysis beyond Dome C. In particular, this study raised the importance of the radiative scheme and of the surface layer scheme forthe modelling of the ABL during the polar night over the Plateau. Finally, the PhD work extented toward the modelling of the stable ABL over the other continents, assessing how the frequently underestimated subgrid mixing of momentum and heat can be compensated by a transfer of large scalekinetic energy toward turbulent kinetic energy when the flow is slowed down by orographic gravity wave drag
Tomas, Séverine. "Modélisation et étude expérimentale de la turbulence au sein des couches limites atmosphèriques." Toulouse 3, 2007. http://www.theses.fr/2007TOU30024.
Chevalier, Amandine. "Développement du service d'observation PAES : pollution atmosphérique à l'échelle synoptique, bilan de l'ozone dans la troposphère libre." Phd thesis, Université Paul Sabatier - Toulouse III, 2007. http://tel.archives-ouvertes.fr/tel-00193744.
Bari, Driss. "Etude du brouillard en zone côtière par modélisation des processus physiques de la couche limite atmosphérique : cas du Grand Casablanca (Maroc)." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30316/document.
The prediction of fog remains a challenge due to its time and space variability and to the complex interaction between the numerous physical processes influencing its life cycle. During the first stage of this thesis, the local meteorological and synoptic characteristics of fog occurrence over the Grand Casablanca region (Morocco) are investigated. To achieve this, hourly surface meteorological observations, at two synoptic stations of this coastal region, are used. An objective fog-type classification has been developed in this work and used to discriminate the fog events into the well known types. This fog climatology points out that the fog is often localized and that it is predominantly of advection-radiation type, followed by fog resulting from cloud base lowering and radiation fog. Besides, two different fog types can occur when fog simultaneously concerns the two stations. The advective processes associated with sea breeze circulation during the daylight, followed by the radiative processes often leads to fog formation over this coastal region. Numerical simulations are performed later using the meso-scale non-hydrostatic model Meso-NH. These simulations confirm that the physical processes, governing the life cycle of fog, can be different according to the physiographic features of the area. Moreover, the numerical prediction of coastal fog over heterogeneous area is very sensitive to sea surface temperature, land local topography and land cover. It also depends on the model's ability to reproduce the sea breeze circulation during the daylight followed by the radiative processes early in the night. The systematic numerical simulations of the fog events that occurred during the winter 2013-2014 indicate the Meso-NH's ability to well capture the fog occurrence with a relatively high false alarm rate, particularly over the coastal station
Sadek, Radi. "Modélisation de l'écoulement atmosphérique à l'échelle hectométrique." Thesis, Ecully, Ecole centrale de Lyon, 2013. http://www.theses.fr/2013ECDL0011/document.
Many practical and industrial applications, such as the study of atmospheric dispersion of pollutants, air quality,micro-meteorology in complex terrain and wind assessment, require accurate prediction of the atmospheric flow at a so-called local scale (approximately 10 km horizontally). Therefore, the main objective in this thesis is to propose a chain of methodologies capable of simulating the atmospheric flow at this scale, with a horizontal hectometric spatial resolution. First of all, we were interested in modeling of turbulence in the atmospheric boundary layer (ABL). In addition to the largely used RANS k−ε model, we considered the use of the RANS Ri j− ε model as a way of simulating turbulence anisotropy.We were able to verify the necessity of using the Duynkerke (1988) constants in order to achieve atmospheric levels of turbulence with the k− ε model. In a similar way, we also developed a new set of atmospheric constants for the Ri j− ε model. Finally, we proposed a theoretical model capable of reproducing the main characteristics of a turbulent flow for any given sampling duration, thus allowing a more continuous approach between « standard » and « atmospheric » constants for turbulence models. Also, in this thesis, we developed the « CFD 1D-3D » modeling approach. It is based on the use of a 1D CFD model as a way of providing vertical profiles of meteorological data for boundary conditions of a 3D CFD code, used in complex terrain. This 1D model was developed as a part of the thesis, along with k− ε and Ri j − ε turbulence models. It was validated by being compared with empirical and theoretical results. The comparisons showed very encouraging results concerning the ability of this model in simulating ABL in the presence of a flat terrain. In addition, the « CFD 1D- 3D » methodology was assessed by comparison with wind tunnel measurements in the presence of complex terrain, which showed very satisfactory resultst. These comparisons also validated the newly developed set of constants for the Ri j− ε model. Finally, we studied the use of partially converged CFD as a way of reducing the CPU time of CFD simulations for operational purposes. We therefore demonstrated that we can achieve a low error solution (< 10% error compared with the converged solution), with a CPU time of about 5%−10% of the time required to achieve convergence. This result was very interesting because the methodology significantly reduces the computational time while maintaining a low error as compared to the overall uncertainty of the CFD approach
Angot, Hélène. "Cycle atmosphérique du mercure dans des zones reculées de l’Hémisphère Sud : cas de la couche limite marine subantarctique et du continent Antarctique." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU014/document.
Mercury (Hg) is a metal emitted by both natural and anthropogenic sources. It is of global concern owing to its long-range atmospheric transport, its persistence in the environment, its ability to bioaccumulate in ecosystems, and its negative effects on human health. Large uncertainties associated with atmospheric models – that trace the link from emissions to deposition of Hg onto environmental surfaces – arise as a result of our incomplete understanding of atmospheric processes (oxidation pathways, deposition, and re-emission) and of the scarcity of monitoring data at a global scale. The aim of this PhD work is to improve our understanding of the atmospheric Hg cycling at three remote sites of the Southern Hemisphere: Amsterdam Island (AMS) in the Indian Ocean, Concordia (DC) on the East Antarctic ice sheet, and Dumont d’Urville (DDU) on the East Antarctic coast. Data acquired at AMS suggest a limited atmospheric reactivity of Hg in this part of the globe. The advection of polluted continental air masses being scarce, AMS is a key site for the long-term monitoring of the atmospheric background in the Southern Hemisphere mid-latitudes. Data acquired in Antarctica highlight the occurrence of unprecedented processes in the atmosphere and at the air-snow interface. Due to katabatic winds flowing out from the East Antarctic ice sheet down the steep vertical drops along the coast, processes observed at DC influence the cycle of atmospheric Hg on a continental scale. These scientific breakthroughs will ultimately lead to improved global transport and deposition models