Rôle de la vapeur d'eau atmosphérique dans la régulation du système climatique: étude des zones tropicales

L’eau, qu’elle soit vapeur, liquide ou glacée, est l’élément principal qui caractérise notre système climatique : c’est, entre autres, la cohabitation de ces 3 phases de l’eau sur Terre qui fait de celle-ci une planète si particulière. En pratique, le stock d’eau dans l’atmosphère représente moins de 0,01% de l’eau totale sur Terre, mais cette très faible quantité est essentielle dans la redistribution de l’énergie à travers le système et dans le cycle de l’eau en général : depuis l’évaporation de l’eau liquide de surface jusqu’à son retour sous forme de précipitations en passant par une variété de processus nuageux complexes. Les mouvements de la vapeur d’eau à travers le cycle de l’eau sont ainsi intimement couplés aux précipitations et à l’humidité des sols, ce qui se traduit par des climats extrêmement diversifiés sur Terre.La présence de vapeur d’eau module très fortement la distribution de l’énergie au sein du système climatique du fait de propriétés radiatives exceptionnelles, qui s’étendent depuis l’infrarouge jusqu’au microondes, et de contraintes thermodynamiques fortes, à travers des lois énergétiques parfaitement établies. Ces deux aspects donnent à la vapeur d’eau une place particulièrement importante dans le système climatique et dans sa sensibilité aux forçages.Les observations par satellite, réalisées dans des canaux dits « vapeur d’eau » permettent de documenter structures atmosphériques caractérisant les déplacements de l’air, clair ou nuageux. Elles constituent ainsi un outil idéal pour la documentation de l’eau atmosphérique et ainsi mieux comprendre les processus dynamiques et thermodynamiques qui affectent sa distribution et sa variabilité.Mes activités de recherche, depuis ma thèse soutenue en 2004, sont centrées sur la compréhension des processus qui influencent la distribution de la vapeur d’eau de la troposphère tropicale. Trois axes sont privilégiés : (i) développer des méthodes d’estimation de la vapeur d’eau troposphérique pour des radiomètres à bord de satellites, avec une attention particulière apportée aux bilans d‘incertitudes et d’erreur; et (ii) analyser la variabilité spatiale et temporelle de la vapeur d’eau et étudier les processus associés à différentes échelles spatiales et temporelles qu’ils soient ou non associés au cycle de la convection. Je détaillerai les méthodes et principaux résultats obtenus selon ces axes ainsi que les orientations que j’envisage pour mes futures activités de recherche, vues comme une continuité évidente des travaux déjà réalisés

Atas do IX Seminário Latino-americano e V Seminário Ibero-americano de Geografia Física

Atas do "IX Seminário Latino-americano e V Seminário Ibero-americano de Geografia Física

Debate and Game: The Relevant Britain Literary Award – Enabling students to discuss contemporary issues in a safe and engaging way

Proposal: Ever wondered what it would like to be a judge on a literary award? Come play the Relevant Britain literary award game – a workshop or seminar activity designed to overcome resistance, enable debate and enliven discussion over difficult current topics in a safe environment. Be a judge on a fictional literary award and perform your character to the fullest in order to influence the discussion, evidence your point and carry across your objective of awarding or not a current title the Relevant Britain award. Take part in this workshop activity and learn how to carry it through on your own. Description: In a recent Contemporary Writing module, we encountered unexpected resistance from third-year undergraduate students around issues in the literary zeitgeist such as politics, race, feminism and others. This third-year module aims to investigate what is happening in contemporary writing and pays attention to best-selling and award winning books and artefacts (such as interactive stories and podcasts) to highlight the current situation of publishing and literature. As an English module, engagement and debate in lectures, tutorials and seminars are highly relevant for generating a good student experience and enabling learning. To overcome student resistance, to challenge all students to safely discuss difficult topics and to achieve a good level of engagement, we created the Relevant Britain game. This activity asks students to participate as fictional judges of a literary award. Each student is given a character with a few notes on their personality, their politics and their initial ideas about the book they are judging for the award. In character, students debate the reasons why the week’s book should or should not be given the Relevant Britain award. This activity enables them to engage with arguments other than their own, to make theirs more robust and evidenced when facing opposition, and to present relevant arguments in order to sway the opinion of others. It also allowed them to debate themes related to the module such as the role of technology in contemporary literature, the place of literary awards in a writer’s career and what factors might influence award judges when deciding. For this workshop, we want to run a Relevant Britain game and allow participants to experiment for themselves how games can help lower resistance and enliven seminars and tutorials by helping lead safe, engaged discussions on important topics. We will provide a guide on how to run the Relevant Britain game and host a discussion on the role of games in overcoming resistance. Materials will be provided. Keywords: Teaching, Workshop, Debate, Seminar Activities, Games, Contemporary Literature, Creative Writing, English, Social Issues, Cultural Issue

Island Biogeography in the Anthropocene and Quaternary

The realization that human activities have a major influence on ecosystems from local to global scales has given rise to the concept of the Anthropocene. However, although the influence of human activities on biodiversity is clearly significant, it remains unclear to what extent the rate and magnitude of biodiversity changes differ from pre-human dynamics. Islands are ideal model systems for understanding the relative contribution of environmental and societal variables to biodiversity change because the onset of human activities on islands can generally be clearly defined. The aim of this PhD thesis is to place human-environment interactions on islands in the context of environmental fluctuations over the Quaternary. The thesis consists of two parts. First, I quantify how island area and isolation have changed over the Quaternary as a result of climate-driven sea-level fluctuations, and analyse how these dynamics have shaped modern biodiversity patterns. Secondly, I study how human activities in the past and present have shaped island ecosystems and landscapes, and compare their rate and magnitude to pre-human dynamics. Overall, the findings of my thesis indicate that modern biodiversity patterns show legacies of past human activities but are also imprinted by environmental dynamics in deep-time. Furthermore, the rate of change following human settlement on islands can largely exceed Quaternary background rates. Therefore, my findings are in line with studies that indicate that human activities have become a major driver in shaping biodiversity across scales. Nonetheless, my comparison of islands worldwide also highlights the diverse ways in which abiotic, biotic, and anthropogenic variables have interacted across individual islands. Therefore, future studies should acknowledge that global biodiversity change can manifest differently across localities. Finally, I emphasize the importance of strengthening interdisciplinary approaches in island biogeography to enhance our understanding of biodiversity changes in the Anthropocene, and how they relate to deeptime dynamics.A constatação de que as atividades humanas exercem uma grande influência sobre os ecossistemas, da escala local à global, originou o conceito do Antropoceno. No entanto, apesar da influência das atividades humanas ser claramente significativa, ainda não está claro até que ponto a taxa e magnitude de alterações na biodiversidade diferem da dinâmica pré-humana. As ilhas constituem sistemas modelo ideais para compreender a contribuição relativa de variáveis ambientais e sociais, porque o início das atividades humanas é em geral conhecido. O objetivo desta tese de doutoramento é enquadrar as interações homem-ambiente nas ilhas no contexto das flutuações ambientais no Quaternário. A tese consiste em duas partes. Primeiro, quantifico como a área da ilha e o isolamento mudaram no Quaternário devido às flutuações do nível do mar provocadas pelo clima e analiso como essas dinâmicas moldaram os padrões modernos de biodiversidade. Em segundo lugar, estudo como as atividades humanas passadas e presentes moldaram os ecossistemas e paisagens das ilhas e comparo a sua taxa e magnitude com a dinâmica pré-humana. As conclusões de minha tese indicam que os padrões modernos de biodiversidade mostram legados de atividades humanas passadas, mas também são afectados pela dinâmica ambiental em escalas temporais longinquas. Além disso, a taxa de alterações após o povoamento humano nas ilhas pode exceder largamente taxas quaternárias antecedentes. Os meus resultados concordam com estudos mostrando que as atividades humanas têm sido um fator importante na modelação da biodiversidade ao longo do tempo. Mas a minha comparação global de ilhas também destaca diversas maneiras pelas quais variáveis abióticas, bióticas e antropogénicas interagiram entre ilhas. Estudos futuros devem reconhecer que a mudança global da biodiversidade pode manifestarse de formas diferente entre localidades. Por fim, destaco a importância de aumentar abordagens interdisciplinares na biogeografia insular para melhor compreender as mudanças da biodiversidade no Antropoceno

SBE16 Brazil & Portugal - Sustainable Urban Communities towards a Nearly Zero Impact Built Environment

Vol. IThe organizers of SBE 16 Brazil & Portugal were challenged to promote discussions and the development of solutions for an important and, at the same time, very ambitious topic ? Sustainable Urban Communities towards a Nearly Zero Impact Built Environment. This is the main focus of the international conference SBE16 Brazil & Portugal; the only event of the SBE16/17 conference series being held in Latin America, more precisely, in Vitória (Espírito Santo), Brazil, from the 7th until the 9th of September 2016. The conference offered a unique opportunity to bring together researchers from all over the world to share evidence-based knowledge in the field and succeeded to achieve its goals since many contributions from various parts of the planet were received, addressing a tiny part of the problem or trying to perform the difficult task of making the sum of the parts a coherent whole.info:eu-repo/semantics/publishedVersio

SBE16 Brazil & Portugal - Sustainable Urban Communities towards a Nearly Zero Impact Built Environment

Vol. IThe organizers of SBE 16 Brazil & Portugal were challenged to promote discussions and the development of solutions for an important and, at the same time, very ambitious topic ? Sustainable Urban Communities towards a Nearly Zero Impact Built Environment. This is the main focus of the international conference SBE16 Brazil & Portugal; the only event of the SBE16/17 conference series being held in Latin America, more precisely, in Vitória (Espírito Santo), Brazil, from the 7th until the 9th of September 2016. The conference offered a unique opportunity to bring together researchers from all over the world to share evidence-based knowledge in the field and succeeded to achieve its goals since many contributions from various parts of the planet were received, addressing a tiny part of the problem or trying to perform the difficult task of making the sum of the parts a coherent whole.info:eu-repo/semantics/publishedVersio

Modelagem dos processos físico-químicos e atmosféricos envolvidos na formação de oxidantes fotoquímicos em megacidades: o caso da região metropolitana do Rio de Janeiro

Presents an integrated computational system composed of a meteorological model, biogenic / anthropogenic emissions and air quality, implemented and adequate in a high performance computational platform, for the understanding of dynamic, thermodynamic and physico-chemical processes that impact on the formation of Photochemical oxidants in RMRJ. For better representativeness of the results, methodologies were developed that provided atmospheric emissions databases in high resolution. Statistical assessments of system performance were performed comparing with observed data from meteorological stations and the air quality monitoring network, and an investigation of atmospheric pollutant concentrations occurred in different meteorological conditions. The results are presented in digital maps on the geographic information system platform for an integrated environmental analysis.Apresenta um sistema computacional integrado composto por modelo meteorológico, de emissões biogênicas/antropogênicas e da qualidade do ar, implementado e adequado em plataforma computacional de alto desempenho, para o entendimento dos processos dinâmicos, termodinâmicos e físico-químicos que impactam na formação de oxidantes fotoquímicos na RMRJ. Para uma melhor representatividade dos resultados foram desenvolvidas metodologias que forneceram bases de dados de emissões atmosféricas em alta resolução. Avaliações estatísticas de desempenho do sistema foram realizadas comparando com dados observados de estações meteorológicas e da rede de monitoramento da qualidade do ar, e uma investigação das concentrações de poluentes atmosféricos se deu em diferentes condições meteorológicas. Os resultados são apresentados em mapas digitais na plataforma de sistema de informações geográficas para uma análise ambiental integrada

The Matching-Graph

The increasing amount of data available and the rate at which it is being collected is driving the rapid development of intelligent information processing and pattern recognition systems. Often the underlying data is inherently complex, making it difficult to represent it using linear, vectorial data structures. Graphs offer a versatile alternative for formal data representation. Actually, quite a number of graph-based pattern recognition methods have been proposed, and a considerable part of these methods rely on graph matching. This thesis introduces a novel method for encoding specific graph matching information into a meta-graph, termed matching-graph. The basic idea is to formalize the stable cores of individual classes of graphs – discovered during intra-class matching. This meta-graph is useful in several applications ranging from the analysis of inherent patterns, over graph classification, to graph augmentation. The benefits of the matching-graphs are evaluated in three parts. First, their usefulness in classification scenarios is evaluated in two approaches. The first approach is a distance-based classifier that focuses on the matching-graphs during dissimilarity computation. The second approach uses sets of matching-graphs to embed input graphs into a vector space. The basic idea is to first generate hundreds of matching-graphs, and then represent each graph g as a vector that shows the occurrence of, or the distance to, each matching-graph. In a thorough experimental evaluation on real-world data sets it is empirically confirmed that these novel approaches are able to improve the classification accuracy of systems that rely on comparable information as well as state-of-the-art methods. The second part of the research targets a prevalent challenge in graph-based pattern recognition, viz. computing the maximum common subgraph (MCS). Current exact algorithms compute the MCS with exponential time complexity. In this second part, it is investigated whether matching-graphs, computable in polynomial time, provide a suitable approximation for the MCS. Results show that, for specific graphs, a matching-graph equals the maximum common edge subgraph, thereby establishing an upper limit to the size of the maximum common induced subgraph. The experimental evaluation further confirms that matching-graphs outperform existing algorithms in terms of computation time and classification accuracy. The third part of this thesis addresses the problem of graph augmentation. Regardless of the actual representation formalism used, it is inevitable that supervised pattern recognition algorithms need access to large sets of labeled training samples. However, in some cases, this requirement cannot be met because the set of labeled samples is inherently limited. The last part shows that matching-graphs can be used to augment graph training sets in order to make the training of a classifier more robust. The benefit of this approach is empirically validated in two different experiments. First, the augmentation approach is studied on very small graph data sets in conjunction with a graph kernel classifier, and second, the augmentation approach is studied on data sets with reasonable size in conjunction with a graph neural network classifier

Etude par modélisation et assimilation de données d'un capteur infrarouge géostationnaire pour la qualité de l'air

L'objectif de cette thèse porte sur la définition d'un capteur géostationnaire infrarouge pour l'observation de la composition chimique de la basse troposphère et l'évaluation de la valeur ajoutée de cet instrument afin de caractériser la variabilité de la moyenne et basse troposphère des principaux polluants et d'améliorer l'observation et les prévisions de la qualité de l'air. Nous nous sommes intéressés à deux polluants importants: l'ozone troposphérique en raison de son impact sur la santé humaine, les écosystèmes et le climat, et le monoxyde de carbone (CO) qui est un traceur de pollution nous renseignant sur les sources d'émissions et les processus de transport. Dans un premier temps, une évaluation d'un schéma linéaire pour la chimie du CO a été effectuée sur une période d'un an et demi en comparaison avec un schéma chimique détaillé (RACMOBUS) et différents types d'observations troposphériques et stratosphériques (satellitaires, aéroportées). L'intérêt principal de ce schéma est son faible coût en temps de calcul qui permet une assimilation sur de longues périodes de jeux de données de CO. L'assimilation de données MOPITT (Measurements Of Pollution In The Troposphere) dans ce schéma a d'ailleurs permis d'évaluer la valeur ajoutée de données d'observations infrarouges à l'échelle globale. Ensuite, les caractéristiques optimales du capteur géostationnaire infrarouge ont été définies en réalisant des études d'inversion de spectres atmosphériques pour sonder l'ozone et le CO pour la qualité de l'air, le but étant d'avoir un capteur techniquement et économiquement faisable, capable de sonder la basse troposphère. Le contenu en information de cet instrument a été comparé, en période estivale, à l'information apportée par un autre instrument infrarouge géostationnaire similaire à MTG-IRS (Meteosat Third Generation - Infrared Sounder), optimisé pour la mesure de la vapeur d'eau et de la température mais capable d'avoir une information sur la composition chimique de l'atmosphère. Enfin dans une dernière partie, la valeur ajoutée de ces deux instruments dans le modèle de qualité de l'air MOCAGE, a été quantifiée en utilisant des expériences de simulation de système d'observations sur une période de deux mois d'été (juillet - août 2009). La capacité de ces deux instruments à corriger différentes sources d'erreurs (les forçages atmosphériques, les émissions, l'état initial et les trois paramètres réunis) qui affectent les prévisions et simulations de qualité de l'air, a été quantifiées. Au final, l'instrument que nous avons défini s'avère effectivement capable d'apporter une contrainte efficace sur les champs d'ozone et de CO dans la moyenne et basse troposphère.The objective of this thesis is to define a geostationary infrared sensor to observe the atmospheric composition of the lowermost troposphere. We evaluate the potential added value of such an instrument at characterizing the variability of the main pollutants and improving air quality observations and forecasts. We focus on two air quality key pollutants: tropospheric ozone, because of its impact on human health, ecosystems and climate; carbon monoxide (CO), which is a tracer of pollutants emissions. Firstly, an evaluation of a linear scheme for the CO chemistry during one year and a half has been performed in comparison with a detailed chemical scheme (RACMOBUS) and different tropospheric and stratospheric observations (satellite and aircraft data). The advantage of such a scheme is its low computational cost which allows data assimilation of CO during long periods. Assimilation of CO data from the Measurements Of Pollution In The Troposphere (MOPITT) instrument allows us to evaluate the information brought by such infrared observations at the global scale. Secondly, the optimal configuration of a new infrared geostationary sensor has been defined using retrieval studies of atmospheric spectra with the objectives to contribute to the monitoring of ozone and CO for air quality purposes; our constraint also set the ground for a sensor with technically feasible and affordable characteristics. For reference, the information content of this instrument has been compared during summer to the information content from another infrared geostationary instrument similar to MTG-IRS (Meteosat Third Generation - Infrared Sounder), optimized to monitor water vapour and temperature but with monitoring atmospheric composition as Lastly, the potential added value of both instruments for air quality prognoses has been compared using observing system simulation experiments (OSSEs) over two summer months (July - August 2009). The skill of the two instruments to correct different error sources (atmospheric forcing, emission, initial state and the three conditions together) affecting air quality simulations and forecasts, has been characterised. In the end, it is concluded that the instrument configuration proposed is effectively able to bring a constraint on ozone and CO fields in the mid-to-low troposphere