Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this Dissertation were identified events of influence of the Antarctic ozone hole over the South of Brazil that occurred in the period between 1979 and 2011. For this, we analyzed the daily average data of total ozone column obtained through the Brewer Spectrophotometers MKIV #081 model during the period 1992-2000, MKII model #056 of 2000-2002 and MKIII #167 model from 2002 to the present day, installed in the Southern Space Observatory- OES/CRS/INPE MCTI (29,4 °S; 53,8°O; 488,7m) and by satellite instruments Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) to the same latitude of the southern Space Observatory in the absence of surface equipment data, searching for days of falls in ozone content. For these days, isentrópicas analyses were conducted of potential vorticity using Reanalysis data provided by the National Centers for Environmental PredictionAtmospheric Research (NCEPNCAR), in order to verify the origin of ozone-poor air mass. Confirmation of the origin of polar air masses took place through the analysis of the trajectories retroactive made through the Hysplit model of NOAA. In addition, it was also conducted a complementary analysis through the pictures of the ozone content of TOMS and OMI, the ozone hole in the Antarctic region and its connection to the South of Brazil. The methodology used was effective in the identification of 66 events of the Influence of Antarctic Ozone Hole over south of Brazil, which showed an average drop of 8.66 ± 3.13 in the ozone content. The identification of the stratospheric circulation pattern through the medium of the vorticity field potential for the occurrence of the phenomenon was performed. In addition, were shown an analysis of synoptic weather troposphere during the occurrence of two events, noting that in both cases, the events occurred in a situation front post on the South of Brazil, coupled with the passage of the input region polar polar or subtropical jet stream, characterized by the occurrence of the event of the tropopause folding where stratospheric air intrusion occurs in the troposphere, and advancement of a high-pressure front post system that prevents the formation of significant cloud cover. Leveraging the operating environment of the Atmospheric Modeling Group (GRUMA) at the Federal University of Santa Maria (UFSM), using data from the output of numerical weather forecasting model Global Forecast System (GFS) in making maps of potential vorticity, can carry out effectively the clue of the forecast arrival of stratospheric air masses of polar origin on the southern Brazil during the spring of the year of 2012 with at least four days in advance, coinciding with the events of transport these side effects of the Antarctic ozone hole over the South of Brazil identified in the current year. / Na presente Dissertação foram identificados os eventos de Efeito Secundário do Buraco de Ozônio Antártico ocorridos sobre o Sul do Brasil no período entre 1979 e 2011. Para isso, foram analisados os dados médios diários da coluna total de ozônio obtidos através dos Espectrofotômetros Brewer modelo MKIV #081 durante o período de 1992 2000, modelo MKII #056 de 2000 2002 e modelo MKIII #167 de 2002 até os dias atuais, instalados no Observatório Espacial do Sul OES/CRS/INPE MCTI (29,4 °S; 53,8°O; 488,7m) e pelos instrumentos de satélite Total Ozone Mapping Spectrometer (TOMS) e Ozone Monitoring Instrument (OMI) para a mesma latitude do Observatório Espacial do Sul na falta de dados do equipamento de superfície, buscando dias de quedas no conteúdo de ozônio. Para estes dias, foram realizadas análises isentrópicas de vorticidade potencial utilizando dados de reanálise fornecidos pelo National Centers for Environmental Prediction/Atmospheric Research (NCEP/NCAR), a fim de verificar a origem da massa de ar pobre em ozônio. A confirmação da origem polar das massas de ar deu-se através da análise das trajetórias retroativas confeccionadas através do modelo Hysplit da NOAA. Além disso, foi também realizada uma análise complementar através das imagens do conteúdo de ozônio dos satélites TOMS e OMI, verificando-se a atuação do Buraco de Ozônio na região Antártica e sua conexão com o Sul do Brasil. A metodologia empregada mostrou-se eficaz na identificação de 66 eventos de Efeito Secundário do Buraco de Ozônio Antártico sobre o Sul do Brasil, os quais apresentaram uma queda média de 8,66 ± 3,13 % no conteúdo de ozônio. Foi realizada a identificação do padrão de circulação estratosférica através da confecção do campo médio da vorticidade potencial para os dias de ocorrência do fenômeno. Além disso, foram mostradas as analises das condições sinótica troposférica durante a ocorrência de dois eventos, observando-se que em ambos os casos, os eventos ocorreram em uma situação pós frontal sobre o Sul do Brasil, associada à passagem da região de entrada polar da corrente de jato subtropical ou polar, caracterizada pela ocorrência de evento de quebra da tropopausa onde ocorre intrusão de ar estratosférico para dentro da troposfera, e avanço de um sistema de alta pressão pós frontal que impede a formação de nebulosidade significativa. Aproveitando o ambiente operacional do Grupo de Modelagem Atmosférica (GRUMA) da Universidade Federal de Santa Maria (UFSM), utilizando dados da saída do modelo de previsão numérica de tempo Global Forecast System (GFS) na confecção de mapas de vorticidade potencial, pode-se realizar eficazmente a previsão do indício da chegada de massas de ar estratosféricas de origem polar sobre o Sul do Brasil durante o período da primavera do ano de 2012, com pelo menos quatro dias de antecedência, coincidindo estes transportes com os eventos de Efeito Secundário do Buraco de Ozônio Antártico sobre o Sul do Brasil identificados no corrente ano.

VILLELA, FRANCO N. J. Análise decadal do fluxo de CO2 entre o oceano e a atmosfera na passagem de Drake, Oceano Austral. 2011. 148 f. Dissertação (mestrado) Programa de Pós-Graduação em Ciência Ambiental (PROCAM), Universidade de São Paulo, São Paulo, 2011. Para a área delimitada pelos paralelos 60ºS e 62,5ºS e pelos meridianos 60ºW e 65ºW, localizada no sul da Passagem de Drake, no Oceano Austral, próximo à Península Antártica, foram calculadas as distribuições médias de 2000 a 2009, sazonais e anual, do fluxo de CO2 na interface oceano-atmosfera e de suas variáveis associadas: a pressão parcial de CO2 na superfície marinha (PCO2sw), a pressão parcial de CO2 na atmosfera (PCO2ar), a diferença da pressão parcial de CO2 entre o oceano e a atmosfera (PCO2) e a taxa de transferência gasosa (TR), que é produto do coeficiente solubilidade do CO2 na água do mar pela velocidade de transferência gasosa. A parametrização utilizada no cálculo dos fluxos foi a de Takahashi et al. (2009) com TR dependente da velocidade do vento ao quadrado multiplicada por um fator de escala 0,26. A área de estudo tem cerca de 75 mil km2 e foi dividida em uma grade espacial de 0,5º x 0,5º, resultando em 50 quadrículas. Foram utilizados mais de 46 mil medições de PCO2sw, que na média espacial variou de 362,7 ±11,2 a 371,9 ±17,5 µatm, no verão e primavera respectivamente. A PCO2 variou de -0,4 a 5,7 µatm no outono e primavera, respectivamente. A TR variou de 0,065 ±0,04 a 0,088 ±0,002 gC.mês-1.m-2.µatm-1, no verão e inverno, respectivamente. O fluxo líquido, se tomando a concentração de gelo como negligenciável, variou de -0,039 ±0,865 a 0,456 ±1,221 gC.m-2.mês-1, no outono e inverno, respectivamente. O fluxo total anual de carbono, estimado através da média espacial por quadrícula, foi de 95 GgC.ano-1. Dessa maneira, na estimativa anual, a superfície do mar se comporta como fonte de CO2 para a atmosfera, principalmente devido à região da plataforma continental com PCO2sw consideravelmente maior que o da atmosfera. Sazonalmente sugere-se que no verão a maior disponibilidade de radiação solar, a temperatura da superfície do mar (TSM) mais elevada e os ventos mais fracos favorecem a produção de biomassa fitoplanctônica, fazendo com que a bomba biológica seja o processo dominante na diminuição da PCO2sw e na absorção de CO2 atmosférico pela superfície marinha. Já no inverno, os ventos se intensificam e, associados com o forte resfriamento da TSM, promovem a mistura com águas profundas ricas em carbono inorgânico dissolvido, levando a superfície marinha a um estado de supersaturação de CO2 em relação à atmosfera. Ventos circumpolares de oeste mais intensos e deslocados para sul tem sido apontados como a causa do aumento da PCO2sw em igual ou maior taxa do que ocorre na atmosfera. Na área de estudo foi levantada uma tendência média da intensidade do vento de 0,23 ±0,03 m.s-1.década-1 e um aumento na freqüência da componente zonal de oeste (positiva) de 1,47 ± 1,13 % .década-1. Sugere-se que estas tendências estejam relacionadas com o Modo Anular Austral (SAM). Entretanto, a tendência decadal estimada para a PCO2sw foi menor que para a atmosfera, apesar de ambas indicarem tendência de aumento. Acredita-se que a grande variabilidade e distribuição esparsa de dados tenham mascarado a magnitude da estimativa da tendência de PCO2sw. / VILLELA, FRANCO N. J. Decadal analysis of the CO2 sea-air flux in the Drake Passage, Southern Ocean 2011. 148 f. Dissertação (mestrado) Programa de Pós-Graduação em Ciência Ambiental (PROCAM), Universidade de São Paulo, São Paulo, 2011. For the area bounded by parallels 60°S and 62.5°S and meridians 60°W and 65°W, located in the southern Drake Passage in the Southern Ocean, near the Antarctic Peninsula, mean seasonal and annual distributions of CO2 flux at the ocean-atmosphere interface, from 2000 to 2009, have been computed, as well as their associated variables: the CO2 partial pressure at sea surface (PCO2sw), the CO2 partial pressure in atmosphere (PCO2ar), the CO2 pressure difference between ocean and atmosphere (PCO2), and the gas transfer rate (TR), which is the product of the CO2 solubility coefficient in sea water by the gas transfer velocity. The parameterization used to calculate fluxes was that of Takahashi et al. (2009) with TR depending on the squared wind speed multiplied by a scale factor 0.26. The study area has about 75,000 km2 and was divided into a grid of 0.5° x 0.5°, resulting in 50 area boxes. Over 46,000 PCO2sw measurements were used, which in the spatial mean varied from 362.7±11.2 to 371.9±17.5 µatm, in summer and spring, respectively. The PCO2 varied from 0.4 to 5.7 µatm in autumn and spring, respectively. TR varied from 0.065±0.04 to 0,088±0.002 gC.month-1.m-2.µatm-1, in summer and winter, respectively. The net flux, taking ice concentration as negligible, varied from 0.039±0.865 to 0.456±1.221 gC.month-1.m-2, in autumn and winter, respectively. The total annual carbon flux, estimated through the spatial mean per square, was 95 GgC.y-1. Thus, in the annual estimate the region acts as a source to the atmosphere, mainly due to the continental shelf having PCO2sw considerably greater than that of the atmosphere. Seasonally, it is suggested that in summer the greater availability of solar radiation, warmer sea surface temperature (SST), and weaker winds favor the production of phytoplanktonic mass, making the biological pump the dominating process in lowering the PCO2sw and the absorption of atmospheric CO2 by the sea surface. On the other hand, in winter winds intensify and, in association with the strong cooling of the SST, promote mixing with deep waters rich in dissolved inorganic carbon, leading the sea surface to a state of supersaturation in CO2 relative to the atmosphere. Stronger circumpolar west winds and displaced to the south have been pointed as the cause for the increase of PCO2sw at a rate equal to or greater than that occurring in the atmosphere. In the study area it has been detected a mean trend of wind intensity 0.23±0.03 m.s-1.decade-1 and an increase in the western zonal component of 1.47±1.3%.decade-1. It is suggested that these trends are related to the Southern Annular Mode (SAM). However, the decadal trend estimated for the PCO2sw was smaller than for the atmosphere, in spite of both indicating increasing tendencies. It is believed that the great variability and scatter distribution of the data have masked the magnitude of the PCO2SW trend estimate.

Altitudinal gradients in Sub-Antarctic freshwater systems present unique opportunities to study the effect of distinct environmental gradients on benthic macroinvertebrate community composition and dispersal. This study investigates patterns in biodiversity, dispersal and population genetic structure of benthic macroinvertebrate fauna across an altitudinal gradient between two watersheds on Navarino Island in southern Chile. Patterns in diversity, density, evenness and functional feeding groups were not significantly different across the altitudinal gradient in both the Windhond and Róbalo Rivers. Taxa richness in both rivers generally increased from the headwaters of the river to the mouth, and functional feeding group patterns were consistent with the predictions of the River Continuum Concept. Population genetic structure and gene flow was investigated by sampling the mitochondrial cytochrome oxidase I gene in two invertebrate species with different dispersal strategies. Hyalella simplex (Amphipoda) is an obligate aquatic species, and Meridialaris chiloeense (Ephemeroptera) is an aquatic larvae and a terrestrial winged adult. Contrasting patterns of population genetic structure were observed. Results for Hyalella simplex indicate significant differentiation in genetic structure in the Amphipod populations between watersheds and lower genetic diversity in the Róbalo River samples, which may be a result of instream dispersal barriers. Meridialaris chiloeense exhibited weak population structure but higher genetic diversity, which suggests this species is able to disperse widely as a winged adult.

Les changements climatiques ont un impact certain sur les écosystèmes marins. Un déplacement vers le sud des principaux systèmes de front servant de sites de nourrissage pour de nombreuses espèces de prédateurs supérieurs est susceptible de se produire dans les zones subantarctiques. Les « central place foragers », tels que les pinnipèdes, sont susceptibles de faire face à une augmentation de la distance entre leurs lieux d'alimentation et leurs colonies d'élevage. Nous avons étudié l’impact des changements climatiques sur le succès d’élevage et la dynamique de population des otaries à fourrure (Arctocephalus gazella) des Îles Kerguelen par le biais du développement du modèle individu centré, MarCPFS (Marine Central Place Foragers Simulator) qui montre que la survie du couple femelle-jeune est particulièrement sensible à la répartition des proies (abondance et structure), à la capacité de mémorisation des meilleurs sites de nourrissages trouvés par la femelle pendant la période d'élevage, à la taille des femelles et à la distance qu'il faut parcourir pour trouver la ressource. Les résultats suggèrent qu’au cours des trois prochaines décennies un déplacement vers le sud supérieur à 2km an 1 pourrait compromettre la survie et la durabilité des populations. Un couplage avec un modèle de simulation de la dynamique océanique et de la ressource (SEAPODYM) a permis des projections jusqu’à la fin de ce siècle basées sur le scénarios RCP8.5 du GIEC (2014), confirmant les tendances mises à jour précédemment. Ces travaux montrent que les perspectives de maintien des populations sont pessimistes y compris en envisageant une adaptation de la taille des individus. / Climate change has certain impact on the marine ecosystems. A southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in the Subantarctic areas. Central place foragers, as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. We studied the impact of climate change on the breeding success and population dynamics of Antarctic fur seals (Arctocephalus gazella) at Kerguelen Islands by means of an individual based model we developped, MarCPFS (Marine Central Place Foragers Simulator) which showed that the survival of the female-pup pair is particularly sensitive to the distribution of preys (abundance and structure), to the memorization abilities of the best resource sites found by the female during the rearing period, to the female size and to the foraging distance which it is necessary to cover at each trip. The results suggest that during the next three decades a southward shift greater than 2 km year-1 could compromise the survival and the sustainability of the populations. A coupling with a model of simulation of the oceanic dynamics and the resource (SEAPODYM) allowed projections till the end of this century based on scenarios RCP8.5 of the IPCC (2014), confirming the trends previously obtained. Globally, these works lead us to conclude with pessimistic perspectives about the sustainability of populations even when considering an evolution through time towards individuals of greater sizes.

<p>Understanding climate-driven changes in global land-based ice volume is a critical component in our capability to predict how global sea level will rise as a consequence of the current human-driven climate change. At the last glacial maximum (LGM, which peaked around 20 ka), ephemeral ice sheets covered vast regions of the northern hemisphere while both the Greenland and Antarctic ice sheets were more extensive than at present. As global temperatures rose at the transition into the Holocene, driving the LGM deglaciation, eustatic sea level rose by approximately 125 m. The east Antarctic ice sheet (EAIS) is the largest ice sheet on Earth today, holding an ice volume equivalent to ca. 53 m rise in global sea level. Considering current trends in global climate, specifically rapidly increasing atmospheric CO₂ levels and global temperature, it is important to improve our understanding of how the EAIS will respond to global warming so that we can make better predictions of future sea level changes to guide community adaptation and planning efforts. Numerical ice sheet models which inform projections of future ice volume changes, and can, therefore, yield projections of sea level rise, rely on empirical data to test their ability to accurately represent former and present ice configurations. However, there is a general lack of data on the paleoglaciology of the EAIS along the western Dronning Maud Land (DML) margin. In order to address this situation, the paleoglaciology of western DML forms the focus of the work presented in this thesis.</p><p><b> </b></p><p>Together with collaborators within the MAGIC-DML consortium (Mapping, Measuring and Modelling Antarctic Geomorphology and Ice Change in Dronning Maud Land) that provides the funding for this MS project, the author has performed geomorphological mapping across western DML; an area of approximately 200,000 km². The results of the mapping presented in this thesis will provide the basis for a detailed glacial reconstruction of the region. The geomorphological mapping was completed almost entirely by remote sensing using very high-resolution (sub-meter in the panchromatic) WordView-2 and WorldView-3 (WV) satellite imagery, combined with ground validation studies during field work. Compared to Landsat products, the improved spatial resolution provided by WV imagery has fundamentally changed the scale and detail at which remote sensing based geomorphological mapping can be completed. The mapping presented here is focused on the glacial geomorphology of mountain summits and flanks that protrude through the ice sheet’s surface (nunataks). In our study area of western DML these nunatak surfaces make up <0.2 % of the total surface area, and the landforms mapped here are generally smaller than can be identified from Landsat products (30 m spatial resolution). The detail achieved in our mapping, across such a vast, remote area that presents numerous obstacles to accessibility highlights the benefits of utilizing the new VHR WV data. As such an evaluation of the WV data, as applied to geomorphological mapping is presented here together with our mapping of the glacial geomorphology of western DML. The results of which provides evidence of ice having overridden sites at all elevations across the entire study area; from the highest elevation inland nunataks that form the coast-parallel escarpment, to low-elevation emerging nunataks close to the coast. Hence from our studies of the glacial geomorphology of this region we can ascertain that, at some point in the glacial history of western DML, ice covered all of the mountain summits that are exposed today, indicating an ice sheet surface lowering of up to 700 m in some places.</p>

La glace de mer couvre jusqu’à 6% de la surface de notre planète. Autour du continent Antarctique, sa superficie varie entre 3.8 et 19 millions de km² (en février et septembre respectivement). Cette superficie présente des variations interannuelles. En parallèle, une évolution de la superficie de la glace de mer a également pour origine le réchauffement climatique global, très médiatisé à l’heure actuelle. Dans ce contexte, et étant donné le rôle que joue la banquise au sein de l’Océan Austral, des études de l’évolution de la glace de mer sont devenues fondamentales. <p>Ce travail a pour objectif d’étudier les relations complexes qui existent entre les processus chimiques, physiques et biologiques qui se déroulent au sein de la glace de mer. La détermination des propriétés physiques et de la composition chimique des glaces de mer correspond en effet à un pré-requis indispensable à l’étude des cycles géochimiques qui existent dans la banquise.<p>Différentes glaces de mer, naturelles ou artificielles, ont été analysées. Pour ce faire, les caractéristiques spécifiques à ce type de glace font que des méthodes d’analyse de la composition en gaz particulières ont été nécessaires.<p>Nous avons ainsi pu montrer que le contenu et la composition en gaz des différentes glaces analysées dépendent de facteurs physico-chimiques et de facteurs biologiques. L’impact des facteurs physico-chimiques se marque lors de l’incorporation initiale des impuretés dans la glace de mer et via une diffusion "post-génétique" tant que la glace est plus chaude que –5°C. En outre, les organismes photosynthétiques sont à l’origine d’une production d’oxygène et d’une consommation de dioxyde de carbone. La composition en gaz résultante peut donc être sensiblement différente de la composition atmosphérique ou de celle des gaz dissous dans l’eau de mer sous-jacente, en été comme en hiver. Il s’agit par conséquent de sérieusement envisager l’impact potentiel de la glace de mer et des microorganismes qu’elle contient, lors du réchauffement et de la débâcle, sur les échanges entre atmosphère et océan comme sur leurs compositions respectives.<p> / Doctorat en sciences, Spécialisation géographie / info:eu-repo/semantics/nonPublished

Recent progress in the modelling of the dynamics of the Antarctic ice sheet has led to a paradigm shift in the perception of the Antarctic ice sheet in a changing climate. New understanding of the dynamics of the Antarctic ice sheet now suggests that the response of the Antarctic ice sheet to climate change will be driven by instability mechanisms in marine sectors. As concerns have grown about the response of the Antarctic ice sheet in a warming climate, interest has grown simultaneously in predicting with quantified uncertainty the evolution of the Antarctic ice sheet and in clarifying the role played by uncertainties in predicting the response of the Antarctic ice sheet to climate change. Essential ice-sheet models have recently emerged as computationally efficient ice-sheet models for large-scale and long-term simulations of the ice-sheet dynamics and integration into Earth system models. Essential ice-sheet models, such as the fast Elementary Thermomechanical Ice Sheet (f.ETISh) model developed at the Université Libre de Bruxelles, achieve computational tractability by representing essential mechanisms and feedbacks of ice-sheet thermodynamics through reduced-order models and appropriate parameterisations. Given their computational tractability, essential ice-sheet models combined with methods from the field of uncertainty quantification provide opportunities for more comprehensive analyses of the impact of uncertainty in ice-sheet models and for expanding the range of uncertainty quantification methods employed in ice-sheet modelling. The main contributions of this thesis are twofold. On the one hand, we contribute a new assessment and new understanding of the impact of uncertainties on the multicentennial response of the Antarctic ice sheet. On the other hand, we contribute new methods for uncertainty quantification of geometrical characteristics of the spatial response of physics-based computational models, with, as a motivation in glaciology, a focus on predicting with quantified uncertainty the retreat of the grounded region of the Antarctic ice sheet. For the first contribution, we carry out new probabilistic projections of the multicentennial response of the Antarctic ice sheet to climate change using the f.ETISh model. We apply methods from the field of uncertainty quantification to the f.ETISh model to investigate the influence of several sources of uncertainty, namely sources of uncertainty in atmospheric forcing, basal sliding, grounding-line flux parameterisation, calving, sub-shelf melting, ice-shelf rheology, and bedrock relation, on the continental response on the Antarctic ice sheet. We provide new probabilistic projections of the contribution of the Antarctic ice sheet to future sea-level rise; we carry out stochastic sensitivity analysis to determine the most influential sources of uncertainty; and we provide new probabilistic projections of the retreat of the grounded portion of the Antarctic ice sheet. For the second contribution, we propose to address uncertainty quantification of geometrical characteristics of the spatial response of physics-based computational models within the probabilistic context of the random set theory. We contribute to the development of the concept of confidence sets that either contain or are contained within an excursion set of the spatial response with a specified probability level. We propose a new multifidelity quantile-based method for the estimation of such confidence sets and we demonstrate the performance of the proposed method on an application concerned with predicting with quantified uncertainty the retreat of the Antarctic ice sheet. In addition to these two main contributions, we contribute to two additional pieces of research pertaining to the computation of Sobol indices in global sensitivity analysis in small-data settings using the recently introduced probabilistic learning on manifolds (PLoM) and to a multi-model comparison of the projections of the contribution of the Antarctic ice sheet to global mean sea-level rise. / Les progrès récents effectués dans la modélisation de la dynamique de la calotte polaire de l'Antarctique ont donné lieu à un changement de paradigme vis-à-vis de la perception de la calotte polaire de l'Antarctique face au changement climatique. Une meilleure compréhension de la dynamique de la calotte polaire de l'Antarctique suggère désormais que la réponse de la calotte polaire de l'Antarctique au changement climatique sera déterminée par des mécanismes d'instabilité dans les régions marines. Tandis qu'un nouvel engouement se porte sur une meilleure compréhension de la réponse de la calotte polaire de l'Antarctique au changement climatique, un intérêt particulier se porte simultanément vers le besoin de quantifier les incertitudes sur l'évolution de la calotte polaire de l'Antarctique ainsi que de clarifier le rôle joué par les incertitudes sur le comportement de la calotte polaire de l'Antarctique en réponse au changement climatique. D'un point de vue numérique, les modèles glaciologiques dits essentiels ont récemment été développés afin de fournir des modèles numériques efficaces en temps de calcul dans le but de réaliser des simulations à grande échelle et sur le long terme de la dynamique des calottes polaires ainsi que dans l'optique de coupler le comportement des calottes polaires avec des modèles globaux du sytème terrestre. L'efficacité en temps de calcul de ces modèles glaciologiques essentiels, tels que le modèle f.ETISh (fast Elementary Thermomechanical Ice Sheet) développé à l'Université Libre de Bruxelles, repose sur une modélisation des mécanismes et des rétroactions essentiels gouvernant la thermodynamique des calottes polaires au travers de modèles d'ordre réduit et de paramétrisations. Vu l'efficacité en temps de calcul des modèles glaciologiques essentiels, l'utilisation de ces modèles en complément des méthodes du domaine de la quantification des incertitudes offrent de nombreuses opportunités afin de mener des analyses plus complètes de l'impact des incertitudes dans les modèles glaciologiques ainsi que de développer de nouvelles méthodes du domaine de la quantification des incertitudes dans le cadre de la modélisation glaciologique. Les contributions de cette thèse sont doubles. D'une part, nous contribuons à une nouvelle estimation et une nouvelle compréhension de l'impact des incertitudes sur la réponse de la calotte polaire de l'Antarctique dans les prochains siècles. D'autre part, nous contribuons au développement de nouvelles méthodes pour la quantification des incertitudes sur les caractéristiques géométriques de la réponse spatiale de modèles physiques numériques avec, comme motivation en glaciologie, un intérêt particulier vers la prédiction sous incertitudes du retrait de la région de la calotte polaire de l'Antarctique en contact avec le lit rocheux. Dans le cadre de la première contribution, nous réalisons de nouvelles projections probabilistes de la réponse de la calotte polaire de l'Antarctique au changement climatique au cours des prochains siècles à l'aide du modèle numérique f.ETISh. Nous appliquons des méthodes du domaine de la quantification des incertitudes au modèle numérique f.ETISh afin d'étudier l'impact de différentes sources d'incertitude sur la réponse continentale de la calotte polaire de l'Antarctique. Les sources d'incertitude étudiées sont relatives au forçage atmosphérique, au glissement basal, à la paramétrisation du flux à la ligne d'ancrage, au vêlage, à la fonte sous les barrières de glace, à la rhéologie des barrières de glace et à la relaxation du lit rocheux. Nous réalisons de nouvelles projections probabilistes de la contribution de la calotte polaire de l'Antarctique à l'augmentation future du niveau des mers; nous réalisons une analyse de sensibilité afin de déterminer les sources d'incertitude les plus influentes; et nous réalisons de nouvelles projections probabilistes du retrait de la région de la calotte polaire de l'Antarctique en contact avec le lit rocheux.Dans le cadre de la seconde contribution, nous étudions la quantification des incertitudes sur les caractéristiques géométriques de la réponse spatiale de modèles physiques numériques dans le cadre de la théorie des ensembles aléatoires. Dans le cadre de la théorie des ensembles aléatoires, nous développons le concept de régions de confiance qui contiennent ou bien sont inclus dans un ensemble d'excursion de la réponse spatiale du modèle numérique avec un niveau donné de probabilité. Afin d'estimer ces régions de confiance, nous proposons de formuler l'estimation de ces régions de confiance dans une famille d'ensembles paramétrés comme un problème d'estimation de quantiles d'une variable aléatoire et nous proposons une nouvelle méthode de type multifidélité pour estimer ces quantiles. Finalement, nous démontrons l'efficacité de cette nouvelle méthode dans le cadre d'une application relative au retrait de la région de la calotte polaire de l'Antarctique en contact avec le lit rocheux. En plus de ces deux contributions principales, nous contribuons à deux travaux de recherche additionnels. D'une part, nous contribuons à un travail de recherche relatif au calcul des indices de Sobol en analyse de sensibilité dans le cadre de petits ensembles de données à l'aide d'une nouvelle méthode d'apprentissage probabiliste sur des variétés géométriques. D'autre part, nous fournissons une comparaison multimodèle de différentes projections de la contribution de la calotte polaire de l'Antarctique à l'augmentation du niveau des mers. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

[ES] Este trabajo tiene como objetivo investigar los métodos de conservación in situ aplicables a los hallazgos arqueológicos de los loberos-balleneros, los cuales están compuestos por material proveniente del archipiélago Shetland del Sur (Antártida Occidental). Los loberos-balleneros fueron marineros llevados al territorio por compañías de caza de mamíferos marinos en los siglos XVIII y XIX. Esos cazadores habitaban temporalmente en refugios construidos en la Antártida. Las huellas que dejaron se caracterizan por la presencia de materiales muy frágiles, que se conservan debido a las condiciones ambientales particulares del continente antártico. Desde la primera expedición de excavación hecha por el Laboratorio de Estudios Antárticos en Ciencias Humanas de la Universidad Federal de Minas Gerais (Leach), en 2010, un eje de investigación ha estado articulando la metodología de excavación a la conservación in situ. Este eje ha dado paso a este proyecto de investigación doctoral desarrollado en la Universitat Politècnica de València. / [CA] Aquest treball té com a objectiu investigar els mètodes de conservació in situ aplicables a lestroballes arqueològiques dels loberos-balleners, els quals estan compostos per material provinent de l'arxipèlag Shetland de Sud (Antàrtica Occidental). Els loberos-balleners van ser mariners duts al territori per companyies de caça de mamífers marins en els segles XVIII i XIX. Aquests caçadors habitaven temporalment en refugis construïts a l'Antàrtica. Les petjades que van deixar es caracteritzen per la presència de materials molt fràgils, que només es conserven a causa de les condicions ambientals particulars del continent antàrtic. Des de la primera expedició d'excavació feta pel Laboratori d'Estudis Antàrtics en Ciències Humanes de la Universitat Federal de Mines Gerais (Leach), el 2010, un eix d'investigació ha estat articulant la metodologia d'excavació a la conservació in situ. Aquest eix ha donat pas a aquest projecte de recerca doctoral desenvolupat a la Universitat Politècnica de València. / [EN] The proposal aims investigate the methods of the in situ preservation of the whalers' archaeological remains, concerning to the South Shetland Archipelago (Occidental Antarctica). The whalers were sailors taken to the territory by companies hunting of marine mammals of the 18th and 19th centuries. These hunters lived temporarily in shelters made in Antarctica. These traces are characterized by the presence of very fragile materials, that only preserved by the specific environmental conditions provided by the Antarctic context. Since the first excavation expedition made by of the Antarctic Studies Laboratory in Human Sciences of the Federal University of Minas Gerais (Leach) in 2010, an axis of investigation is articulating the methodology excavation with the in situ conservation, which has become this PhD research project, developed together with the Universitat Politècnica de València. / La investigación ha recibido apoyo de la FAPEMIG, Fundação de Amparo à Pesquisa do Estado de Minas Gerais (Proyecto APQ 01366-17), del PROANTAR, Programa Antártico Brasileiro, y se ha llevado a cabo gracias al Programa de Doutorado Pleno no Exterior da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior‒CAPES (Brasil), por medio del Programa de Doutorado Pleno no Exterior de 2015. / De Alkmim Radicchi, G. (2022). Conservación in situ en el Proyecto Arqueología Antártica. Desafíos bajo el paralelo 60°S [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/182647 / TESIS

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The natural environments of organisms present a multitude of biotic and abiotic challenges that require both short-term ecological and long-term evolutionary responses. Though most environmental response studies have focused on effects at the ecosystem, community and organismal levels, the ultimate controls of these responses are located in the genome of the organism. Soil nematodes are highly responsive to, and display a wide variety of responses to changing environmental conditions, making them ideal models for the study of organismal interactions with their environment. In an attempt to examine responses to environmental stress (desiccation and freezing), genomic level analyses of gene expression during anhydrobiosis of the Antarctic nematode Plectus murrayi was undertaken. An EST library representative of the desiccation induced transcripts was established and the transcripts differentially expressed during desiccation stress were identified. The expressed genome of P. murrayi showed that desiccation survival in nematodes involves differential expression of a suite of genes from diverse functional areas, and constitutive expression of a number of stress related genes. My study also revealed that exposure to slow desiccation and freezing plays an important role in the transcription of stress related genes, improves desiccation and freezing survival of nematodes. Deterioration of traits essential for biological control has been recognized in diverse biological control agents including insect pathogenic nematodes. I studied the genetic mechanisms behind such deterioration using expression profiling. My results showed that trait deterioration of insect pathogenic nematode induces substantial overall changes in the nematode transcriptome and exhibits a general pattern of metabolic shift causing massive changes in metabolic and other processes. Finally, through field observations and molecular laboratory experiments the validity of the growth rate hypothesis in natural populations of Antarctic nematodes was tested. My results indicated that elemental stoichiometry influences evolutionary adaptations in gene expression and genome evolution. My study, in addition to providing immediate insight into the mechanisms by which multicellular animals respond to their environment, is transformative in its potential to inform other fundamental ecological and evolutionary questions, such as the evolution of life-history patterns and the relationship between community structure and ecological function in ecosystems.