Variabilidade climática é um sistema complexo gerado pela participação de diversos atores e sua atuação na dinâmica atmosférica, a (TSM) Temperatura da Superfície do Mar tem papel fundamental de influencia nas diversas características dos índices climáticos: Southern Hemisphere Anular Mode Index (SAM), Southern Oscillation Index (SOI), El Nino / Oscilação Sul (ENSO), (TNA) Tropical North Atlantic Index, (PDO) Pacific Decada Oscillation, North Atlantic Oscillation Index (NAO). Os Índices com variações climáticas e suas implicações, possuem um espectro de atuação e formação do clima, que se inicia nos macro-sistemas através de suas influências extraterrestres, pelos períodos de atividade solar e outros, que nos convidam a buscar um melhor entendimento sobre o clima e suas forças resultantes. Portanto essa é uma pesquisa simplista, procura demonstrar os entes envolvidos nos processos de variabilidade climática, realçando muito mais o papel dos oceanos e sua influencia de correlação sobre os regimes fluviométricos, estimando definir também a sua grande importância e um melhor entendimento do ciclo hidrológico da escala espaço-temporal na região da bacia Amazônica, partindo de uma leitura do sistema atmosférico e sua influencia dinâmica resultante sobre o ciclo hidrológico. A pesquisa adquiriu através da (ANA) Agencia Nacional de Águas os dados de vazão fluvial dos rios Solimões/Amazonas e Negro, e junto ao Earth System Research Laboratory Physical Sciences Division da NOAA, foram adquiridos os valores de TSM e Índices climáticos, já para os dados de precipitação foram solicitados junto Centro de Previsão de Tempo e Estudos Climáticos (CPTEC/INPE). Todos estes dados foram tratados em processamento no Software GrADS e ainda compilados em FORTRAN, para a analise estatística através de (R) Analise e Planejamento de Experimentos, para fornecer os dados de correlação linear, Test-t e regressão linear com o objetivo de sustentar e apoiar a analise dos resultados que possam prognosticar a partir da defasagem entre as variáveis TSM e o comportamento resultante da vazão fluvial. / Climate variability is a complex system generated by the participation of various actors and their role in atmospheric dynamics, the Sea Surface Temperature(SST) plays a key role in influencing the several features of the climate indexes: Southern Hemisphere Cancel Index Mode (SAM), Southern Oscillation Index (SOI), El Nino / Southern Oscillation (ENSO), (TNA) Tropical North Atlantic Index (PDO) Pacific Decade Oscillation, North Atlantic Oscillation Index (NAO). The climate changes indexes and their implications have a spectrum in the activity and formation of the climate, which begins in macro-systems through their extraterrestrial influences, during periods of solar activity and others, who urges us to search a better understanding of the climate and its resultant forces. Therefore, this is a simplistic research, seeking to show the entities involved in the climate variability processes, emphasizing much more the role of the oceans and its influence on the fluvial routines correlation, and estimating also define a major and also a better understanding of the hydrological cycle spatiotemporal scale in the region of the Amazon basin, starting from a reading of the atmospheric system and its resulting dynamic influence on the hydrological cycle, acquired through this research (ANA) National Water Agency data flow of the rivers Solimões / Amazonas and Negro River, and with the Earth System Research Laboratory - Physical Sciences Division of NOAA, which acquired values of SST and climate indexes. The precipitation data was requested from Center for Weather Forecasting and Climate Studies (CPTEC / INPE). All these data were processed in the processing software GrADS and also compiled in FORTRAN for statistical analysis using (R) - Analysis and Design of Experiments, to provide data for linear correlation, T-test and linear regression in order to sustain and support the analysis of the results which could predict from the discrepancy between the SST variables and the resulting conduct of river flow.

O objetivo desta pesquisa foi investigar a relação linear existente entre a Temperatura de Superfície do Mar (TSM) dos oceanos Pacífico e Atlântico e a vazão do rio Madeira, localizado na parte sul da região Norte do Brasil. A investigação foi feita nas escalas mensal, sazonal e anual, para o período de 1968 a 2009. A hipótese de que alterações climáticas na região Norte do Brasil estariam associadas a episódios de aquecimento e resfriamento dos oceanos globais, já que quando ocorrem têm o potencial de modificar o padrão de precipitação em áreas remotas do globo, foi a motivação central da pesquisa. A pesquisa foi desenvolvida com base em análises estatísticas para os dados de TSM, índices climáticos e a vazão do rio Madeira. Observou-se que a vazão mensal do rio Madeira apresenta correlação linear significativa com áreas específicas dos oceanos Atlântico e Pacífico. No Oceano Atlântico Norte, são significativas as correlações obtidas nos setores tropical (área AT3) e norte (área AT1). O setor subtropical do Atlântico Norte (AT2) apresenta correlações lineares não tão expressivas como suas áreas tropical e norte. O Atlântico Sul não apresenta áreas com correlações lineares significativas com a vazão. As áreas com correlação significativa do Atlântico Norte (AT1) apresentam valores negativos máximos entre -0,6 e -0,4. Os valores de correlação linear entre a vazão mensal do rio Madeira e a TSM do Atlântico (AT2) apresentam um pequeno aumento para os cálculos realizados com defasagem temporal de até nove meses, entre 0,3 a 0,4 para 5 meses de defasagem entre a vazão e a TSM. A TSM do setor oeste do Pacífico tropical apresenta fortes valores negativos de correlação linear com a vazão do rio Madeira, com valores máximos que variam entre -0,7 e -0,4. Tal qual acontece para o Atlântico, as águas superficiais do Pacífico tropical oeste apresentam um pequeno aumento dos valores de correlação linear para defasagens maiores entre a TSM e a vazão. As áreas com forte correlação negativa no setor oeste do Pacífico tropical foram denominadas PA1, no norte, e PA3, no sul. Uma pequena área com correlação significativa e positiva a leste da bacia do Pacífico, junto à costa do Chile, foi denominada PA2. Nesta área os valores máximos de correlação linear entre a vazão mensal e a TSM variam entre 0,2 e 0,4. A análise de correlação linear entre a vazão anual do rio Madeira e índices climáticos indicam que os índices ODP, MEI e OAN são os mais bem correlacionados com a vazão, apresentando valores iguais a 0,89, 0,86 e 0,85, respectivamente. Com base na TSM das áreas bem correlacionadas com a vazão do rio Madeira e nos índices climáticos considerados, foi desenvolvido um modelo estocástico de regressão linear múltipla para a previsão da vazão trimestral com antecedência de um trimestre. A TSM das áreas do setor oeste do Pacífico tropical, PA1, e do Atlântico Norte tropical, AT3, constituíram as variáveis selecionadas para a elaboração do modelo estocástico. O modelo estocástico foi desenvolvido para o início da série temporal considerada, de 1968 a 1988, e apresentou um ajuste linear com coeficiente de determinação igual a 78%. A verificação do modelo foi feita para o final da série, de 1989 a 2009. O erro médio normalizado calculado pela diferença entre os valores de vazão previstos pelo modelo e os observados foi igual a 40%. Desta forma, conclui-se que a vazão trimestral do setor sul da região Norte do Brasil é uma variável que pode ser prevista com base na variabilidade da temperatura das águas superficiais dos oceanos Pacífico e Atlântico. A análise do comportamento atmosférico com base em períodos específicos de anomalias de TSM no Atlântico Norte tropical indica que a ocorrência de TSMs mais altas (baixas) que o normal foram acompanhadas por ventos de leste mais fracos (fortes). Foram analisados os campos atmosféricos médios para os meses chuvosos de novembro a março para as variáveis Velocidade Vertical (Omega) em 500 e 850 hPa, divergência e vorticidade do vento. Os resultados obtidos demonstram que em média, a variabilidade atmosférica foi determinante no que se refere às anomalias apresentadas pela vazão. / The objective of this research was to investigate the linear relation between the sea surface temperature (SST) over Pacific and Atlantic oceans and the outflow of the Madeira river, located at the southern part of the Northern region of Brazil. The investigation considered monthly, seasonal and annual scales, to the period between 1968 to 2009. The consideration about the influence of heating and cooling of oceanic areas over climate around the world constitutes the main hypothesis taken in account in the study. The research was developed based on statistical analysis considering SST, climatic indexes and river outflow data. The monthly outflow for Madeira River shows significant linear correlation to SST at specific areas over Atlantic and Pacific. Over North Atlantic, the linear correlation values are significant at the tropical and north sectors, namely AT3 and AT1, respectively. The subtropical sector of North Atlantic presents positive correlation but not too expressive as the tropical and north areas of Atlantic. South Atlantic does not present significant values of linear correlation with the river outflow. The area with significant correlation over North Atlantic (AT1) presents maximum negative values ranging between -0,6 and -0,4. In general, the greater the interval between river outflow and SST data, greater is the linear correlation values. SST data from the western sector of tropical Pacific presents strong negative correlation with Madeira River outflow data, and shows maximum values ranging between -0,7 and -0,4. The areas to the West of Pacific showing high negative correlation were named PA1 and PA3, to northern and southern sectors, respectively. A small area that shows significant positive linear correlation to the river outflow data, PA2, is located over the eastern side of Pacific basin, very closed to the coast of Chile. In this area, the linear maximum correlation values range between 0,2 and 0,4. Linear correlation analysis between annual river outflow data and climatic indices indicates that PDO, MEI and NAO are those more correlated with the river outflow data, presenting values equal to 0,89, 0,86 e 0,85, respectively. Based on averaged SST and climatic indices well correlated to the Madeira River outflow data, a stochastic model was developed in order to forecast the river outflow in seasonal scale. SST from west of tropical Pacific, PA1, and from tropical North Atlantic, AT3, were selected to build up the stochastic model. The stochastic model was developed considering the first half of the total series, between 1968 and 1988, while the last period was used to validate the model, between 1989 and 2009. The linear adjusting over the first period reach a determining coefficient equal to 78% and the normalized mean error obtained for the second period was equal to 40%. Thus, we conclude that the seasonal outflow for Madeira River is a climatic variable that can be forecast based on the SST variability over specific areas on Pacific and Atlantic oceans. The analysis of atmospheric behavior based on specific periods of SST anomalies in the tropical North Atlantic indicates that the occurrence of SSTs higher (lower) than normal was accompanied by easterly winds weak (strong). We analyzed the average atmospheric fields for the rainy months from November to March for variables Vertical Speed (Omega) at 500 and 850 hPa, divergence and vorticity of the wind. The results show that approximately the atmospheric variability was decisive with regard to the deficiencies presented by the ouflow.

Made available in DSpace on 2014-08-20T14:25:47Z (GMT). No. of bitstreams: 1 dissertacao_guilherme_reinke.pdf: 5244899 bytes, checksum: 883a2f12008ef21f2da3eb9001e720b6 (MD5) Previous issue date: 2009-03-13 / The main objective of the study was to obtain the relation between Pacific and Atlantic Sea Surface Temperature (SST) anomalies and Outgoing Longwave Radiation (OLR) anomalies in South America (SA) and, moreover, evaluate the relationship of rainfall in Brazil to SST. Data from reanalysis of SST and OLR of the NCEP/NCAR were used, between the months of October and March of the period from 1982 to 2007, which was applied the statistical technique of Principal Components (PC), allowing the study of the correlation between the two variables. Data of precipitation of 691 stations in Brazil, obtained from the Instituto Nacional de Meteorologia (INMET), Agência Nacional de Águas (ANA) and Fundação Estadual de Pesquisa Agropecuária (FEPAGRO), were correlated with the scores of the SST and were used to prepare the rainfall climatology in the country, which enabled the understanding of the rainfall regime in spring and summer. Finally, a model was developed to forecast of the rainfall in Brazil with two months for advance, between December and March, using as predictors the first five scores of the SST. The correlations between the PC1 of the SST and the PC1 of the OLR shown to be significants at 1%, where the PC1 of SST is related with the ENSO pattern, showing in October: desintensification or intensification of convection in central and southern of Argentina; November: opposite pattern of OLR anomalies between south of Brazil and the area of activity of the South Atlantic Convergence Zone (SACZ); January: reduction or increase of convection in the northwestern of SA; December, February and March: intensification or desintensification of convection associated with the Bolivian High, and also in north of the North and Northeast Regions of Brazil. Moreover, in all months of the study, the PC2 of the SST showed the indication of a dipole pattern between the Central and Equatorial Atlantic adjacent to the northeastern coast of Brazil, and South Atlantic, in middle latitudes. In October, November and March, OLR anomalies areas associated with a pattern of more oceanic SACZ seem to be directly related to a strong gradient of SST anomalies, with positive anomalies in the northeast coast of Brazil and negative anomalies on the south-southeast coast of the country. When it was of the SST with the rainfall in Brazil, it was found in the months of November, December and January, similar patterns seen in the correlations between the SST and OLR. In the four months in which the model was applied to predict the rainfall, it was noted that South and Northeast regions of Brazil have the best potential for forecasting. / O principal objetivo do estudo foi obter a relação entre anomalias de Temperatura da Superfície do Mar (TSM) dos Oceanos Pacífico e Atlântico e anomalias de Radiação de Onda Longa (ROL) na América do Sul (AS) e, além disso, avaliar a relação da TSM com a precipitação no Brasil. Foram utilizados dados de reanálises de TSM e ROL do NCEP/NCAR, entre os meses de outubro a março do período de 1982 até 2007, aos quais foi aplicada a técnica estatística de Componentes Principais (CP), possibilitando o estudo da correlação entre as duas variáveis. Dados de precipitação de 691 estações no Brasil, obtidos junto ao Instituto Nacional de Meteorologia (INMET), Agência Nacional de Águas (ANA) e Fundação Estadual de Pesquisa Agropecuária (FEPAGRO), foram correlacionados com os escores da TSM e usados na elaboração da climatologia da precipitação no país, que permitiu um entendimento do regime de chuvas nos períodos de primavera e verão. Por fim, foi desenvolvido um modelo de previsão da precipitação no Brasil com dois meses de antecedência, entre dezembro e março, usando como preditores os cinco primeiros escores da TSM. As correlações entre a CP1 da TSM e a CP1 da ROL mostraram ser significativas a 1%, em que a CP1 da TSM está relacionada com o padrão ENOS, apresentando em outubro: intensificação ou desintensificação da convecção no centro e sul da Argentina; novembro: padrão oposto de anomalias de ROL entre o Sul do Brasil e a área de atuação da Zona de Convergência do Atlântico Sul (ZCAS); janeiro: redução ou aumento da convecção no noroeste da AS; dezembro, fevereiro e março: intensificação ou desintensificação da convecção associada à Alta da Bolívia e, também, no norte das Regiões Norte e Nordeste do Brasil. Além disso, em todos os meses do estudo, a CP2 da TSM mostrou no Oceano Atlântico a indicação de um padrão de dipolo entre o Atlântico Equatorial e Central adjacente à costa Nordeste do Brasil, e o Atlântico Sul, em latitudes médias. Em outubro, novembro e março, áreas de anomalias de ROL associadas com um padrão de ZCAS mais oceânica parecem estar diretamente relacionadas com um forte gradiente de anomalias de TSM, com anomalias positivas na costa nordeste do Brasil e negativas na costa Sul-Sudeste do país. Ao relacionar a TSM com a precipitação no Brasil foram encontrados nos meses de novembro, dezembro e janeiro, padrões semelhantes aos vistos nas correlações entre a TSM e ROL. Nos quatro meses em que foi aplicado o modelo de previsão da precipitação, pôde-se notar que as Regiões Sul e Nordeste do Brasil apresentam os melhores potenciais para a previsão.

Ce travail s'inscrit dans une démarche visant à quantifier l'impact de la diagenèse sur les ratios élémentaires Sr/Ca, Mg/Ca et U/Ca caractéristiques de l'exosquelette (aragonite biogénique) de coraux Porites sp. Ces ratios élémentaires sont très utilisés comme paléo thermomètres en paléo climatologie tropicale pour reconstruire les paléo variables environnementales comme la température de surface de l'océan. On considère dans un premier temps un corail moderne prélevé in vivo et un corail fossile daté au 14C de l'Holocène Moyen (5445 ans BP). Les deux coraux ne présentent aucune trace d'altération diagénétique. On mesure Sr/Ca, Mg/Ca, U/Ca dans l'exosquelette par spectrométrie de masse couplée à un plasma inductif et à la microsonde de Castaing pour Sr/Ca. Les températures de l'océan du temps du vivant des coraux sont alors reconstruites à partir de la géochimie des échantillons et validées. L'approche est ensuite étendue à des coraux pléistocènes (~125000 ans BP) altérés par la diagénèse e.g., apparition de calcite au détriment de l'aragonite initiale sous l'action de l'eau douce percolant dans les récifs. Cette calcitisation affecte les ratios Sr/Ca et Mg/Ca originels et est susceptible d'entacher les reconstructions d'un biais qu'il est important de bien connaître. En s'appuyant sur la spectrométrie Raman et la microanalyse X, on confirme les tendances qualitatives rapportées dans la littérature sur l'impact de la calcite sur les proxies du climat : la présence de calcite diminue (resp. rehausse) le ratio Sr/Ca (resp. Mg/Ca) créant donc des artéfacts chauds dans les températures reconstruites. / This work is part of an approach aimed at quantifying the impact of diagenesis upon the Sr/Ca, Mg/Ca and U/Ca elemental ratios that typify the exoskeleton (biogenic aragonite) of Porites sp corals. These elemental ratios are indeed routinely used as paleothermometers in tropical paleoclimatology in order to reconstruct environmental paleovariables such as the Sea Surface Temperature (SST). In a first step, we analyze a modern coral collected in vivo and a fossil coral dated by 14C to mid-Holocene (5545 year BP). Both corals are in pristine state. The Sr/Ca, Mg/Ca and U/Ca ratios are measured by inductively coupled plasma mass spectrometry (ICP-MS) and with a Castaing microprobe for Sr/Ca. The SSTs at the time when the corals were alive are reconstructed from the geochemistry of the samples and validated against in situ measurements / previous work in the same area. Next, the approach is extended to Pleistocene fossil corals (~125000 year BP) that have been altered by diagenesis e.g., calcitization of the samples to the detriment of the original aragonite due to the fresh water that percolates through the coral reefs. Calcitization alters the original Sr/Ca and Mg/Ca. The reconstructed SSTs can therefore include nontrivial biases whose magnitude must be evaluated. Relying on Raman spectrometry, we confirm published qualitative trends on the impact of calcite upon the climate proxies : calcite lowers (resp. increases) the Sr/Ca (resp. Mg/Ca) ratio leading therefore to warm artifacts in the reconstructed SSTs.

The major aim of this work is to develop a framework for the estimation of Evapotranspiration (ET) over the Indian landmass using remote sensing (RS) datasets in a repeated and consistent manner with improved spatial resolution. Different RS based ET models exist in the literature, out of which, the triangle, the S-SEBI and the Sim-ReSET models were compared for the estimation of daytime integrated latent heat flux (λEday). These three models were chosen as they can be driven only with RS based inputs without the need for any ground measurements. The results showed that the application of simpler contextual models may yield better results than physically based models when ground data is limited or not available. To improve the spatial resolution of one of the key surface variable, Land Surface Temperature (LST), the performance of five different vegetation indices Normalised Difference Vegetation Index (NDVI), Fraction Vegetation Cover (FVC), Normalised Difference Water Index (NDWI), Soil Adjusted Vegetation Index (SAVI) and Modified SAVI (MSAVI) were tested in the existing DisTrad disaggregation model. Results suggested that the most commonly used vegetation indices NDVI and FVC yielded better results only under wet conditions. Under drier surface conditions, using NDWI for disaggregation resulted in relatively higher accurate LST. A model for spatial disaggregation of Evaporative Fraction (EF) called DEFrac (Disaggregation of Evaporative Fraction) was developed based on the relationship between EF and NDVI to obtain finer spatial resolution EF from coarser resolution estimates. The experimental results suggested that the DEFrac model developed in this study, yielded more accurate disaggregated EF. The disaggregated EF was further used to get disaggregated λEday. Finally, The issue of lack of proper ET dataset over India was addressed by developing two data products one over entire India at 0.05° spatial resolution and the second product over the Kabini basin at 1 km spatial resolution. Both the products were developed with a temporal resolution of 8-day and for the period 2001–2014. The developed ET products were validated against ground observed data at seven sites across India and against ET simulated by a hydrological model over a forested watershed. Further the developed ET products were compared with some other global ET products such as MOD16, LandFlux Eval synthesis ET and GLEAM ET. Analyses revealed that only in regions where ET is predominantly driven by rainfall and where irrigation is not applied at very large scales, the global ET products tend to capture the ET patterns satisfactorily. On the other hand, the ET products developed in this work captured the spatial and temporal patterns of ET quite realistically all across India.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / Extreme climatic events have been occurring with greater intensity and/or frequency over South America. Indicatives for these alterations encompass natural climate variability, land use (deforestation and urbanization), global warming, and increase of greenhouse gases and aerosols in the atmosphere. South America receives a great input of moisture from the Amazon rainforest, as well as a 37% contribution from the Atlantic Ocean. Considering the whole planet, some atmospheric events need to be analyzed when regarding moisture input towards a continent. Ocean circulation can interfere for example in sea surface temperature (SST), either influencing or not the input of moisture to the continent. The objective of the present study was to analyze the variability of atmospheric moisture in South America and its extreme values, as well as the relationships with the sea surface temperature of the adjacent oceans. The present study made use of ECMWF data, ERA-INTERIM reanalysis (pressure at sea level and surface pressure, evaporation, air and dew point temperatures at 2 meters, and zonal and meridional wind at 10 meters) and also sea surface temperature data from the MetOffice Hadley Centre (HADISST). The analysis period of the present study was between 1980 and 2009, encompassing a period of 30 years of data. First, climatology, trends and extremes of moisture and evaporation (frequency, intensity and reoccurrence of events) were calculated. These were followed by lagged compositions to assess the role of sea surface temperature anomalies during extreme moisture and evaporation events. The main results found were regarding an increase of the pressure at sea level gradient and SST in the southwestern Atlantic, increase evaporation in the eastern and northern coasts of South America, and its decrease in the center-southern region of the continent. Moreover, the center-southern region also demonstrated a decrease of dew point temperature and specific moisture, and an increase in the difference between air temperature and dew point temperature. Decrease in the moisture flow magnitude and intensification of dry events over the center-southern region of South America were also observed. Finally, results showed that an SST anomaly cycle during an extreme event in the continent lasted approximately five months and, at least one month prior to the event, signs of this SST anomaly were already observable. In summary, the most significant moisture alterations in South America were found in the center-southern sector of the continent and over the southwestern Atlantic Ocean, near the Brazil-Malvinas Confluence (BMC). Nevertheless, more studies are needed to understand the relationships between SST at the BMC and moisture extremes, particularly in the center-southern portion of South America. / Atualmente os eventos climáticos extremos têm ocorrido com maior intensidade e/ou frequência sobre a América do Sul. Os indicativos para essas alterações circundam a variabilidade natural do clima, uso da terra (desmatamento e urbanização), aquecimento global, aumento da concentração de gases do efeito estufa e aerossóis na atmosfera. A América do Sul recebe um grande aporte de umidade pela existência da floresta Amazônica em seu território e também cerca de 37% de contribuição oriunda do Oceano Atlântico. Considerando todo o globo terrestre, alguns dos eventos atmosféricos precisam ser analisados com relação ao aporte de umidade sobre o continente. Com relação ao oceano, a circulação dos oceanos podem interferir, por exemplo, na temperatura da superfície do mar (TSM), influenciando ou não no aporte de umidade para o continente. O objetivo do presente trabalho foi analisar a variabilidade da umidade atmosférica na América do Sul e de seus valores extremos e as relações com a temperatura da superfície do mar nos oceanos adjacentes. O presente trabalho utilizou dados do ECMWF, da reanálise do ERA-INTERIM (pressão ao nível do mar e pressão em superfície, evaporação, temperatura do ar e temperatura do ponto de orvalho a 2 metros e vento zonal e meridional a 10 metros) e também dados de temperatura da superfície do mar do MetOffice Hadley Centre (HADISST). O período de análise do presente trabalho foi de 1980 a 2009, compreendendo um período de 30 anos de dados. Primeiramente foram calculadas as climatologias, as tendências e os extremos de umidade e evaporação (frequência, intensidade e recorrência dos eventos). Posteriormente, foram realizadas as composições defasadas para verificar o papel das anomalias da temperatura da superfície do mar durante os eventos extremos de umidade e evaporação. Os principais resultados encontrados foram em relação a um aumento da pressão ao nível do mar e da TSM no Atlântico sudoeste, aumento também da evaporação na costa leste e norte da América do Sul, e sua diminuição na região centro-sul do continente. Além disso, a região centro-sul também demonstrou uma diminuição da temperatura do ponto de orvalho e da umidade específica, e um aumento na diferença entre a temperatura do ar e a temperatura do ponto de orvalho. Diminuição da magnitude do fluxo de umidade e intensificação de eventos extremos secos sobre a região centro-sul da América do Sul também foram observados. E por fim, os resultados mostraram que um ciclo de anomalia de TSM durante um evento extremo no continente durou aproximadamente cinco meses e, pelo menos um mês antes do evento, sinais da anomalia de TSM já era observada. Em suma, as alterações mais significativas na umidade sobre a América do Sul foram encontradas no setor centro-sul do continente e sobre o Oceano Atlântico sudoeste, próximo a Confluência Brasil-Malvinas (CBM).

Durant cette thèse, les difficultés rencontrées pour la mesure de température de surface des composants métalliques face au plasma dans les tokamaks sont présentés. Les méthodes de thermographie infrarouge nécessitent de connaitre l'émissivité du matériau et la contribution de l'environnent pour les matériaux de faible émissivité. Des méthodes ont été développées afin de s'affranchir de ces difficultés mais elles répondent à des configurations particulières et aucune n'est adaptée pour une mesure de température de surface de matériaux métalliques dans un tokamak.La méthode de pyrométrie active présentée dans cette étude réalise des mesures de température de surface indépendamment du flux réfléchi et de l'émissivité en utilisant l'effet photothermique. La validation de cette technique en laboratoire sur des matériaux métalliques avec un flux réfléchi pour les régimes impulsionnel et modulé s'est accompagnée d'une modélisation de la variation de température induite par l'effet photothermique et de l'évolution temporelle des signaux obtenus pour optimiser les paramètres de la source et de la chaine d'acquisition. Les résultats expérimentaux ont déterminé les domaines d'application en température et en longueur d'onde de détection.Le dimensionnement d'une installation de pyrométrie active sur tokamak avec une caméra infrarouge bicolore a été réalisé pour une mesure de température sans contact.La méthode de pyrométrie active est une technique complémentaire des méthodes classiques utilisées dans le cadre de la thermographie en environnement tokamak qui permet de réaliser des mesures de température de surface locale et 2D indépendantes du flux réfléchi et de l'émissivité. / During this PhD, the challenges on the non-intrusive surface temperature measurements of metallic plasma facing components in tokamaks are reported. Indeed, a precise material emissivity value is needed for classical infrared methods and the environment contribution has to be known particularly for low emissivities materials. Although methods have been developed to overcome these issues, they have been implemented solely for dedicated experiments. In any case, none of these methods are suitable for surface temperature measurement in tokamaks.The active pyrometry introduced in this study allows surface temperature measurements independently of reflected flux and emissivities using pulsed and modulated photothermal effect. This method has been validated in laboratory on metallic materials with reflected fluxes for pulsed and modulated modes. This experimental validation is coupled with a surface temperature variation induced by photothermal effect and temporal signal evolvement modelling in order to optimize both the heating source characteristics and the data acquisition and treatment. The experimental results have been used to determine the application range in temperature and detection wavelengths.In this context, the design of an active pyrometry system on tokamak has been completed, based on a bicolor camera for a thermography application in metallic (or low emissivity) environment.The active pyrometry method introduced in this study is a complementary technique of classical infrared methods used for thermography in tokamak environment which allows performing local and 2D surface temperature measurements independently of reflected fluxes and emissivities.

Les opérations de maintenance des routes en conditions hivernales sur réseaux routiers constituent un enjeu important pour maintenir l’offre de mobilité en situation dégradée. Elles génèrent des coûts d’exploitation directs et indirects élevés, liés en particulier à l’utilisation intensive de fondants routiers. Par ailleurs, leur impact environnemental doit être pris en considération. Nous étudions ici une structure de chaussée non soumise à ce type d’astreinte, grâce à la présence d’une couche de liaison drainante dans laquelle circule un fluide chaud, permettant ainsi d’éviter le dépôt de neige ou la formation de glace en surface. Dans le cadre d’une démarche en faveur de l’emploi d’énergie renouvelable, un tel dispositif pourrait permettre de récupérer l’énergie thermique disponible en surface de chaussée en période chaude, de l’acheminer vers un lieu de stockage (ex : géothermie) et de l’utiliser en période froide. Nous étudions ici la fonction d’échangeur de chaleur entre le fluide et la chaussée, la fonction de stockage externe à la chaussée n’étant pas abordée hormis dans la revue bibliographique. La structure de chaussée considérée comporte trois couches d’enrobés. La couche de roulement et la couche de base sont constituées de matériaux classiquement utilisés dans les chaussées, à base de liants hydrocarbonés. Le matériau de la couche de liaison possède une porosité supérieure à 20%. La structure de chaussée est supposée avoir un dévers de l’ordre de 2%. Une chaussée expérimentale instrumentée a été mise en oeuvre pour recueillir des grandeurs thermo-physiques de la chaussée. Un modèle thermo-hydrique 2D est d2veloppé numériquement pour calculer la distribution de température dans le corps de chaussée lorsque l’on injecte un fluide à température d’entrée donnée, en haut de dévers. Les paramètres du modèle sont identifiés à partir des données expérimentales recueillies sous diverses sollicitations climatiques. On analyse dans un premier temps la sensibilité de la distribution de température en surface de chaussée aux différents paramètres du modèle (conductivité hydraulique, dévers, conductivités thermiques, chaleurs massiques), afin d’optimiser les procédures nécessaires au contrôle sous contraintes de températures positives en tout point. Dans une deuxième partie, des données expérimentales recueillies durant une période estivale d’un mois ont servi à valider le modèle thermique 1D. Une maquette de laboratoire a également permis d’identifier des paramètres en milieu saturé et non saturé. La dernière partie de thèse est consacrée au calcul des quantités énergétiques récupérables pendant la période estivale à l’aide des données de la réglEmentation thermique RT2012. Elles sont comparées aux quantités énergétiques de chauffage nécessaires pendant la période hivernale en s’appuyant sur des données de la RT2012 et des données de la Direction Interdépartementale des Routes Massif (DIR MC) ; l’objectif final étant de déterminer les performances énergétiques du système. / Winter maintenance operations for road networks are an important issue for maintaining the mobility in degraded situations, but generate high direct and indirect exploitation costs, particularly related to the intensive use of road de-icing and environmental impact. We study a road structure free of this penalty, thanks to a bonding drainage asphalt layer, circulated by a hot fluid, to prevent the deposition of snow or ice formation on the road surface. As part of an integrated vision of promoting the use of renewable energy, such device could be used to recuperate the thermal energy available in the road surface during the hot period, to transport it to a storage location (e.g. geothermal) and use it during cold period. We study here the heat exchanger function between the fluid and the road, the external storage function to the road being not addressed. The considered pavement structure has three asphalt layers.The bearing layer and the base layer are formed of conventional materials with hydrocarbon-based binders. The material of the bonding layer has a porosity of 20% and based on the use of a binder resistant to a prolonged circulation of the coolant. The road structure is assumed to have a slope of about 2 to 3%. An instrumented experimental road is implemented to collect data on the thermo-hydraulic response of the pavement structure. A thermo-hydraulic 2D model is designed to simulate the temperature field in the road structure when the fluid is injected at the upslope side of the road with a target temperature. This model is calibrated from experimental data collected on the experimental road subjected to meteorological solicitations. Initially, the sensibility of the distribution of the surface temperature of the road toward various model parameters (hydraulic conductivity, transversal slope, thermal conductivities, heat capacities) is analysed, in order to study the optimization of control procedures allowing to keep positive the road surface temperature at any point (e.g. determination of the minimum fluid injection temperature, under given meteorological data). In a second time, pavement thermal parameters is identified using control optimal method in order to validated unidimensionnel thermal model applied on July experimental data. In third time, hydraulic model is validated experimentaly using a laboratory mockup in saturated and unsaturated conditions. In a fourth time, thermo-hydraulic bidimensionnal model is validated numerically using mesured data of experimental pavement. Finally, harvest energy in summer period using thermal reglementation RT2012 data and heating energy in winter period using RT2012 and Massif Interdepartmental Road Direction (DIR MC) are calculated in order to evaluate system performance.

La situation en Antarctique est complexe. Continent peu connu et isolégéographiquement,les processus qui contrôlent son bilan de masse et son bilan d'énergie sont encore mal compris. Dans ce contexte, l'étude de la température de surface connaît un intérêt grandissant de la part de la communauté scientifique. En effet, en contrôlant fortement la température de la neige jusqu'à des dizaines, voire des centaines, de mètres sous la surface, la température de surface influence l'état thermique de la calotte du plateau antarctique, sa dynamique et, par conséquent, son bilan de masse. De plus, en agissant sur les émissions de flux thermiques infrarouges et sur les flux turbulents de chaleurs sensibles et latents, la température de surface est directement liée au bilan énergétique de surface du plateau antarctique. L'analyse de la température de surface et l'étude des processus physiques à l'origine de sa variabilité participent à l'amélioration de la compréhension du bilan énergétique de surface, étape nécessaire pour déterminer l'état actuel de sa calotte et faire des prévisions sur sa potentielle contribution à l'élévation du niveau des mers. Ce travail de thèse participe à cet effort en s'intéressant au cycle diurne de la température de surface et aux différents facteurs contribuant à sa variabilité spatiale et temporelle sur le plateau antarctique. Il débute par une évaluation de différentes données entre 2000 et 2012 montrant le bon potentiel de la température de surface MODIS qui peut dès lors être utilisée comme donnée de référence pour l'évaluation des modèles et réanalyses. Un biais chaud systématique de 3 à 6°C dans la réanalyse ERA-interim de la température de surface est ainsi mis en évidence sur le plateau antarctique. L'observation du cycle diurne de la température de surface a, quant à elle, permis d'identifier la densité superficielle parmi ses facteurs de variabilité. Sur les premiers centimètres du manteau neigeux où se concentrent la majorité des échanges de masse et d'énergie entre l'atmosphère et la calotte antarctique, la densité de la neige est une donnée cruciale car elle agit sur l'absorption du rayonnement solaire dans le manteau neigeux mais également sur la conductivité thermique du manteau et donc sur la propagation de la chaleur entre la surface et les couches en profondeur. La densité superficielle de la neige présente cependant de nombreuses incertitudes sur sa variabilité spatio-temporelle et sur les processus qui la contrôlent. De plus, ne pouvant être mesurées qu'in situ, les données de densité superficielle en Antarctique sont restreintes géographiquement. Cette thèse explore une nouvelle application de la température de surface consistant à estimer la densité superficielle de la neige via une méthode d'inversion de simulations numériques. Une carte de la densité superficielle en Antarctique a ainsi pu être produite en minimisant l'erreur de simulation sur l'amplitude diurne. / The antarctic ice sheet is a key element in the climate system and an archive of past climate variations. However, given the scarcity of observations due to the geographical remoteness of Antarctica and its harsh conditions, little is known about the processes that control its mass balance and energy. In this context, several studies focus on the surface temperature which controls the snow temperature up to tens, if not hundreds, of meters beneath the surface. It also influences the thermal state of the antarctic ice sheet, its dynamics, and thus, its mass balance. Surface temperature is also directly linked to the surface energy balance through its impact on thermal and surface turbulent heat flux emissions. Thus, surface temperature analysis and the study of physical processes that control surface temperature variability contribute to the better understanding of the surface energy balance, which is a necessary step to identify the actual state of the antarctic ice sheet and forecast its impact on sea level rise. This thesis work contributes to this effort by focusing on the surface temperature diurnal cycle and various factors impacting spatial and temporal surface temperature variability on the Antarctic Plateau. First, an evaluation of MODIS data, done by comparison with in situ measurements, shows MODIS great potential in the observation of the surface temperature of the Antarctic Plateau under clear-sky conditions. Hourly MODIS surface temperature data from 2000 to 2011 were then used to evaluate the accuracy of snow surface temperature in the ERA-Interim reanalysis and the temperature produced by a stand-alone simulation with the Crocus snowpack model using ERA-Interim forcing. It reveals that ERA-Interim has a widespread warm bias on the Antarctic Plateau ranging from +3 to +6°C depending on the location. Afterwards, observations of the surface temperature diurnal cycle allow an identification of the surface density as a factor of surface temperature variability. On the topmost centimeters of the snowpack where most mass and energy exchanges between the surface and atmosphere happen, density is critical for the energy budget because it impacts both the effective thermal conductivity and the penetration depth of light. However, there are considerable uncertainties around surface density spatio-temporal variability and the processes that control it. Besides, since surface density can only be measured in situ, surface density measurements in Antarctica are restricted to limited geographical areas. Thus, this thesis also explores a new application of surface temperature by estimating surface density in Antarctica based on the monotonic relation between surface density and surface temperature diurnal amplitude. A map of surface density is obtained by minimising the simulation error related to diurnal amplitude of the surface temperature.

Les données de télédétection dans l'infrarouge thermique (IRT) sont une source indispensable d'information pour estimer les flux de surface et suivre le fonctionnement des agro-écosystèmes. Cependant, les mesures de température de surface sont sujettes à des effets directionnels très importants (présence de 'hot spot') pouvant entraîner une erreur allant jusqu'à une dizaine de degrés Celsius. Ils doivent être pris en compte en vue des applications opérationnelles. Le travail proposé ici vise à modéliser l'anisotropie directionnelle des couverts végétaux pour mettre au point des méthodes opérationnelles de correction des mesures satellitaires de température de surface. Il est largement motivé par les projets du CNES visant à élaborer une mission spatiale nouvelle combinant une haute résolution spatiale et des capacités fortes de revisite dans l'IRT. Deux étapes de travail ont été menées. La première repose sur l'utilisation du modèle déterministe de transfert Sol-Végétation-Atmosphère SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes), capable de simuler les radiances directionnelles dans l'optique et l'IRT. Dans ce manuscrit, il est validé par rapport à des mesures de terrain et sa capacité à simuler correctement les effets d'anisotropie démontrée. Il est ensuite utilisé pour étudier de façon systématique la sensibilité de l'anisotropie directionnelle à la structure de la canopée, à son état hydrique, au forçage météorologique et aux configurations angulaires solaire et de visée. Les conséquences en terme d'impact combiné des caractéristiques orbitales des satellites, de la position géographique des sites observés et de la date d'acquisition sur l'anisotropie sont discutées. La seconde étape vise à proposer un modèle paramétrique simplifié (dit RL). SCOPE est ici utilisé en tant que générateur de données. Le modèle RL se révèle robuste et capable de restituer avec succès les signatures directionnelles sur le plan géométrique (position du hot spot) comme pour l'amplitude des effets directionnels. Une comparaison avec le seul autre modèle paramétrique utilisé jusqu'alors en télédétection IRT (le modèle de Vinnikov) confirme les qualités du modèle RL, ce qui en fait un candidat potentiel pour les chaines de traitement des futures données satellitaires. / Remotely-sensed data in thermal infrared (TIR) are an essential source of information to estimate surface fluxes and to monitor the functioning of agro-ecosystems. However, surface temperature measurements are prone to directional effects ('hot spot' phenomenon)which may result in an error up to 10°C. They have to be taken into account in the framework of operational applications. The work proposed here aims at modelling the directional anisotropy of continuous vegetated canopies in order to develop operational methods for correcting land surface temperature measurements carried out by TIR satellites. This work is mainly motivated by the CNES projects aiming at developing a new TIR spatial mission combining both high spatial resolution and high revisit time capacities. Two steps were carried out. The first is based on the use of the deterministic SVAT model SCOPE (Soil Canopy Observation, Photochemistry and Energy fluxes), able to simulate directional radiances at top of canopy in both optical and TIR domains. In this thesis, it is validated against experimental measurements and its ability to successfully simulate TIR directional anisotropy demonstrated. Then it is used to study the sensitivity of anisotropy to canopy structure, water status of soil and vegetation, meteorological forcing and solar and observer angular configurations. The consequences of the combined features of satellites orbits, geographical position of the scanned sites and acquisition date on anisotropy are discussed. In the second part, we propose a simplified parametric model (called 'RL'). SCOPE is used as a data generator. The RL model is deemed suitable and able to correctly reproduce directional signatures both in terms of geometry (hot spot position) and amplitude of these effects. A comparison with the only one parametric model previously used in TIR remote sensing (Vinnikov's approach) confirms the good capacities of the RL model. The RL model is thus a potential candidate to the future satellite processing chains.