Made available in DSpace on 2014-06-11T19:26:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-18Bitstream added on 2014-06-13T20:34:41Z : No. of bitstreams: 1 souza_ap_me_botfca.pdf: 2085223 bytes, checksum: 6f1e33f2d9020a877fb0c3f6857acac1 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / Este trabalho objetivou apresentar a evolução anual das irradiações global ( d ) G H b , direta ( d ) B H b e difusa de referência ( d ) DR H b média mensal com medidas diárias incidentes sobre superfícies inclinadas a 12,85º L − 10º , 22,85º L e 32,85º L + 10º com a face voltada para o Norte e as estimativas das três irradiações com base em medidas da irradiação global na horizontal e da razão de insolação. O periodo de dados considerado no estudo foi de 1998 a 2007, com medidas realizadas entre 04/1998 a 08/2001 para a inclinação de 22,85º; de 09/2001 a 02/2003 para 12,85º e de 01/2004 a 12/2007 para a inclinação de 32,85º. Em todos os períodos de medidas, os valores as tres irradiações foram comparadas com medidas realizadas em superfícies horizontais. Os níveis de ( d ) H Gb nos planos inclinados foram inferiores no período de verão e superiores entre os equinócios quando comparados com as superfícies horizontais. Houve uma tendência de aumento da diferença entre ( d ) H Gb e ( d ) H GH com o aumento da intensidade de inclinação. Os picos máximos médios mensais verificados nas inclinações foram de 22,04; 22,64 e 21,82 MJ m-2 dia-1, ocorridos em setembro, abril e agosto, enquanto que os picos mínimos foram de 16,08; 17,00 e 16,39 MJ m-2 dia-1 nos meses de maio, junho e janeiro, para as inclinações de L − 10º , L e L + 10º , respectivamente. Nas superfícies horizontais nesse período de medidas foram verificados máximos e minimos de 23,64 e 12,95 MJ m-2 dia-1, em novembro e junho. As radiações diretas na horizontal foram projetadas nas inclinações e foram obtidos pelo produto entre ( d ) bH H e o fator geométrico ( ) B R . Os valores de ( ) d H Bb foram inferiores aos de ( ) d H BH no verão e superiores no inverno, com diferenças crescentes com o aumento da inclinação. Os valores máximos... / This work planned to present the annual evolution of the diffuse reference, beam, and global irradiations of monthly medium with daily measures incidents about surfaces inclined to 12,85º L − 10º , 22,85º L e 32,85º L + 10º with facing the Nort and the estimates of the three irradiations on the basis of measures of the global irradiation in the horizontal one and of the reason of sunshine. The period of facts considered in the study was of 1998 to 2007, with measures carried out between 04/1998 to 08/2001 for the inclination of 22,85º; of 09/2001 to 02/2003 for 12,85º and of 01/2004 to 12/2007 for the inclination of 32,85º. In all of the periods of measures, the values the three irradiations were compared with measures carried out in horizontal surfaces. The levels of ( d ) H Gb in the planes tilters were lower in the period of summer and superiors between the equinoxes when compared with the horizontal surfaces. Had a tendency of increase of the difference between ( d ) H Gb and ( d ) H GH increase with of the intensity of inclination. The monthly medium maximum peaks verified in the inclinations were of 22,04; 22,64 e 21,82 MJ m-2, they occurred in september, april and august, whereas the most minimum peaks were of 16,08; 17,00 e 16,39 MJ m-2 in the months of may, june and january, for the inclinations of L-10º, L and L+10º, respectively. In the horizontal surfaces in that period of measures were verified maximum and minimum of 23,64 e 12,95 MJ m-2, in november and june. The direct radiations in the horizontal one were projected in the inclinations and were obtained by the product between ( d ) bH H and the geometrical factor ( ) B R . The values of ( ) d H Bb were lower to ( ) d H BH of the in the summer... (Complete abstract click electronic access below)

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-11-30T08:24:16Z No. of bitstreams: 2 Tese - Claudinei Sousa Lima - 2015.pdf: 4697944 bytes, checksum: 7602b1a52d5ff89353f1980ba35380a6 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-11-30T08:26:27Z (GMT) No. of bitstreams: 2 Tese - Claudinei Sousa Lima - 2015.pdf: 4697944 bytes, checksum: 7602b1a52d5ff89353f1980ba35380a6 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-11-30T08:26:27Z (GMT). No. of bitstreams: 2 Tese - Claudinei Sousa Lima - 2015.pdf: 4697944 bytes, checksum: 7602b1a52d5ff89353f1980ba35380a6 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-04-06 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / A real sample of textile wastewater was successfully decolorized through a simple, fast and efficient photocatalytic treatment using polypyrrole as catalyst. In the optimized operational conditions, the photocatalytic treatment resulted in 95.8% decrease in the units of color and 91.2% photodecomposition. Photocatalysis reduced the COD values from 1111.04 mg L1 to 71.43 mg L1, evidencing 93.6% reduction in the organic matter to be discharged. TOC was also efficiently reduced from 156.75 to 51.74. The efficiency of the photocatalytic process was maintained during repeated use when cycles of photocatalysis were followed by redoping of polypyrrole with 0.1 mol L1 HCl solution. The same photodecomposition efficiency was achieved using sunlight irradiation for 30 min, with values of photodecomposition up to 98%. Tests of toxicity using Artemia saline resulted in 96.7% survival, indicating that the products generated in the photodecomposition are non-toxic. Tests made with an artificial effluent showed the same efficiency in wastewater color removal indicating that the process may be suitable for treating effluents with different colors with same efficiency. In this way, photocatalytic treatment may be applied on photodecomposition of textile effluent, independent of the predominant color present in the effluent. / Uma amostra real de efluente têxtil foi descorada com sucesso através de um tratamento fotocatalítico simples, rápido e eficiente usando polipirrol como catalisador. Nas condições operacionais optimizadas, o tratamento fotocatalítico resultou em 95,8% de diminuição nas unidades de cor e 91,2% fotodecomposição. A fotocatálise reduziu os valores de Demanda Química de Oxigênio (DQO) de 1111,04 mg.L-1 para 71,43 mg.L-1, evidenciando redução de 93,6% da matéria orgânica a ser descartada nos corpos receptores. O Carbono Orgânico Total (COT) também foi reduzido de forma eficiente 156,75 - 51,74 ppm . A eficiência do processo fotocatalítico foi mantida durante o uso repetido, quando os ciclos de fotocatálise foram seguidos por redopagem do polipirrol com uma solução de HCl 0,1 mol.l-1. A mesma eficiência de fotodecomposição foi conseguida utilizando irradiação solar durante 30 minutos, com valores de fotodecomposição até 98%. Os testes de toxicidade usando Artemia salina, resultaram em 96,7% de sobrevivência, o que indica que os produtos gerados na fotodecomposição não são tóxicos. Testes feitos com o um efluente artificial mostraram a mesma eficiência na remoção da cor do efluente indicando que o processo pode ser adequado a tratar efluentes artificias que permitiriam realização de experimentos sem a interferência de variações da cor do efluente em função cor predominante produzida no dia da coleta.

This thesis aims to determine the accessible solar potential and estimation of PV installation in Bangladesh to increase solar power production concerning conventional power production in Bangladesh. The rise of renewable energy sources and especially solar energy may result in a significant contribution to the power generation system. To achieve its advantage, proper study and research are important to establish the tangible solar capacity from relevant parameters. Conventional power production depends on a variety of factors and needs to be replaced by renewable resources for the increasing demand. Solar energy is a free source of energy and Bangladesh receives a huge quantity of solar radiation due to its geographical location in the tropical zone. In this thesis, solar irradiation, PV output, and many other parameters are determined to discover the potential of solar power. After that, total land area, population, number of households from the home establishment, number of industries, untilled land area, and other related factors are thoroughly studied and calculated to establish accessible solar electricity. Economic and environmental impacts are the most important criteria of this renewable resource from the country's perspective. Cost and CO2 emission are discussed for conventional electricity production and compared to solar electricity production.

L’industrialisation et l’utilisation dans la vie courante d’un nombre croissant de produits chimiques et médicamenteux sont responsables de la dissémination dans l’environnement de substances variées nommées« polluants émergents ». Les traitements des eaux usées existants ne sont pas conçus pour éliminer cette catégorie de pollution et les polluants émergents sont alors rejetés dans le milieu récepteur. Une possible solution pour limiter le rejet de ces composés par les effluents de station d’épuration serait l’utilisation de procédés de traitement additionnels tels que les procédés d’oxydation avancés. C’est dans ce contexte qu’a démarré le projet Européen Clean Water en 2009 associant 7 entités dont le GEPEA-Ecole des Mines de Nantes. Le concept du projet est de développer des procédés photocatalytiques mettant en œuvre des nanomatériaux actifs sous la lumière solaire. Ces procédés visent à éliminer les polluants émergents tels que les perturbateurs endocriniens ou les produits pharmaceutiques. Dans ce programme, le laboratoire GEPEA est concerné par l’évaluation de l’efficacité des matériaux vis-à-vis de l’élimination des polluants émergents sous irradiations UV et visibles. Pour cela, une méthodologie expérimentale a été établie de façon à exprimer les performances des catalyseurs testés en termes de constantes cinétiques de dégradation, de taux de conversion et de minéralisation des molécules étudiées mais aussi en fonction de la formation de produits intermédiaires. Ces performances sont également évaluées en termes de biodégradabilité, d’effet de toxicité et de perturbation endocrinienne des produits intermédiaires. Dans un premier temps, la méthodologie expérimentale établie a été testée sur la dégradation de la tétracycline en utilisant un catalyseur de référence puis, elle a été appliquée sur la dégradation respective du bisphénol A et de la 17β-oestradiol en utilisant un catalyseur de référence et les catalyseurs élaborés dans le cadre du projet Clean Water. Les résultats sur la dégradation de la tétracycline ont montré que i) les intermédiaires réactionnels sont moins toxiques que la tétracycline, ii) la structure des intermédiaires réactionnelles est semblable à celle de la tétracycline ce qui explique la faible biodégradabilité de ces intermédiaires. Concernant la dégradation du bisphénol A et de la 17β-oestradiol, les résultats ont montré que i) les catalyseurs sont efficaces sous irradiation solaire simulée. Cependant, l’efficacité photocatalytique du catalyseur dépend du composé à dégrader, ii) la nature des intermédiaires réactionnels identifiés du bisphénol A dépend du catalyseur utilisé, iii) l’effet œstrogénique de la solution d’oestradiol persiste au cours du traitement photocatalytique. / Industrialisation, the use of numerous chemical products in domestic activities and the use of medicine drugs have led to the release in the environment of various substances named "emerging pollutants”. The existing wastewater treatments are not designed to eliminate this kind of pollution and then these pollutants are released into the natural aquatic media. To limit the release of these compounds by waste water treatment plant effluent, a solution could be the use of additional treatment processes such as advanced oxidation processes. In this context, the European project Clean Water has started in 2009. Clean Water involves 7 entities including the GEPEA laboratory-Ecole des Mines de Nantes. The aim of the Clean Water project is to develop sustainable and cost effective water treatment and detoxification processes using TiO2 nanomaterials with UV-visible light response under solar light. These processes act to remove emerging contaminants such as endocrine disruptors and pharmaceuticals. In this program, theGEPEA laboratory is concerned with the evaluation of the efficiency of novel photocatalysts under UV and visible irradiations for the elimination of emerging pollutants. For this purpose, an experimental methodology was established to express the efficiency of the tested catalysts in terms of degradation kinetic constants, pollutants conversion and mineralisation and also in terms of the intermediate products formed. The efficiency of photocatalysts is also evaluated in terms of intermediates biodegradability, toxicity and endocrine disruption effects. First, the experimental methodology was tested on the degradation of tetracycline with a reference catalyst. Then, it was applied to the degradation of bisphenol A and estradiol respectively with the reference catalyst and the catalysts developed within the Clean Water Project. The results obtained on the tetracycline degradation have showed that: i) tetracycline intermediate products are less toxic than tetracycline ii) the intermediates structure is similar to that of tetracycline, this can explain the low biodegradability observed for these intermediates. For the degradation of bisphenol A and estradiol, the results showed that: i) the photocatalysts are efficient under simulated solar irradiation. However, the catalyst photocatalytic efficiency depends on the compound to be degraded ii) the nature of the bisphenol A reaction intermediates identified depends on the catalyst used iii)the estrogenic effect of the estradiol treated solution persists during the photocatalytic treatment.

Ce travail rapporte l'élaboration par voies humides (sol-gel, précipitation) et sèche (mécanosynthèse) de photocatalyseurs originaux à l’état de poudre pure ou supportées sur des fibres de palygorskite (Pal), composant d’une argile brute naturelle d’origine marocaine. TiO2 seul, non dopé ou dopé au soufre, et couplé avec CuO fut utilisé comme composant actif principal. Ag2CO3 fut également étudié comme composant alternatif en raison de sa forte activité dans le domaine du visible. Ces photocatalyseurs furent testés pour la dégradation de polluants modèles anionique (orange G, OG) et cationique (rouge neutre, RN) en milieux aqueux, sous irradiation artificielle UV, Visible et Solaire, ainsi que sous ensoleillement naturel extérieur. Les caractérisations multi-échelles effectuées sur les différents photocatalyseurs développés ont essentiellement démontré : - L’immobilisation par sol-gel de nanoparticules (NPs) de TiO2 et CuO sur Pal avec formation d’hétérojonctions entre ces oxydes, produisant une activité photocatalytique sous UV avérée mais toutefois trop limitée ; - La formation par précipitation de nanocomposites à base de NPs Ag2CO3 déposées sur les fibres de Pal. Selon la durée de maintien des réactifs en digestion et un protocole de cycles thermiques couplés à du vieillissement sous atmosphère de CO2, il a été possible d’obtenir Ag2CO3 sous sa forme structurale métastable hexagonale (H) et stable monoclinique (m), ou de contrôler la proportion des 2 phases dans les composites Ag2CO3/Pal. Ces nouveaux photocatalyseurs sont actifs dans le visible et les nanocomposites biphasés H+m se sont avérés plus actifs que les monophasés. - L’élaboration par mécanosynthèse de TiO2 anatase supporté sur Pal et de TiO2 principalement anatase en coexistence remarquable avec une phase monoclinique métastable B dans le cas du dopage au soufre. TiO2-S est très actif dans le visible tandis que TiO2-Pal manifeste une activité sous UV en présentant l’avantage de pouvoir exploiter les propriétés de l’argile pour développer une multifonctionnalité (photocatalyse-adsorption). Ces photocatalyseurs sont actifs sous forme de poudres dispersés et de revêtements sous irradiation solaire. La cinétique de dégradation du polluant modèle a pu être modélisée. / This work reports the development of different photocatalysts using either wet route (sol-gel and precipitation methods) or dry route (mecanosynthesis followed by annealing). The photocatalysts are TiO2 (pure or doped with sulfur) nanoparticles (NPs), TiO2 coupled with CuO and Ag2CO3 supported on natural fibrous clay from Morocco called palygorskite (Pal). The degradation of model anionic dyes (orange G, OG) and cationic dyes (neutral red, NR) in aqueous solution were investigated under artificial radiation (UV and visible) and natural sunlight. The multi-scale chemical and structural characterization and the properties investigated on the different photocatalysts showed the following results: -Immobilization of both TiO2 and CuO NPs on palygorskite by sol-gel method. Despite the heterojunctions between these functional oxides the photocatalysts exhibit a limited activity under UV irradiation. - Elaboration of nanocomposites made of Ag2CO3 NPs deposited on Pal fibers using the precipitation method. Depending on the time of reactant digestion, the number of thermal cycles and the aging for several months, Ag2CO3 adopts remarkably, in these nanocomposites, the exclusive forms of metastable hexagonal structure (H), or the stable monoclinic one (m) or a mixture of both phases with different proportions depending on the mass ratio of Ag2CO3/Pal. All Ag2CO3-Pal nanocomposites are active in the visible range for the elimination of OG. The nanocomposites in the biphasic form H + m are more active than single phases samples either in the form H or m. - Preparation of anatase TiO2 supported on Pal and TiO2 as a mixture of mainly TiO2 anatase and a minority of a remarkable monoclinic phase B by a mechanical alloying method. The NPs surfaces of these photocatalysts are acidified by grafting the sulfate groups (SO42-) and the anionic network is lightly doped with substituting O2- by S2-. These specific characteristics have made TiO2-S very active in the visible for the degradation of OG, while TiO2-Pal composite exhibits an activity under UV. Both types of photocatalysts in the form of powders dispersed in the OG solutions have proved to be active under sunlight and as well in the form of coating. TiO2-Pal has showed allows the adsorption of cationic entities RN facilitating their subsequent photodegradation.

Cette thèse porte sur l’étude de la transformation de polluants organiques à la surface du sol sous l’effet de la lumière. Deux principaux composés organiques ont été utilisés : une molécule modèle, la phénylbenzo-quinone (PhQ) ; et un pesticide de la famille des carbamates, le carbaryl. Nous avons travaillé sur différents supports : trois supports modèles (silice, sable de Fontainebleau et kaolinite) et sur un sol de la région d’Orange. La phototransformation a été réalisée en utilisant un dispositif qui simule le rayonnement solaire (l>300nm). L’étude des propriétés spectroscopiques de PhQ sur support solide a permis de montrer un élargissement de la bande d’absorption et des effets bathochrome et hyperchrome. Lors de l’irradiation, la concentration et l’épaisseur des films se sont avérés être des paramètres importants à considérer afin de tenir compte respectivement l’effet d’écran et le phénomène de diffusion. Une valeur limite de l’épaisseur égale à 100 μm a été déterminée afin de s’affranchir du processus de diffusion. Le mécanisme de transformation de PhQ s’est avéré être identique à celui observé dans l’eau avec la formation d’un unique produit, la 2-hydroxydibenzofuranne, et la mise en évidence de l’état excité triplet de PhQ. La présence d’eau influence la phototransformation du composé en augmentant la vitesse de transformation. Ceci s’explique par une modification des propriétés d’absorption du support humide qui favorise la pénétration de la lumière. Suite à cette première étude, un travail plus complexe a été entrepris sur la photodégradation du carbaryl à la surface de supports modèles. Le coefficient d’absorption molaire sur la kaolinite et le rendement quantique de transformation ont pu être déterminés pour le carbaryl et d’autres composés organiques. Ceci nous a permis de confirmer l’effet bathochrome, l’effet hyperchrome, ainsi que l’augmentation du rendement quantique : augmentation d’un facteur 10 pour le carbaryl. Les études cinétiques ont montré que la dégradation du carbaryl est effective sur tous les supports. A l’aide des propriétés physico-chimiques des supports, nous avons pu émettre l’hypothèse que la taille des particules contrôle la photodégradation. Celle-ci est plus efficace avec des particules de grande taille, du fait de la meilleure pénétration des photons. Enfin à l’aide d’une étude analytique poussée et de la mise en évidence de la formation de HO• et 1O2, nous avons proposé un mécanisme de photodégradation impliquant des réactions de PhotoFries, de photohydrolyse, de dimérisation et d’hydroxylation. Dans la deuxième partie des travaux sur le sol réel, un protocole original a été mis en oeuvre. Il consiste en un fractionnement préalable du sol suivi d’un traitement chimique afin d’atténuer l’impact de la matière organique. Il a été montré que la dégradation sur le sol et ses fractions est efficace et que la matière organique a un effet bénéfique, à faible concentration, et inhibiteur, à forte concentration, sur la transformation du carbaryl. De plus, le fractionnement a révélé que la photodégradation est d’autant plus importante que les fractions sont constituées de particules de grande taille. Enfin, la formation d’espèces réactives (HO• et 1O2) a été observée systématiquement et plus efficacement pour les fractions sans matière organique suggérant des processus de transformation attribuables à la partie minérale des supports. / This study focuses on the transformation of organic pollutants on soil surface under the influence of the light excitation. Two main organic compounds were used as model molecules, phenylbenzoquinone (PhQ) and a carbamate pesticide, carbaryl. We used several supports : three model supports (silica, sand of Fontainebleau and kaolinite) and a real soil of the region of Orange (France). The phototransformation was carried out using a device that simulates the solar radiation (l > 300 nm). The study of the spectroscopic features of PhQ on solid support shows a broad band of absorption that presents bathochromic and hyperchromic effects. During irradiation, the concentration and the thickness of film were found to be important parameters to be considered in order to avoid the screen as well as diffusion effect. The optimal value of the thickness was determined roughly to 100 μm in order to minimise the diffusion effect. The mechanism of transformation of PhQ is similar to that observed in aqueous solution with the formation of the unique photoproduct 2-hydroxybenzofuran. The process involves the triplet excited state of PhQ. After this work, the first studies are on the phototransformation of carbaryl and other pesticides on model supports. Furthermore, the molar absorption coefficient and quantum yield have been determined in order to confirm the bathochromic and hyperchromic effect and also the increase of the quantum yield (10 times for carbaryl). The degradation process was most effective when the particle size increases. Moreover, from the analytical studies the photodegradation mechanism was suggested involving several reactions such as photofries, photohydrolyse, dimerisation and hydroxylation. The second part of the present work was dedicated to the study on real soil. An original protocol had to be set up. It consisted on a prefractionation of soil followed by a chemical treatment to minimise the impact of organic matter. Concerning the phototransformation of carbaryl, it was shown that the degradation at the surface of soil and its fractions is effective and that the organic matter has a beneficial effect at low concentrations and inhibition effect at high concentrations. Furthermore, fractionation revealed that photodegradation is more important when the fractions are composed of large particles. Finally, the formation of reactive species (HO• and 1O2) was observed consistently and efficiently for fractions without organic matter suggesting transformation processes induced by the mineral part of the supports.

Motivation | Societal and economic needs of East Africa rely entirely on the availability of water, which is governed by the regular onset and retreat of the rainy seasons. Fluctuations in the amounts of rainfall has tremendous impact causing widespread famine, disease outbreaks and human migrations. Efforts towards high resolution forecasting of seasonal precipitation and hydrological systems are therefore needed, which requires high frequency short to long-term analyses of available climate data that I am going to present in this doctoral thesis by three different studies. 15,000 years - Suguta Valley | The main study of this thesis concentrated on the understanding of humidity changes within the last African Humid Period (AHP, 14.8-5.5 ka BP). The nature and causes of intensity variations of the West-African (WAM) and Indian Summer monsoons (ISM) during the AHP, especially their exact influence on regional climate relative to each other, is currently intensely debated. Here, I present a high-resolution multiproxy lake-level record spanning the AHP from the remote Suguta Valley in the northern Kenya Rift, located between the WAM and ISM domains. The presently desiccated valley was during the AHP filled by a 300 m deep and 2200 km2 large palaeo-lake due to an increase in precipitation of only 26%. The record explains the synchronous onset of large lakes in the East African Rift System (EARS) with the longitudinal shift of the Congo Air Boundary (CAB) over the East African and Ethiopian Plateaus, as the direct consequence of an enhanced atmospheric pressure gradient between East-Africa and India due to a precessional-forced northern hemisphere insolation maximum. Pronounced, and abrupt lake level fluctuations during the generally wet AHP are explained by small-scale solar irradiation changes weakening this pressure gradient atmospheric moisture availability preventing the CAB from reaching the study area. Instead, the termination of the AHP occurred, in a non-linear manner due to a change towards an equatorial insolation maximum ca. 6.5 ka ago extending the AHP over Ethiopia and West-Africa. 200 years - Lake Naivasha | The second part of the thesis focused on the analysis of a 200 year-old sediment core from Lake Naivasha in the Central Kenya Rift, one of the very few present freshwater lakes in East Africa. The results revealed and confirmed, that the appliance of proxy records for palaeo-climate reconstruction for the last 100 years within a time of increasing industrialisation and therefore human impact to the proxy-record containing sites are broadly limited. Since the middle of the 20th century, intense anthropogenic activity around Lake Naivasha has led to cultural eutrophication, which has overprinted the influence of natural climate variation to the lake usually inferred from proxy records such as diatoms, transfer-functions, geochemical and sedimentological analysis as used in this study. The results clarify the need for proxy records from remote unsettled areas to contribute with pristine data sets to current debates about anthropologic induced global warming since the past 100 years. 14 years - East African Rift | In order to avoid human influenced data sets and validate spatial and temporal heterogeneities of proxy-records from East Africa, the third part of the thesis therefore concentrated on the most recent past 14 years (1996-2010) detecting climate variability by using remotely sensed rainfall data. The advancement in the spatial coverage and temporal resolutions of rainfall data allow a better understanding of influencing climate mechanisms and help to better interpret proxy-records from the EARS in order to reconstruct past climate conditions. The study focuses on the dynamics of intraseasonal rainfall distribution within catchments of eleven lake basins in the EARS that are often used for palaeo-climate studies. We discovered that rainfall in adjacent basins exhibits high complexities in the magnitudes of intraseasonal variability, biennial to triennial precipitation patterns and even are not necessarily correlated often showing opposite trends. The variability among the watersheds is driven by the complex interaction of topography, in particular the shape, length and elevation of the catchment and its relative location to the East African Rift System and predominant influence of the ITCZ or CAB, whose locations and intensities are dependent on the strength of low pressure cells over India, SST variations in the Atlantic, Pacific or Indian Ocean, QBO phases and the 11-year solar cycle. Among all seasons we observed, January-September is the season of highest and most complex rainfall variability, especially for the East African Plateau basins, most likely due to the irregular penetration and sensitivity of the CAB. / Motivation | Die sozialen und ökonomischen Bedürfnisse Ostafrikas sind in erster Linie von der Wasserverfügbarkeit abhängig, welche durch das regelmäßige Einsetzen der Regenzeiten bestimmt wird. Jegliche Veränderungen der Wasserverfügbarkeit innerhalb der Regenzeiten verursachen Hungersnöte, Ausbruch von Krankheiten oder auch Bevölkerungswanderungen. Klärung der Ursachen von Niederschlagsvariabilitäten erfordert die Auswertung von hochauflösenden Kurz- als auch Langzeitanalysen, welche ich in dieser Arbeit durch drei Studien präsentieren werde. 15,000 Jahre - Suguta Valley | Die Hauptstudie dieser Doktorarbeit befasste sich mit dem Verständnis von Feuchtigkeitsschwankungen innerhalb der Afrikanischen Feuchtperiode (AHP, 5.5 - 14.8 ka BP). In dieser Studie präsentiere ich einen hoch-auflösenden Seespiegel Datensatz aus dem abgeschiedenen, unbewohnten Suguta Tal im nördlichen Grabenbruch in Kenia. Das momentan extrem trockene Tal war während der AHP mit einem 300 m tiefen und 2200 km2 großen Paläo-See bedeckt, was aus nur 26% zusätzlichem Niederschlag resultierte. Diese Erhöhung wurde vermutlich aus der Kombination aus erhöhter atmosphärer Feuchteverfügbarkeit infolge erhöhter früh-Holozäner präzessionsgesteuerten Einstrahlung auf der nördlichen Hemisphere sowie der Verschiebung der feuchten Kongo Luftmassengrenze (CAB) ostwärts über das Ostafrikanische und Äthiopische Plateau erreicht als direkte Folge eines erhöhten atmosphärischen Druckgradienten. Abrupte, starkte Seespiegelschwankungen innerhalb der generellen Feuchtphase sind auf geringe Veränderungen in der solaren Ausstrahlung zurückzufühen, welche zu einer Schwächung des Druckgradienten führten und damit den Einfluss der CAB im Untersuchungsgebiet verhinderten zusammen mit einer allgemeinene Reduktion der atmosphärischen Feuchteverfügbarkeit. Das Ende der AHP erfolgte im Gegensatz dazu eher nicht-linear aufgrund des Wechsels zu einem äquatorialen Einstrahlungsmaximum vor 6.5 ka, welches die AHP in Äthiopien und West-Afrika verlängerte. 200 Jahre - Lake Naivasha | Der zweite Teil dieser Arbeit konzentrierte sich auf die Analyse eines Sedimentkern des Naivasha See aus dem zentralen Kenia Rift über die letzten 200 Jahre, einem der wenigen Frischwasserseen in Ostafrika. Die natürliche Klimavariabilität sollte mittels Proxy-Datensätzen von Diatomeen, Transferfunktionen, geochemischen und sedimentologischen Analysen in dieser Studie aufgedeckt werden. Die Ergebnisse zeigten, dass seit Mitte des 20. Jahrhundert der zunehmende Einfluss des Menschen um den Naivasha See zu kultureller Eutrophierung geführt, welche den Einfluss der natürlichen Klimavariabilität auf den See überprägte. Die Gründe liegen in der Zeit, welche von steigender Industrialisierung und deshalb erhöhtem menschlichen Einfluss auf die Proxy-Daten enthaltenden Seen geprägt ist. Die Ergebnisse verdeutlichen die Notwendigkeit von Proxy-Daten aus unbesiedelten Gebieten, wenn man ,reine‘ Daten zur momentanen Debatte über den anthropogen gesteuerten Klimawandel der letzten 100 Jahre beitragen will. 14 Jahre - Ostafrikanisches Rift | Um räumliche Unregelmäßigkeiten in Proxy-Daten von Ostafrika richtig zu verstehen, konzentrierte sich der dritte Teil dieser Arbeit auf die Auswertung von ausschließlich fernerkundlich erworbenen heutigen, täglichen Niederschlagsreihen (1996-2010). Dies erlaubt ein besseres Verständnis über die möglichen klimatischen Einflussmechanismen und die Abschätzung ihres Einflusses auf die Paläo-Variabilität. Die Studie beschäftigt sich mit der Dynamik saisonaler Niederschlagsverteilung innerhalb der Einzugsgebiete von elf Seebecken im Ostafrikanischen Riftsystem, welche oft für Paläo-Klimastudien benutzt werden. Die Studie ergab, dass Niederschläge in angrenzenden Becken tatsächlich höchst unterschiedlich in ihrer Intensität sein können und dabei zwei- bis dreijährigen Niederschlagsmuster folgen oder sogar gegensätzliche Trends zeigen. Die Variabilität der einzelnen Seebecken wird durch die komplexe Wechselwirkung der Topographie, Form, Länge und Höhe des Einzugsgebietes, der relativen Lage im EARS, sowie dem Einfluss und Intensität der ITCZ und CAB bestimmt, welche z.B. abhängig von der Entwicklung besonders starker Tiefdruckgebiet über Indien, Veränderungen der Meeres-oberflächentemperaturen, QBO und dem 11-Jahres Sonnenzyklus sind. Im direkten Vergleich aller untersuchten Monate stellte sich heraus, dass Juli-September die Jahreszeit mit komplexester Niederschlagsvariabilität ist, besonders für die Becken des Ostafrikanischen Plateau, was durch den unregelmäßigen Einfluss der CAB verursacht wird.

A energia solar fotovoltaica é uma alternativa de energia limpa que está se tornando uma importante opção para se utilizar eletricidade em regiões desprovidas de energia elétrica. Um estudo das condições energéticas da região através de consulta às concessionárias de energia elétrica (Eletricidade de Moçambique - EDM no caso de Moçambique) e do Ministério de Energia do Governo, são fontes importantes de dados para se conhecer o cenário energético de cada região. Outra fonte de dados importante para se estimar o potencial de geração de energia solar fotovoltaico sãoos indices de irradiação da região. Estes podemser obtidos através do órgão meteorológico da região (INAM no caso de Moçambique) que forneceesses dados para as principais cidades através de suas estações meteorológicas espalhadas na região. Laboratórios de pesquisa internacionais sãooutra importante fonte de dados solarimétricos, pois utilizam satélites capazes de cobrir todo globo terrestre e os dados obtidos são publicados e permitem, a partir das coordenadas do local, identificar a irradiação solar em diversos locais do mundo. Os dados desses laboratórios podem ser comparados com dados de órgãos oficiais da região. Utilizando o banco de dados solarimétricospode-se calcular o potencial fotovoltaico de geração de energia de cada localização e também definir qual região seria mais propícia a utilização de energiasolar fotovoltaica conectada à rede. / Photovoltaic solar energy is an alternative clean energy that it is becoming an important option to be used in region that it does not have available electricity. A study about energy condition of region contacting local energy company (Electricity of Mozambique EDM in the case of Moçambique) and the ministry of governmental are important resources of data to know the electric power conditions scenery of each region. Another important data resource to assesss the photovoltaic potencial of a region is to access the solarimetric data of region. It should be got from the region meteorological organ (in Mozambique it is INAM) that provides this information for main cities through its meteorological station spread across the region. Research International labs are another important resource of the data. They use satellites that are able to cover the whole terrestrial globe and make it available. These data allow applications through the coordinates of the location, identify the exact solar irradiance at any point (in the case NREL in the USA). Laboratory data should be validated through comparisons with data from the official bodies of the region. Thus it is possible to build a solarimetric database and assess photovoltaic potential power generation of each location. On the current study done to Mozambique it was observed that some regions without electricity grid are very adequate to the utilization of solar energy for the direct generation of electricity connected to grid.

A energia solar fotovoltaica é uma alternativa de energia limpa que está se tornando uma importante opção para se utilizar eletricidade em regiões desprovidas de energia elétrica. Um estudo das condições energéticas da região através de consulta às concessionárias de energia elétrica (Eletricidade de Moçambique - EDM no caso de Moçambique) e do Ministério de Energia do Governo, são fontes importantes de dados para se conhecer o cenário energético de cada região. Outra fonte de dados importante para se estimar o potencial de geração de energia solar fotovoltaico sãoos indices de irradiação da região. Estes podemser obtidos através do órgão meteorológico da região (INAM no caso de Moçambique) que forneceesses dados para as principais cidades através de suas estações meteorológicas espalhadas na região. Laboratórios de pesquisa internacionais sãooutra importante fonte de dados solarimétricos, pois utilizam satélites capazes de cobrir todo globo terrestre e os dados obtidos são publicados e permitem, a partir das coordenadas do local, identificar a irradiação solar em diversos locais do mundo. Os dados desses laboratórios podem ser comparados com dados de órgãos oficiais da região. Utilizando o banco de dados solarimétricospode-se calcular o potencial fotovoltaico de geração de energia de cada localização e também definir qual região seria mais propícia a utilização de energiasolar fotovoltaica conectada à rede. / Photovoltaic solar energy is an alternative clean energy that it is becoming an important option to be used in region that it does not have available electricity. A study about energy condition of region contacting local energy company (Electricity of Mozambique EDM in the case of Moçambique) and the ministry of governmental are important resources of data to know the electric power conditions scenery of each region. Another important data resource to assesss the photovoltaic potencial of a region is to access the solarimetric data of region. It should be got from the region meteorological organ (in Mozambique it is INAM) that provides this information for main cities through its meteorological station spread across the region. Research International labs are another important resource of the data. They use satellites that are able to cover the whole terrestrial globe and make it available. These data allow applications through the coordinates of the location, identify the exact solar irradiance at any point (in the case NREL in the USA). Laboratory data should be validated through comparisons with data from the official bodies of the region. Thus it is possible to build a solarimetric database and assess photovoltaic potential power generation of each location. On the current study done to Mozambique it was observed that some regions without electricity grid are very adequate to the utilization of solar energy for the direct generation of electricity connected to grid.

La connaissance du rayonnement solaire, ou irradiation solaire, à la surface de la Terre est d’un grand intérêt dans de nombreux domaines. Cependant le développement de systèmes utilisant l’énergie solaire nécessitent des données sur le rayonnement solaire denses (spatialement et temporellement) et suffisamment précises pour simuler, concevoir, gérer et optimiser le fonctionnement de ces systèmes. L’objectif principal de cette thèse est de concevoir et développer une méthode d'estimation de l'irradiation solaire applicable à la zone intertropicale. Les travaux de la première partie se concentrent sur la recherche d’une solution méthodologique pour estimer le l’irradiation solaire sur la partie Nord du continent Sud-Américain (Plateau des Guyanes) avec une haute résolution spatiale et temporelle et une précision similaire à celle des aux autres méthodes opérationnelles sous d’autres climats. Dans la deuxième partie, nous proposons d’améliorer les estimations d’irradiation solaire obtenues dans la première partie, notamment celles faites en ciel couvert. Le Plateau des Guyanes étant une zone fortement affectée par la ZIC et avec des passages nuageux très fréquents, il nous est apparu nécessaire de compléter les modifications apportées à la méthode originelle en introduisant une modélisation du ciel couvert. Dans la troisième partie, nous proposons de réaliser des cartographies d’indicateurs en utilisant les estimations d’irradiation obtenues avec la méthode Heliosat-2 modifiée. Enfin, nous concluons sur les avancées obtenues en termes de connaissance sur l’irradiation solaire et sur son exploitabilité sur le Plateau des Guyanes / Knowledge of solar radiation, or solar irradiation, at Earth’s surface is of great interest in many fields. However, the development of systems using solar energy need spatially and temporally dense data on solar radiation, sufficiently accurate to simulate, design, generate and optimize the operation of these systems.The main objective of this thesis is to design and develop a method to assess solar irradiation applicable on intertropical regions. The works of the first part focus on the search of a methodological solution to assess solar irradiation on the northern part of the South American continent (Guiana Shield) with a high temporal and spatial resolution and accuracy on the same level of other operational methods under other climates. In the second part, we propose to improve the solar irradiation assessments obtained in the first part, notably those done in cloudy sky. The Guiana Shield being a zone strongly affected by the ITCZ and with recurrent cloudy periods, it appeared necessary to us to complete the changes brought to the original method by introducing a modeling of the cloudy sky. In the third part, we propose to produce maps of indicators by using the assessments of solar irradiation obtained with the modified Heliosat-2 method. Finally, we conclude on the advances obtained in terms of knowledge on solar irradiation and its exploitability on the Guiana Shield.