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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Tendências de temperatura e precipitação e cenários de mudanças climáticas de longo prazo no Nordeste do Brasil e em ilhas oceânicas

LACERDA, Francinete Francis 16 October 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-15T12:33:37Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese__Francis Lacerda_21-03_16.pdf: 3871746 bytes, checksum: ad1b342ab1688e8eb924d0da7d968c22 (MD5) / Made available in DSpace on 2016-07-15T12:33:37Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese__Francis Lacerda_21-03_16.pdf: 3871746 bytes, checksum: ad1b342ab1688e8eb924d0da7d968c22 (MD5) Previous issue date: 2015-10-16 / No Nordeste do Brasil, e particularmente em Pernambuco, a precipitação e a temperatura estão entre as variáveis meteorológicas mais importantes para os estudos das mudanças climáticas, uma vez que sua variabilidade espacial e temporal são características marcantes do clima local. Os objetivos com este trabalho foram:determinar a presença de tendências de longo período da precipitação e da temperatura em Pernambuco, com a utilização de índices de detecção de mudanças climáticas, com base em dados observacionais de estações meteorológicas no continente e em ilhas oceânicas;realizar um estudo de balanço hídrico para o diagnóstico da disponibilidade hídrica e simulações numéricas com modelo atmosférico regional aninhado em cenário global de mudança climática, do modelo climático do Hadley Centre. Este trabalho contém o diagnóstico das alterações climáticas em localidades do estado de Pernambuco e em ilhas no Oceano Atlântico Tropical com dados de séries temporais diárias de temperatura e de precipitação com mais de 40 anos, com cenários futuros de mudanças do clima na região, para o período de 2010 a 2050. Os resultados indicaram tendências de aumento das temperaturas máximas e redução da pluviosidade média anual em todos os postos inspecionados. Em decorrência, constatou-se a tendência à aridificação em localidades do Sertão e do Agreste de Pernambuco. As análises dos dados climáticos em ilhas oceânicas mostraram um pequeno aquecimento em Fernando de Noronha e acentuada tendência de aquecimento e de aridificação em Cabo Verde, semelhantes às tendências de longo prazo detectadas em Araripina, no semiárido de Pernambuco. As tendências de temperatura e precipitação, observadas, são indicativas de que ocorrem processos de aridificação em Pernambuco e Cabo Verde. Os resultados do balanço hídrico e suas projeções indicaram uma diminuição da disponibilidade de água no solo e precipitação total e aumento das taxas de evapotranspiração potencial, em praticamente todas as áreas, ao longo dos anos. As simulações atmosféricas foram consistentes com os dados das estações em relação ao presente aquecimento; os cenários de mudanças climáticas para 2010-2050 indicaram um aumento mais rápido da temperatura máxima diária no Nordeste se comparada às simulações para o passado recente. / In Northeast Brazil, and particularly in Pernambuco, precipitation and temperature are among the most important meteorological variables for studies of climate change, since their spatial and temporal variability characterize the local climate. The aimswith this study were to determine the presence of long-term precipitation and temperature trends in Pernambuco, with the use of climate change detection rates, based on observational data from weather stations on the continent and on oceanic islands and to conduct a water balance study for the diagnosis of water availability and numerical simulations with regional atmospheric model nested in the global scenario of climate change, the Hadley Centre climate model. This work contains the diagnosis of climate change in the State of Pernambuco locations and in the Atlantic Ocean Tropical islands with data daily time temperature series and precipitation over 40 years with future scenarios of climate change in the region, for the period of 2010 to 2050. The results showed increasing trends of maximum temperatures and reduced average annual rainfall at all stations inspected. Also, a tendency to aridificação in the Sertãoand in the Agreste of Pernambuco was detected. The analysis of climate data on oceanic islands showed a small heating in Fernando de Noronha and a marked warming trend and aridificação in Cape Verde, similar to long-term trends detected in Araripina, in the semiarid region of Pernambuco. Trends in temperature and precipitation observed are indicative that aridificação processes in Pernambuco and Cape Verde are on the way. The results of the water balance and its projections indicated a decrease in water availability in the soil and total precipitation and increased evapotranspiration rates, in almost all areas over the years. The weather simulations were consistent with the data of the stations in relation to this warming rate; the climate change scenarios for 2010-2050 indicated a faster increase in the maximum daily temperatures in the Northeast compared to simulations of the recent past.
2

The ecology of the world's smallest tortoise, homopus signatus signatus: effects of rainfall

Loehr, Victor J.T. January 2008 (has links)
Philosophiae Doctor - PhD / Tortoises appear to be successful in arid ecosystems, where they depend on primary production for their predominantly herbivorous diets. The low primary production of arid regions is exacerbated by priodic droughts, so that iteroparous species such as chelonians require mechanisms to overcome resource shortages. The smallest of all tortoises, Homopus signatus signatus, occurs in a dry winter rainfall area in northwestern South Africa that is threatened with aridification due to regional climate change. The overall aim of this study is to understand the ecology of H. s. signatus, particularly in reference to the importance of rainfall.
3

On the Quaternary history of African monsoon : sedimentological and geochemical records from the eastern Mediterranean sea / Évolution de la mousson africaine au cours du Quaternaire : approches sédimentologiques et géochimiques des sédiments terrigènes de la Méditerranée orientale

Zhao, Yulong 29 February 2012 (has links)
Cette thèse vise à restituer l'histoire de la mousson africaine au cours du Quaternaire, et à en déterminer ses influences sur les variations des apports sédimentaires du Nil et des déserts d’Afrique du nord. Deux sites de la Méditerranée orientale ont alors été étudiés (la carotte MD90-964 dans la partie orientale du bassin Levantin et le Site ODP 964 dans la Mer ionienne). Sur la base des analyses de la minéralogie des argiles, de la granulomètrie, de la teneur en carbonate et Corg couplées à des analyses semi-quantitatives d’éléments majeurs et traces à très haute résolution temporelle par XRF Core Scanner, nous avons restitué l’histoire des apports sédimentaires du Nil, des changements de précipitation en l’Afrique du Nord, et des variations des paleo-crues du Nil au cours des 1,75 derniers millions d'années. Le premier enregistrement de Delta(18)O du foraminifère planctonique G. ruber (carotte MD90-964) de l’ensemble du Quaternaire a été obtenu à très haute résolution temporelle pour la Méditerranée orientale. Le site ODP 964 a permis de restituer la dynamique des apports de poussière saharienne à la mer ionienne durant les 1,5 derniers millions d'années. Les résultats indiquent que les changements dans les apports de sédiments transportés par le Nil et par les vents depuis les domaines sahariens sont fortement influencés par les variations de la mousson africaine. Les alternances glaciaires/interglaciaires et les variations climatiques de la transition climatique mi-Pléistocène (MPT), dans une moindre mesure, influencent également / This thesis is devoted to reconstruct the Quaternary history of African monsoon and its influences on suspended loads of the Nile River and dust production in Sahara. The materials used in this study come from two sites (MD90-964 in the eastern Levantine Basin and ODP Site 964 in the Ionian Sea) in the eastern Mediterranean Sea. Based on clay mineralogy, grain sizes, carbonate and Corg contents, and XRF core scanning analyses of Core MD90-964, we have reconstructed history of the Nile suspended discharges, precipitation in North Africa, and Nile paleoflood events during the last 1.75 Ma. On the basis of the planktonic foraminiferal Delta(18)O record of Core MD90-964, we have established for the first time in the eastern Mediterranean Sea a high-resolution planktonic foraminiferal (G. ruber) Delta(18)O record that penetrates the Quaternary period. The ODP Site 964 allows us to establish the variations of Saharan dust inputs to the eastern Mediterranean Sea during the last 1.5 Ma. Our results indicate that both fluvial sediments from the Nile and Saharan eolian dust inputs to the eastern Mediterranean Sea are greatly influenced by the variability of African monsoon. The glacial/interglacial cycles and other orbital-scale climatic events, such as the “Mid-Pleistocene Transition”, can also affect climate changes in North Africa to a minor extent.

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