>Magister Scientiae - MSc / Many hydrocarbon reservoirs are situated in barren sequences that display poor stratigraphic control. Correlation between the wells can become extremely difficult and traditional correlation techniques can prove to be inadequate. Past studies have shown that trace and major element concentrations can be used as a correlation tool. This practice of using geochemical fingerprints to characterize between wells is called Chemostratigraphic analysis. (Pearce et al, 1999) Chemostratigraphy has been recognized as a very important correlation technique as it can be used for rocks of any age, in any geological setting as well as sequences that are traditionally defined as barren. Chemostratigraphic analyses can be used as a means of getting rid of ambiguities within data produced by traditional correlation methods such as Biostratigraphy, Lithostratigraphy and Geophysical Logging. In areas where stratigraphic data is not available it can be used to construct correlation frameworks for the sequences found in the area. The motivation behind this study is that the research is not only worthy of academic investigation, but can also provide the industry with new insights into areas that were previously misunderstood because traditional correlation methods were not adequate. The study area, the Orange basin, is located offshore South Africa and is largely underexplored. The basin, that hosts two gas field namely the Ibhubesi and the Kudu gas fields, has large potential but in the past has not been given due attention with only 34 wells being drilled in the area. The Orange basin has recently been the topic of investigation because of the belief that it may be hosts to more hydrocarbons. This study will utilise Chemostratigraphy to attempt to provide geological information on this relatively under-explored basin. The aim of this research study is to produce a chemostratigraphic framework -scheme for the Orange Basin in order to facilitate reservoir scale interwell correlation. The Objectives of this research study will be to identify chemostratigraphic units or indices, to prove the adequate use of chemostratigraphy as an independent correlation technique and to integrate the chemostratigraphy and petrophysical characteristics of the four wells to facilitate lithological identification. Element distribution Analysis was done on the data. This brought to the fore. the dominance of Si02 across the samples for the four wells. Ah03 concentrations were relatively high across the wells and were indicative of the clay rich nature of the samples. This also indicated that the samples were relatively immature. Principal Component Analysis (PCA) plots were constructed for the purpose of identifying diametrical relationships between the elements or element clusters. These diametric relationships were in turn used to calculate the geochemical indices. The relative positions of the elements on the PCA plot highlighted the presence of alternating units of sandstone, feldspathic sandstone, calcareous clays and non calcareous clays within the samples. The PCA plots displayed diametric relationships between Si02 and the carbonate mineral clusters, Si02 and the clay mineral clusters, Nd and V, Nb nad Ni, Zr and Co, Nb and Zn. Si02 and Co, Y and Pb, Zr and Sr, and lastly Nb and Ra / Downhole plots were constructed to illustrate recognizable trends in the PCA plot and to relate this to the occurrence of various lithologies in the wells. Based on the element distribution patterns, PCA plots and Major and Trace element downhole profiles geochemical indices were calculated. They are grouped into three clusters, ratios indicative of the presence of clean sandstones (High Si02/Ah03, Si02/Co, Zr/Co, Zr/Sr, YlPb and low Nd/V values); ratios indicative of the presence of clays (Low Si02/Ah03, Fe203/Ah03, Si02/Co, Zr/Co, YlPb and high Rb/Zn values); thirdly those indicative of the presence of feldspathic sandstones (High Na201K20) and lastly those indicative of the presence of carbonates (low Zr/Sr). Using the geochemical Indices six units were identified in Well A_AI, nine in A-II and 8 iin Well A-UI and A-LI. Four units (A-D) were found to correlate across the wells. I Well log interpretation for the Wells A-AI, A-II, A-Lland A-UI started with a general overview of the log responses. The log responses for the four wells highlighted the presence of sandstones, argillaceous sandstones, shales and shale components. Geophysical units were identified using the logs responses. Six units were identified in Well A-AI, nine in Well A-II and eight in Wells A-LI and A-UI. These units coincide with the units identified using Chemostratigraphic analysis. Neutron - Density cross plots were constructed for each unit across the four wells. The plotting of the points on the Neutron - Density cross plots for the wells A-AI, A-II, A-LI and A-UI indicated the presence of sandstones, shales or greywackes and either limestones and dolomites but from the geochemistry it is known that neither limestone nor dolomite is present in the wells and it was thus inferred that the points plotting between the limestone and dolomite lithology curves indicated the presence of calcareous shales. M-N plots were constructed for each unit. The patterns exhibited by the points on the M-N plots for the wells was indicative of the presence calcareous clays, sandstones, greywacke and shales. The Chemostratigraphic and Petrophysical results produced accurate and comparable results, however, the Chemostratigraphic analysis provided finer details regarding the lithology of the units. Based on the well log responses no distinction could be made between highly feldspathic sandstone, arkosic and argillaceous sandstone, while these distinctions were possible when analyzing the samples using Chemostratigraphy. The geochemistry was capable of providing signatures in areas where the wireline tools malfunctioned. The logs, on the other hand, sheds light on properties such as porosity and permeability of the rocks which cannot be obtained accurately from the geochemistry. When comparing the correlation capabilities of these two techniques, the one based on geochemical signatures and the other based on the responses obtained from wireline tools, it is important to acknowledge that both these techniques has strengths and weaknesses. The best of both these techniques can only be fully utilised when either technique is used in conjunction with other techniques. With respect to the Orange Basin, located offshore South Africa, it can be concluded that the dominant lithologies in the basin are sandstones, argillaceous sandstones, shales, feldspathic and arkosic sandstones and clays. In terms of petroleum prospectivity the sandstones in Wells A-AI, A-II, A-UI and A-LI could possibly be considered to be reservoirs and the shales could be considered to be seals or source rocks, depending on the organic matter content. On the down side, the sandstones display relatively poor permeabilities and the porosities are variable. The density logs indicate that the sandstones are highly compacted and that could be an indication of poor porosities but more research needs to be done. Another factor highlighted from the research is the presence of alternating lithologies. This means that the reservoirs are compartmentalised and that the area has a high degree of heterogeneity.

Este trabalho teve como objetivo investigar processos de interação ar-mar na porção leste da América do Sul e Oceano Atlântico adjacente ao longo do Holoceno (últimos 12.000 anos). Para isso, os efeitos de forçantes naturais sobre a variabilidade climática foram investigados em três escalas temporais: (i) milenar-centenária: efeitos de pulsos de degelo no Oceano Atlântico, e de variações nas forçantes solar e orbital sobre o modo dipolar subtropical do Atlântico sul e consequências sobre a precipitação, durante o Holoceno; (ii) cenário médio: efeitos de diferenças na forçante orbital em relação ao clima presente sobre a precipitação média no continente, durante o Holoceno médio (6.000 anos atrás), por meio de uma compilação de dados paleoclimáticos inédita para esse período, e comparação com resultados de simulações numéricas; (iii) multidecadal: efeitos de variações na forçante vulcânica ao longo do último milênio (850 a 1850 da Era Comum) sobre a variabilidade do modo equatorial do Atlântico e consequências sobre a precipitação na América do Sul. Os resultados mostraram efeitos dos eventos de rápido resfriamento do Hemisfério norte na variabilidade do modo dipolar subtropical do Atlântico sul, com consequências principalmente sobre a precipitação do Nordeste do Brasil. O cenário médio para o Holoceno médio apontou déficit hídrico na porção leste da América do Sul durante esse período, relacionado com menor quantidade de insolação de verão recebida pelo Hemisfério sul. A dificuldade na coleta de testemunhos marinhos foi identificada como um dos principais limitantes em estudos paleoclimáticos. O vulcanismo explosivo observado no último milênio resfriou a região tropical no ano da erupção, e enfraqueceu a relação entre a precipitação na porção leste da América do Sul e o modo equatorial do Atlântico. Finalmente, a presente tese demonstrou, por meio de comparações dados-modelo, a importância do Oceano Atlântico no regimes de chuva da América do Sul em diversas escalas temporais para climas onde a forçante antropogênica era pouco significativa. 195 pp. / This work investigates the air-sea interaction processes in eastern South America and the adjacent Atlantic Ocean for the Holocene (past 12,000 years). The effects of the natural forcings on climate variability were investigated in three time-scales: (i) millennial-to-centennial: effects of Atlantic meltwater pulses and changes in the solar and orbital forcings on the South Atlantic subtropical dipole, and rainfall impacts during the Holocene; (ii) mid-Holocene scenario: effects of changes in the orbital forcing, in comparison to the present-day conditions, on mean precipitation over the continent, during the mid-Holocene (6,000 years ago). This was achieved through an unpublished multiproxy compilation and comparison with numerical experiments; (iii) multidecadal: effects of changes in the volcanic forcing along the past millennium (850 to 1850 Common Era) on the variability of the Atlantic equatorial mode and consequences on precipitation over South America. Results show effects of the Northern Hemisphere cooling events on the variability of the South Atlantic subtropical dipole, with impacts mainly over Northeastern Brazil\'s rainfall. The mid-Holocene scenario results indicate a water deficit in eastern South America during this period related to a decrease in Southern Hemisphere summer insolation. The difficulty in marine cores sampling is identified as one of the main problems in current paleoclimate studies. The explosive volcanism observed during the past millennium cooled the tropical regions at the year of the volcanic eruption, and weakened the relation between the precipitation in eastern South America and the Atlantic equatorial mode. This thesis shows through data-model approaches the importance of the Atlantic Ocean on South America precipitation regimes in the climate timescales where the anthropogenic forcing was not so relevant. 195 pp.

Este trabalho teve como objetivo investigar processos de interação ar-mar na porção leste da América do Sul e Oceano Atlântico adjacente ao longo do Holoceno (últimos 12.000 anos). Para isso, os efeitos de forçantes naturais sobre a variabilidade climática foram investigados em três escalas temporais: (i) milenar-centenária: efeitos de pulsos de degelo no Oceano Atlântico, e de variações nas forçantes solar e orbital sobre o modo dipolar subtropical do Atlântico sul e consequências sobre a precipitação, durante o Holoceno; (ii) cenário médio: efeitos de diferenças na forçante orbital em relação ao clima presente sobre a precipitação média no continente, durante o Holoceno médio (6.000 anos atrás), por meio de uma compilação de dados paleoclimáticos inédita para esse período, e comparação com resultados de simulações numéricas; (iii) multidecadal: efeitos de variações na forçante vulcânica ao longo do último milênio (850 a 1850 da Era Comum) sobre a variabilidade do modo equatorial do Atlântico e consequências sobre a precipitação na América do Sul. Os resultados mostraram efeitos dos eventos de rápido resfriamento do Hemisfério norte na variabilidade do modo dipolar subtropical do Atlântico sul, com consequências principalmente sobre a precipitação do Nordeste do Brasil. O cenário médio para o Holoceno médio apontou déficit hídrico na porção leste da América do Sul durante esse período, relacionado com menor quantidade de insolação de verão recebida pelo Hemisfério sul. A dificuldade na coleta de testemunhos marinhos foi identificada como um dos principais limitantes em estudos paleoclimáticos. O vulcanismo explosivo observado no último milênio resfriou a região tropical no ano da erupção, e enfraqueceu a relação entre a precipitação na porção leste da América do Sul e o modo equatorial do Atlântico. Finalmente, a presente tese demonstrou, por meio de comparações dados-modelo, a importância do Oceano Atlântico no regimes de chuva da América do Sul em diversas escalas temporais para climas onde a forçante antropogênica era pouco significativa. 195 pp. / This work investigates the air-sea interaction processes in eastern South America and the adjacent Atlantic Ocean for the Holocene (past 12,000 years). The effects of the natural forcings on climate variability were investigated in three time-scales: (i) millennial-to-centennial: effects of Atlantic meltwater pulses and changes in the solar and orbital forcings on the South Atlantic subtropical dipole, and rainfall impacts during the Holocene; (ii) mid-Holocene scenario: effects of changes in the orbital forcing, in comparison to the present-day conditions, on mean precipitation over the continent, during the mid-Holocene (6,000 years ago). This was achieved through an unpublished multiproxy compilation and comparison with numerical experiments; (iii) multidecadal: effects of changes in the volcanic forcing along the past millennium (850 to 1850 Common Era) on the variability of the Atlantic equatorial mode and consequences on precipitation over South America. Results show effects of the Northern Hemisphere cooling events on the variability of the South Atlantic subtropical dipole, with impacts mainly over Northeastern Brazil\'s rainfall. The mid-Holocene scenario results indicate a water deficit in eastern South America during this period related to a decrease in Southern Hemisphere summer insolation. The difficulty in marine cores sampling is identified as one of the main problems in current paleoclimate studies. The explosive volcanism observed during the past millennium cooled the tropical regions at the year of the volcanic eruption, and weakened the relation between the precipitation in eastern South America and the Atlantic equatorial mode. This thesis shows through data-model approaches the importance of the Atlantic Ocean on South America precipitation regimes in the climate timescales where the anthropogenic forcing was not so relevant. 195 pp.

Submitted by CAMILA CRISTINA RIBEIRO LUIS null (camila.luis@yahoo.com.br) on 2018-03-26T15:44:43Z No. of bitstreams: 1 Tese Camila.pdf: 4455685 bytes, checksum: 49398391cfc7016b7cdf100c729e65e1 (MD5) / Approved for entry into archive by Satie Tagara (satie@marilia.unesp.br) on 2018-03-26T19:18:15Z (GMT) No. of bitstreams: 1 luis_ccr_dr_mar.pdf: 4455685 bytes, checksum: 49398391cfc7016b7cdf100c729e65e1 (MD5) / Made available in DSpace on 2018-03-26T19:18:15Z (GMT). No. of bitstreams: 1 luis_ccr_dr_mar.pdf: 4455685 bytes, checksum: 49398391cfc7016b7cdf100c729e65e1 (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O trabalho tem por objetivo analisar a dimensão do Atlântico Sul na política externa brasileira, considerando como referência teórica os conceitos e práticas da política exterior brasileira, bem como a análise do conceito de Poder Marítimo, na perspectiva de realização de uma Estratégia Marítima. Assim, analisamos o processo de formulação de políticas voltadas para o mar, que ganharam espaço na agenda brasileira a partir da intensificação das discussões internacionais em torno do aproveitamento do espaço marítimo, das quais o Brasil procurou participar ativamente. A partir dessa análise inicial, as resultantes do processo interno foram confrontadas com o contexto geopolítico do Atlântico Sul, em paralelo à presença de outros atores nessa área marítima. Tal embate analítico aponta para o dualismo entre um “Atlântico Sul regional”, consubstanciado na Zona de Paz e Cooperação do Atlântico Sul, e um “Atlântico Sul global”, marcado pelo contexto da globalização e das novas ameaças, traduzido em diversas iniciativas, que integram a área marítima sul-atlântica à política global. Assim, a política externa brasileira no Atlântico Sul projeta-se em uma área marítima onde coexistem e se sobrepõem estratégias multifacetadas, contrapondo atores globais com ambições em escala mundial e atores regionais, em que prevalece a influência direta do eixo estratégico formado por potências navais do Atlântico Norte. / The objective of this paper is to analyze the South Atlantic dimension in Brazilian foreign policy, considering as theoretical reference the concepts and practices of Brazilian foreign policy, as well as the analysis of the concept of Seapower and Maritime Strategy. From this perspective, the paper analyzes the process of formulating policies concerned to the sea, which have gained space in the Brazilian agenda as a result of the intensification of international discussions about the use of maritime space, that Brazil has actively sought to participate in. From this initial analysis, those resulting from the internal process were confronted with the geopolitical context of the South Atlantic, in parallel with the presence of other actors present in this maritime area. This analytical clash points to the dualism between a “regional South Atlantic”, embodied in the South Atlantic Peace and Cooperation Zone, and a “global South Atlantic”, marked by the context of globalization, new threats, and differentiated initiatives that integrate the South Atlantic in the global politics. Thus, the Brazilian foreign policy in the South Atlantic is projected in a maritime area where multi-faceted maritime strategies coexist and overlap, opposing global players with global ambitions and regional actors, in which prevails the influence of the great powers of North Atlantic. / El trabajo tiene por objetivo analizar la dimensión del Atlántico Sur en la política exterior brasileña, considerando como referencia teórica los conceptos y prácticas de la política exterior brasileña, así como el análisis del concepto de Poder Marítimo, en la perspectiva de realización de una Estrategia Marítima. Así, el trabajo analiza el proceso de formulación de políticas orientadas al mar, que ganaron espacio en la agenda brasileña a partir de la intensificación de las discusiones internacionales en torno al aprovechamiento del espacio marítimo, de las cuales Brasil buscó participar activamente. A partir de ese análisis inicial, las resultantes del proceso interno son confrontadas al contexto geopolítico del Atlántico Sur, en paralelo a la presencia de otros actores presentes en esa área marítima. Tal embate analítico apunta al dualismo entre un “Atlántico sur regional”, consubstanciado en la Zona de Paz y Cooperación del Atlántico Sur, y un “Atlántico Sur global”, marcado por el contexto de la globalización y de las nuevas amenazas, traducido en iniciativas diferenciadas, que integran el área marítima sur-atlántica en la política global. La política exterior brasileña en el Atlántico Sur se proyecta en un área marítima donde coexisten y se superponen estrategias marítimas múltiples, contraponiendo actores globales con ambiciones a escala mundial y actores regionales, en que prevalece la influencia directa del eje estratégico formado por potencias navales del Atlántico Norte.

Nos estudos de populações pesqueiras é comum o uso de modelos hidrodinâmicos acoplados a modelos biológicos e, um tipo de modelo merece destaque: o baseado no indivíduo (IBM). A Plataforma Continental do Atlântico Sudoeste comporta uma importante atividade pesqueira e, a influência da circulação na distribuição de ovos/larvas nessa região é pouco entendida. Estudos anteriores sugerem que o transporte de Ekman em direção à costa e o deságue de água fluvial impedem a perda de ovos e larvas da área costeira. Este trabalho apresenta resultados de um estudo englobando os padrões de circulação e de transporte de larvas nessa área, realizado através do desenvolvimento de um IBM para os estágios iniciais da Engraulis anchoita e o acoplamento deste a dois campos de velocidade superficial: a de Ekman, e a saída de um modelo hidrodinâmico 3D. Os resultados mostram que somente a deriva de Ekman não é suficiente para explicar o padrão de retenção larval observado na região. Os valores de retenção encontrados com a utilização da saída do modelo estão próximos aos observados. Maiores concentrações larvais foram obtidas no outono/inverno e menores na primavera/verão. Estes resultados estão diretamente relacionados à combinação dos efeitos dos padrões de vento da área com a influência das Correntes do Brasil e das Malvinas e do deságue continental na circulação sobre a plataforma. / Recruitment of pelagic fishes is the net result a series of continuous events in their life cycle. Most of the variability in natural mortality is thought to occur during the early stages of development and is related to environmental factors. The use of coupled physical-biological modeling in the study of fisheries populations is very common and a particular type of model deserves special mention: the Individual Based Model (IBM). The Atlantic Southwestern Continental Shelf is one of the most productive fishing sites in the Western South Atlantic, but the processes involving the circulation in this area and its influence on eggs/larvae transport and retention are still poorly understood. Recent studies describe the spawning activity of anchovy and its relationship to oceanographic processes and suggest that predominant onshore Ekman transport, during the austral winter/spring, keeps the eggs and larvae in coastal areas. According to these studies, the river runoff contributes to the formation of a retention zone for planktonic organisms over the area. This work presents results of a study that considers both the circulation pattern and larval transport, throught the development of an IBM for the early stages of anchovy Engraulis anchoita. The model is coupled to two surface velocity fields: the Ekman drift, and the output of a 3D hydrographic model. The results show that just Ekman surface velocities are not able to explain the larval dispersion observed in this region. Retention values obtained with the model output are much closer to observed values. Autumn and winter seasons present the highest values of retention. These results are due to the combined effect of the wind patterns registered in the area with the influence of the river runoff and the Brazil-Malvinas shelf circulation.

Oceanic Gyres are the most conspicuous features in the Earth\'s ocean. They are ubiquitous to each basin and hemisphere. In the Atlantic Ocean, there is an uncanny symmetry between the North and South Atlantic Subtropical Gyres. Focusing on their poleward limits, we can think of them as virtually perfect analogues. However, while the North Atlantic Current has been extensively studied, the South Atlantic Current (SAC) still has been very little investigated and its knowledge presents crucial gaps on understanding it ocean\'s mesoscale variability and climate. Very little studies attempted so far to describe the SAC characteristics in terms of water mass properties and volume transports. In addition, there is the presence of recently described Saint Helen Current (StHC), which can be considered as the South Atlantic analogue of the Azores Current. The StHC has its formation tied with the Brazil Current (BC) retroflection. The SAC, on the other hand, is originated at the Brazil-Malvinas Confluence (BMC), and flows crossing zonally the Atlantic Basin. However, the presence of the northern branch of Antarctic Circumpolar Current (ACCn) (without an analogue in the northern hemisphere) brought a few additional challenges to studying the SAC. The ACCn can be thought as the Malvinas Current (MC) Extension, which exits the BMC region via the southern flank of the Zapíola Rise. In this work, we revisit the descriptive oceanography of the SAC system with newly developed climatologies (WOA13 and ARMOR3D) and seek to unravel the pattern associated with the current in the Southern limb of the region. Recent literature mentions that there is an important interplay between this three zonal jets as the cross the South Atlantic. However, only kinematics arguments were used to pinpoint this interplay so far. Hence, we opted to employ a statistical correlation method involving temperature, salinity and density vertical profiles (and consequently, T-S curves as well). We also computed volume transport values for the whole zonal domain across the South Atlantic Subtropical Gyre southern limb. In particular, at the longitude that it reaches the Mid-Atlantic Ridge, the major portion of the SAC veers south and merge almost completely with the ACCn. Its smaller northern the StHC. Near the eastern ocean border of the South Atlantic Ocean, the SAC-ACCn as well as a portion of the StHC traverse into the Indian Ocean. The combined analysis of geostrophic streamfunction fields and the temperature-density correlation diagrams do not show sufficient evidence for the StHC being an independent current, and not a branch of the SAC. Since there is also no study regarding the dynamics of the SAC we also constructed a linear QG instability model aiming to evaluate the current system mesoscale activity. We then analyzed the mesoscale activity of the SAC, and discovered that SAC is unstable throughout the whole path domain towards Africa. This instabilities, however, are found to be not as vigorous as the ACC. We also identify a shift in mesoscale vorticity wave regime as the SAC crosses the Mid-Atlantic Ridge. We found it to be less unstable than at the western side. We, however, could not identify the type of instabilities associated with the current. Therefore, we propose as sequential future work to further pursue investigation on the mesoscale dynamics of the ACCn-SAC-StHC system. / Os Giros Oceânicos são os aspectos mais notáveis dos oceano. Eles são ubíquos em todos os hemisférios e bacias oceânicas. No Atlântico, por exemplo, existe uma clara simetria entre os giros subtropicais do Atlântico norte e sul. Nos seus limites mais polar, podemos pensar neles como análogos perfeitos. Entretanto, enquanto a Corrente do Atlântico Norte foi extensamente estudado, a Corrente do Atlântico Sul ainda tem sido muito pouco investigada deixando lacunas cruciais no conhecimento no entendimento do clima e variabilidade de mesoscala nos oceanos. Pouquíssimos estudos foram realizados até agora a fim de descrever a CAS e suas características nos tópicos relacionados às propriedades das massas de água transporte de voluma. Ademais, há a presença de um corrente recentemente descrita, cunhada de Corrente de Santa Helena (CStH) que pode considerada, tal qual a Corrente do Atlântico Sul, uma análoga da Corrente dos Açores. A CStH possui sua formação atrelada à Corrente do Brasil (CB). A CAS, por sua vez, origina-se na confluência Brasil-Malvinas e escoa atravessando zonalmente a bacia do Atlântico. Entretanto, a presença do ramo norte da Corrente Circumpolar Antártica (CCAn) (sem um análogo no hemisfério norte) trouxe desafios adicionais ao estudo da CAS. A CCAn pode ser pensada como uma extensão da Corrente das Malvinas (CM), a qual sai da região da confluência via o flanco sul da Elevação de Zapiola. Nesse trabalho, revisitamo a oceanografia descritiva do sistema CAS com novas climatologias desenvolvidas (WOA13 e ARMOR3D) e procuramos desvendar o padrão associado à corrente no membro sul da região. Estudos recentes apontam uma importante interação entre os três jatos zonais enquanto atravessam o Atlântico Sul. Somente argumentos cinemáticos, entretanto, foram utilizados para identificar essa interação. Consequentemente, optamos em empregar um método de correlação estatística envolvendo perfis verticais de temperatura, salinidade e densidade(e, logo, curvas T-S). Nós também calculamos o transporte de volume para todo o domínio zonal através do ramo sul do Giro Subtropical do Atlântico Norte. Em particular, na longitude que alcança a Cadeia Meso-Atlântica, a maior porção da CAS desvia-se para o sul e dilui-se quanse que por completo à CCAn. Próxima à borda este do Oceano Atlântico Sul, tanto a CAS-CCAn como uma parte da CStH atravessam em direção ao Oceano Índico. A análise combinada dos campos de função de corrente geostróficos e pelos diagramas de correlação de temperatura-densidade não mostra evidências suficientes para que a CStH seja considerada uma corrente independente e não um ramo da CAS. Além disso, já que não há estudos relacionados a dinâmica da CAS, nós tambémconstruímos um modelo de instabilidade QG a fim de avaliar a atividade de mesoscala do sistema de correntes. Analisamos essa atividade da CAS e descobrimos que ela é instável durante todo o seu percurso em direção à África. Essas instabilidades, entretanto, não são tão vigorosas quanto aquelas da CCA. Também identidicamos mudanças no regime de ondas das vorticidades de mesoscala no cruzamento da CAS com a cadeia meso-oceânica. Descobrimos que a corrente é menos instável ao lado leste da cadeia. Não podemos, contudo, identificar os tipos de instabilidades associada à corrente. Por conseguinte, propomos trabalhos futuros que irão auxiliar à investigação da dinâmica de mesoscala do sistema CCAn-CAS-CstH.

Made available in DSpace on 2016-04-25T20:22:24Z (GMT). No. of bitstreams: 1 Edson Tomaz de Aquino.pdf: 598711 bytes, checksum: ef991423cd49a8bc280bd6d9542e97a2 (MD5) Previous issue date: 2008-06-20 / The main purpose of this work is to show the growing importance of South Atlantic Ocean to Brazil s foreign policy and security issues, from the seventies to 21st century. The oil crises in the early seventies changed brazilian perception about its maritime frontier. The enlargement of territorial sea to 200 miles and a diplomatic approach to Africa were strategic to assure Brazilian interests in the South Atlantic. The central role of Brazil to build the Zone of Peace and Cooperation of the South Atlantic stresses the choice to the multilateralism and the international law. This choice results from regional and hemispheric context. In the early 21st century, the international system allows Brazil to drawn a military capability towards its maritime frontier. Economic resources as great stocks of oil could turn the South Atlantic a vulnerable zone to Brazilian interests. Idealism and Realism on foreign politics and defense issues tend to combine themselves on Brazil s projection at South Atlantic / O objetivo principal deste trabalho consiste em demonstrar a crescente importância do Atlântico Sul na política externa e nos assuntos de defesa do Brasil, desde a década de 70 até o limiar do século XXI. A crise do petróleo, no início da década de 70 transformou a percepção do Brasil sobre sua fronteira marítima. O alargamento do mar territorial para 200 milhas e a aproximação diplomática da África foram estratégicos para assegurar os interesses do Brasil no Atlântico Sul. O papel central do Brasil em construir a Zona de Paz e Cooperação do Atlântico Sul reforçou a escolha pelo multilateralismo e pelo direito internacional. Essa escolha foi decorrente do contexto regional e hemisférico. No início do século XXI, o Brasil percebe possibilidades de projetar uma capacidade militar para defender sua fronteira marítima. Recursos econômicos, como grandes reservas de petróleo, podem tornar o Atlântico Sul uma área vulnerável para os interesses brasileiros. No entanto, idealismo e realismo em política externa e defesa tendem a combinar-se na projeção do Brasil no Atlântico Sul

Nos estudos de populações pesqueiras é comum o uso de modelos hidrodinâmicos acoplados a modelos biológicos e, um tipo de modelo merece destaque: o baseado no indivíduo (IBM). A Plataforma Continental do Atlântico Sudoeste comporta uma importante atividade pesqueira e, a influência da circulação na distribuição de ovos/larvas nessa região é pouco entendida. Estudos anteriores sugerem que o transporte de Ekman em direção à costa e o deságue de água fluvial impedem a perda de ovos e larvas da área costeira. Este trabalho apresenta resultados de um estudo englobando os padrões de circulação e de transporte de larvas nessa área, realizado através do desenvolvimento de um IBM para os estágios iniciais da Engraulis anchoita e o acoplamento deste a dois campos de velocidade superficial: a de Ekman, e a saída de um modelo hidrodinâmico 3D. Os resultados mostram que somente a deriva de Ekman não é suficiente para explicar o padrão de retenção larval observado na região. Os valores de retenção encontrados com a utilização da saída do modelo estão próximos aos observados. Maiores concentrações larvais foram obtidas no outono/inverno e menores na primavera/verão. Estes resultados estão diretamente relacionados à combinação dos efeitos dos padrões de vento da área com a influência das Correntes do Brasil e das Malvinas e do deságue continental na circulação sobre a plataforma. / Recruitment of pelagic fishes is the net result a series of continuous events in their life cycle. Most of the variability in natural mortality is thought to occur during the early stages of development and is related to environmental factors. The use of coupled physical-biological modeling in the study of fisheries populations is very common and a particular type of model deserves special mention: the Individual Based Model (IBM). The Atlantic Southwestern Continental Shelf is one of the most productive fishing sites in the Western South Atlantic, but the processes involving the circulation in this area and its influence on eggs/larvae transport and retention are still poorly understood. Recent studies describe the spawning activity of anchovy and its relationship to oceanographic processes and suggest that predominant onshore Ekman transport, during the austral winter/spring, keeps the eggs and larvae in coastal areas. According to these studies, the river runoff contributes to the formation of a retention zone for planktonic organisms over the area. This work presents results of a study that considers both the circulation pattern and larval transport, throught the development of an IBM for the early stages of anchovy Engraulis anchoita. The model is coupled to two surface velocity fields: the Ekman drift, and the output of a 3D hydrographic model. The results show that just Ekman surface velocities are not able to explain the larval dispersion observed in this region. Retention values obtained with the model output are much closer to observed values. Autumn and winter seasons present the highest values of retention. These results are due to the combined effect of the wind patterns registered in the area with the influence of the river runoff and the Brazil-Malvinas shelf circulation.

Made available in DSpace on 2016-04-26T14:57:13Z (GMT). No. of bitstreams: 1 Edson Tomaz de Aquino.pdf: 598711 bytes, checksum: ef991423cd49a8bc280bd6d9542e97a2 (MD5) Previous issue date: 2008-06-20 / The main purpose of this work is to show the growing importance of South Atlantic Ocean to Brazil s foreign policy and security issues, from the seventies to 21st century. The oil crises in the early seventies changed brazilian perception about its maritime frontier. The enlargement of territorial sea to 200 miles and a diplomatic approach to Africa were strategic to assure Brazilian interests in the South Atlantic. The central role of Brazil to build the Zone of Peace and Cooperation of the South Atlantic stresses the choice to the multilateralism and the international law. This choice results from regional and hemispheric context. In the early 21st century, the international system allows Brazil to drawn a military capability towards its maritime frontier. Economic resources as great stocks of oil could turn the South Atlantic a vulnerable zone to Brazilian interests. Idealism and Realism on foreign politics and defense issues tend to combine themselves on Brazil s projection at South Atlantic / O objetivo principal deste trabalho consiste em demonstrar a crescente importância do Atlântico Sul na política externa e nos assuntos de defesa do Brasil, desde a década de 70 até o limiar do século XXI. A crise do petróleo, no início da década de 70 transformou a percepção do Brasil sobre sua fronteira marítima. O alargamento do mar territorial para 200 milhas e a aproximação diplomática da África foram estratégicos para assegurar os interesses do Brasil no Atlântico Sul. O papel central do Brasil em construir a Zona de Paz e Cooperação do Atlântico Sul reforçou a escolha pelo multilateralismo e pelo direito internacional. Essa escolha foi decorrente do contexto regional e hemisférico. No início do século XXI, o Brasil percebe possibilidades de projetar uma capacidade militar para defender sua fronteira marítima. Recursos econômicos, como grandes reservas de petróleo, podem tornar o Atlântico Sul uma área vulnerável para os interesses brasileiros. No entanto, idealismo e realismo em política externa e defesa tendem a combinar-se na projeção do Brasil no Atlântico Sul

The Late Cretaceous–early Paleogene is the most recent period of Earth history with a dynamic carbon cycle that experienced sustained global greenhouse warmth and can offer a valuable insight into our anthropogenically-warmer future world. Yet, knowledge of ambient climate conditions and evolution of the carbon cycle at this time, along with their relation to forcing mechanisms, are still poorly constrained. In this thesis, I examine marine sediments recovered from the South Atlantic Walvis Ridge (ODP Site 1262) and Indian Ocean Ninetyeast Ridge (IODP Site U1443 and ODP Site 758), to shed new light on the evolution of the climate and carbon cycle from the Late Maastrichtian through to the Early Eocene (~67.10–52.35 Ma). The overarching aims of this thesis are: 1) to identify the long-term trends and principle forcing mechanisms driving the climate and carbon cycle during this time period, through construction of 14.75 million-year-long, orbital-resolution (~1.5–4 kyr), stratigraphically complete, benthic stable carbon (δ13Cbenthic) and oxygen (δ18Obenthic) isotope records; 2) to investigate in more detail the climatic and carbon-cycle perturbations of the Early–Middle Paleocene (e.g., the Dan-C2 event, Latest Danian Event and the Danian/Selandian Transition Event) and place these in their proper (orbital) temporal context; 3) to investigate the Late Maastrichtian warming event and its relationship to the eruption of the Deccan Traps Large Igneous Province, as well as its role (if any) in the subsequent Cretaceous/Paleogene (K/Pg) mass extinction; 4) to provide the first orbital-resolution estimates of temperature and carbonate chemistry variability from the low latitude Indian Ocean spanning the Late Paleocene–Early Eocene, through analysis of trace element and stable isotope data from multiple foraminiferal species. Taken together, the results presented in this thesis provide a critical new insight into the dynamic evolution of the climate and carbon cycle during the greenhouse world of the early Paleogene, and shed light on the potential forcing mechanisms driving the climate and carbon cycle during this time.