Este trabalho tem por objetivo descrever a Anomalia Magnética do Atlântico Sul (SAMA) utilizando os modelos para o período histórico (1600–1890) e também os modelos para o último século (DGRF e IGRF). Como a SAMA apresenta características de baixa intensidade do campo total e coincide com a região de intenso fluxo de partículas cósmicas, muitos problemas com objetos que orbitam a Terra (por exemplo, satélites) são detectados nessa região. São descritos os efeitos provocados pela SAMA em fenômenos espaciais. Através da análise dos modelos na forma de mapas, foram extraídos os dados de mínima intensidade para o centro da SAMA e a posição destes pontos, possibilitando conhecer a trajetória e as taxas de deriva. Os modelos foram testados na interface manto-núcleo através da componente vertical, para encontrar correlação com anomalias em superfície. Os resultados mostraram deriva para Oeste constante e variações em latitude. Foi observado que as intensidades acompanham a diminuição de todo o campo, embora a SAMA apresente caráter predominantemente não-dipolar, evidenciada pela razão entre o campo não-dipolar e o campo total no Atlântico Sul. A comparação de intensidades da SAMA com as medidas de intensidade realizadas pelos observatórios mostrou que a influência da SAMA aparece na forma de sobreposição ou amplificação de fenômenos com menor comprimento de onda, como os impulsos de variação secular (jerks geomagnéticos). A continuação para baixo dos modelos se mostrou satisfatória quando comparada com o método de inversão estocástica. A comparação da SAMA com outras anomalias em superfície mostrou independência na trajetória, porém, quando comparadas com os lóbulos principais na interface manto-núcleo, indicam que estas anomalias possam estar interligadas. Os lóbulos do núcleo foram interpretados com base nos mecanismos de geração, sugerindo que a SAMA possa ser originada através de movimentos combinados entre duas colunas de convecção e regiões de fluxo reverso no núcleo externo. / The object of this dissertation is to describe the South Atlantic Magnetic Anomaly (SAMA) using geomagnetic models for the historical period from 1600 to 1890 and also the IGRF and DGRF models for the past century. Since the SAMA presents low intensities of the total geomagnetic field that correspond to a region of intense cosmic ray particle flux, many problems with objects that orbit along this region (eg. Satelites) have been detected. The SAMA effects on space vehicles are described. The field models led to the definition of the SAMA center as the locus of minimum total field intensity and how the anomaly drifted and varied in intensity for the past four centuries. The vertical component at the Core Mantle Boundary (CMB) was used to find correlations with anomalies at the surface the Earth surface. Results have shown a rather constant westward drift and also latitude variations. It was observed that intensities follow the general decrease of the total field although the SAMA displays a predominantly non-dipolar character that is evident in the non-dipolar/total field ratios for the South Atlantic. The comparison of geomagnetic measurements by nearby Southamerican Observatories show that the SAMA influence appears as a superposition or amplification of lower wavelength phenomena such as the secular variation impulses (jerks). A downward continuation of the models was found satisfactory when compared to the stochastic inversion method. The comparison of the SAMA with other surface anomalies showed a rather independent behavior however, a comparison with the main radial component lobes at the CMB showed that all these anomalies may be interconnected. The nucleus lobes have been interpreted under the light of field generation processes, suggesting that the SAMA may originate from the combined motion of two convection columns and reverse flux regions in the outer core.

O objetivo deste trabalho é apresentar a teoria fundamental da análise de massas de água baseada nas características temperatura e salinidade, e a sua aplicação, em grande escala, às águas que circulam na troposfera oceânica e na camada intermediária da região oeste do Oceano Atlântico Sul Tropical, ao longo da costa brasileira. A região estudada está delimitada pelas latitudes de 7°S e de 20°S. Determinouse que a área de geração da camada de salinidade máxima, encontrada a 100 m de profundidade nessa região, está situada ao sul de 15°S, extendendose até as proximidades de 20°S. A partir de modelos estacionários para o estudo da mistura de massas de água foi possível avaliar o coeficiente vertical de difusão turbulenta, para o núcleo da Água Intermediária Antártica, que está compreendido entre 5 cm2 .s-1 e 15 cm2 .s-1 Na Água Central do Atlântico Sul encontraramse os valores: 20 cm2 .s-1 e 13 cm2 .s-1, para os coeficientes verticais de condutividade térmica turbulenta e de difusão turbulenta de sal, respectivamente. O triângulo de contração do volume específico na mistura vertical, permitiu estudar a influência desse fenômeno na mistura da Água Intermediária Antártica com as massas de água que a envolvem. O valor máximo desse parâmetro foi encontrado na interface entre essa última massa de água e a Água Central do Atlântico Sul ( - 3,2.10-4 cm3 .g-1). / The purpose of this work is to present the fundanental theory of water masses analysis, based on the teraperature and salinity properties, and its utilization in great scale to waters of the oceanic troposphere and of the intermediate layer of the west region of the South Tropical Atlantic Ocean along the Brazilian coast. The region under study is limited by latitude 7°S and 20°S. It was deterinined that the source area of hi salinity layer, which is found at 100 m in depth in this region, is located to the south of 15°S, extending as far as 20°S. Based on stationary models for the study of water nesses mixture, it was possible to estimate the vertical coefficient of turbulent diffusion, for the core of Antarctic Intermediate Water, which is between 5 cm2 .s-1 and 15 cm2 .s-1. In the South Atlantic Certral Water values of 20 cm2 .s-1 and 13 cm2 .s-1 are found for the vertical coefficients of turbulent heat conduction and turbulent salinity diffusion, respectively. The triangle of the specific volume contraction in the vertical mixing permitted the study of the influence of this phenomenon on the mixture of the Antarctic Intermediate Water and the water masses that envolves it. The greatest value of this parameter was found in the interface of the latter and the South Atlantic Central Water ( - 3,2.10-4 cm3 .g-1).

O objetivo deste trabalho é apresentar a teoria fundamental da análise de massas de água baseada nas características temperatura e salinidade, e a sua aplicação, em grande escala, às águas que circulam na troposfera oceânica e na camada intermediária da região oeste do Oceano Atlântico Sul Tropical, ao longo da costa brasileira. A região estudada está delimitada pelas latitudes de 7°S e de 20°S. Determinouse que a área de geração da camada de salinidade máxima, encontrada a 100 m de profundidade nessa região, está situada ao sul de 15°S, extendendose até as proximidades de 20°S. A partir de modelos estacionários para o estudo da mistura de massas de água foi possível avaliar o coeficiente vertical de difusão turbulenta, para o núcleo da Água Intermediária Antártica, que está compreendido entre 5 cm2 .s-1 e 15 cm2 .s-1 Na Água Central do Atlântico Sul encontraramse os valores: 20 cm2 .s-1 e 13 cm2 .s-1, para os coeficientes verticais de condutividade térmica turbulenta e de difusão turbulenta de sal, respectivamente. O triângulo de contração do volume específico na mistura vertical, permitiu estudar a influência desse fenômeno na mistura da Água Intermediária Antártica com as massas de água que a envolvem. O valor máximo desse parâmetro foi encontrado na interface entre essa última massa de água e a Água Central do Atlântico Sul ( - 3,2.10-4 cm3 .g-1). / The purpose of this work is to present the fundanental theory of water masses analysis, based on the teraperature and salinity properties, and its utilization in great scale to waters of the oceanic troposphere and of the intermediate layer of the west region of the South Tropical Atlantic Ocean along the Brazilian coast. The region under study is limited by latitude 7°S and 20°S. It was deterinined that the source area of hi salinity layer, which is found at 100 m in depth in this region, is located to the south of 15°S, extending as far as 20°S. Based on stationary models for the study of water nesses mixture, it was possible to estimate the vertical coefficient of turbulent diffusion, for the core of Antarctic Intermediate Water, which is between 5 cm2 .s-1 and 15 cm2 .s-1. In the South Atlantic Certral Water values of 20 cm2 .s-1 and 13 cm2 .s-1 are found for the vertical coefficients of turbulent heat conduction and turbulent salinity diffusion, respectively. The triangle of the specific volume contraction in the vertical mixing permitted the study of the influence of this phenomenon on the mixture of the Antarctic Intermediate Water and the water masses that envolves it. The greatest value of this parameter was found in the interface of the latter and the South Atlantic Central Water ( - 3,2.10-4 cm3 .g-1).

Magister Artium - MA / For an Island measuring merely 128 square kilometers, and in spite of its remote location in the mid-­South Atlantic, St. Helena “punches way above its weight in history”, earning and occupying a privileged place in British scholarship of its imperial thalassocratic age. However, prior to this period in which the Island was indispensible to British Empire formation, it had passed through the hands of at least two former European naval nations before it was eventually laid claim to and effectively colonised by the British. The Portuguese, who were the first to stumble upon the uninhabited Island in 1502 -­ naming it St. Helena in honour of Roman Emperor Constantine the Great’s mother -­ managed to keep its existence a closely guarded secret for over eight years. For nearly a century, the Island was reserved for exclusive use by the Portuguese as a port for recuperation, replenishing and re-­provisioning, which they usually visited on their homebound journey from trading (and conquering) in the East Indies. This Portuguese monopoly of use of the Island, however, ended during the last decade of the sixteenth century when other maritime nations, particularly Dutch and later English traders, became aware of and started frequenting the Island. The initial overlap period, constituting the first three decades of the seventeenth century when mostly the Dutch and Portuguese shared use of the Island, was cause for occasional hostile encounters between the two nations. Apparently, continued Dutch and English harassment of Portuguese (and Spanish) ships made visiting the Island untenable for the Portuguese who opted to avoid St. Helena and instead make use of a number of their other port ‘possessions’ along the West African coastline to replenish and repair their ships.

Neste estudo a assembleia de cocolitoforídeos de 44 amostras de sedimentos marinhos de superfície da Margem Continental Brasileira foram analisados e comparados com os parâmetros oceanográficos locais. Com o intuito de obter um melhor entendimento da área de estudo, foram incluídas as análises de 36 amostras do estudo de Boeckel et al. (2006). A partir destes dados, os padrões de abundância das principais espécies e suas afinidades ecológicas foram verificadas. E. huxleyi, F. profunda e Gephyrocapsa spp. são as espécies mais abundantes. E. huxleyi dominou as assembleias características de águas mais frias e ricas em nutrientes, Gephyrocapsa spp. as regiões com menores profundidades da camada de mistura, ou seja, estas espécies demonstram uma preferência por uma nutriclina mais rasa. Por outro lado, F. profunda, foi mais abundante nas águas quentes e oligotróficas das regiões subtropicais, revelando sua preferência por uma nutriclina mais profunda. Além disso, os resultados da Análise de Correspondência Canônica revelaram uma afinidade de C. leptoporus, E. huxleyi, C. pelagicus e G ericsonii com águas mais enriquecidas em nutrientes. Em contraste, Gephyrocapsa spp. e Helicosphaera spp. foram associadas a regiões mesotróficas. Uma vez que G. flabellatus e D. tubifera parecem estar associadas a águas com camadas de mistura mais profundas, elas podem ser utilizadas, juntamente com F. profunda, como indicadoras de uma termo/nutriclina mais profunda. A partir de análise de clusters e análise por componentes principais, 4 províncias foram identificadas e parecem refletir as características oceanográficas da zona fótica. / In this study the coccolitophore assemblages of 44 samples of marine surface sediments from the Brazilian Continental Margin were analyzed and compared with the local oceanographic parameters. In order to obtain a better understanding of the study area, were included the analysis of 36 samples from the study by Boeckel et al. (2006). From these data, the abundance patterns of the main species and their ecological affinities were verified. E. huxleyi, F. profunda and Gephyrocapsa spp. are the most abundant species. E. huxleyi dominated the assemblages characteristic of colder and nutrient-rich waters, Gephyrocapsa spp. the regions with lower mixed layer depths, in other words, these species demonstrate a preference for a shallower nutricline. On the other hand, F. profunda, was more abundant in the warm and oligotrophic waters of the subtropical regions, revealing its preference for a deeper nutricline. In addition, the results of the Canonical Correspondence Analysis revealed an affinity of C. leptoporus, E. huxleyi, C. pelagicus and G ericsonii for waters enriched in nutrients. In contrast, Gephyrocapsa spp. and Helicosphaera spp. were associated with mesotrophic regions. Since G. flabellatus and D. tubifera appear to be associated with waters that have deeper mixed layers, they may be used, along with F. profunda, as indicators of a deeper nutricline. From the cluster analysis and by the principal components analysis, 4 provinces were identified and seems to reflect the oceanographic characteristics of the photic zone.

Neste estudo a assembleia de cocolitoforídeos de 44 amostras de sedimentos marinhos de superfície da Margem Continental Brasileira foram analisados e comparados com os parâmetros oceanográficos locais. Com o intuito de obter um melhor entendimento da área de estudo, foram incluídas as análises de 36 amostras do estudo de Boeckel et al. (2006). A partir destes dados, os padrões de abundância das principais espécies e suas afinidades ecológicas foram verificadas. E. huxleyi, F. profunda e Gephyrocapsa spp. são as espécies mais abundantes. E. huxleyi dominou as assembleias características de águas mais frias e ricas em nutrientes, Gephyrocapsa spp. as regiões com menores profundidades da camada de mistura, ou seja, estas espécies demonstram uma preferência por uma nutriclina mais rasa. Por outro lado, F. profunda, foi mais abundante nas águas quentes e oligotróficas das regiões subtropicais, revelando sua preferência por uma nutriclina mais profunda. Além disso, os resultados da Análise de Correspondência Canônica revelaram uma afinidade de C. leptoporus, E. huxleyi, C. pelagicus e G ericsonii com águas mais enriquecidas em nutrientes. Em contraste, Gephyrocapsa spp. e Helicosphaera spp. foram associadas a regiões mesotróficas. Uma vez que G. flabellatus e D. tubifera parecem estar associadas a águas com camadas de mistura mais profundas, elas podem ser utilizadas, juntamente com F. profunda, como indicadoras de uma termo/nutriclina mais profunda. A partir de análise de clusters e análise por componentes principais, 4 províncias foram identificadas e parecem refletir as características oceanográficas da zona fótica. / In this study the coccolitophore assemblages of 44 samples of marine surface sediments from the Brazilian Continental Margin were analyzed and compared with the local oceanographic parameters. In order to obtain a better understanding of the study area, were included the analysis of 36 samples from the study by Boeckel et al. (2006). From these data, the abundance patterns of the main species and their ecological affinities were verified. E. huxleyi, F. profunda and Gephyrocapsa spp. are the most abundant species. E. huxleyi dominated the assemblages characteristic of colder and nutrient-rich waters, Gephyrocapsa spp. the regions with lower mixed layer depths, in other words, these species demonstrate a preference for a shallower nutricline. On the other hand, F. profunda, was more abundant in the warm and oligotrophic waters of the subtropical regions, revealing its preference for a deeper nutricline. In addition, the results of the Canonical Correspondence Analysis revealed an affinity of C. leptoporus, E. huxleyi, C. pelagicus and G ericsonii for waters enriched in nutrients. In contrast, Gephyrocapsa spp. and Helicosphaera spp. were associated with mesotrophic regions. Since G. flabellatus and D. tubifera appear to be associated with waters that have deeper mixed layers, they may be used, along with F. profunda, as indicators of a deeper nutricline. From the cluster analysis and by the principal components analysis, 4 provinces were identified and seems to reflect the oceanographic characteristics of the photic zone.

It has been demonstrated that nitrogen fixation is a source of hydrogen (H2) to the ocean and therefore measurements of H2 concentrations may be used as a possible indicator of nitrogen fixation (Moore, Punshon, Mahaffey, & Karl, 2009). However, the limited number and sparse distribution of measurements of dissolved hydrogen and nitrogen fixation rates made in the open ocean in the past have made it difficult to quantify the relationship between them. Toward this end, a new method of equilibrating seawater samples for H2 measurement was employed along the 13,000 km Atlantic Meridional Transect (AMT20) from UK to Chile, allowing H¬2 to be measured from underway samples every 3.5 minutes and thereby considerably increasing the number and resolution of H2 measurements made in the open ocean.These high-resolution measurements reveal two regions with high H¬2 concentrations, one in the North Atlantic and one in the South Atlantic.

Thesis (M.A. National Security Affairs)--Naval Postgraduate School, 1990. / Thesis Advisor(s): Bruneau, Thomas C. Second Reader: Breemer, Jan S. "June 1990." DTIC Identifier(s): International politics, Treaties, Security, Cooperation, South America, South Africa, Competition, Natural resources, Sea lanes of communication, Naval operations, Foreign policy, Balance of power, Sovereignty, Spheres of influence, National interests. Author(s) subject terms: U.S. Interests, South Atlantic, Southern Cone, Antarctica. Includes bibliographical references (p. 101-104). Also available online.

Este trabalho tem por objetivo descrever a Anomalia Magnética do Atlântico Sul (SAMA) utilizando os modelos para o período histórico (1600–1890) e também os modelos para o último século (DGRF e IGRF). Como a SAMA apresenta características de baixa intensidade do campo total e coincide com a região de intenso fluxo de partículas cósmicas, muitos problemas com objetos que orbitam a Terra (por exemplo, satélites) são detectados nessa região. São descritos os efeitos provocados pela SAMA em fenômenos espaciais. Através da análise dos modelos na forma de mapas, foram extraídos os dados de mínima intensidade para o centro da SAMA e a posição destes pontos, possibilitando conhecer a trajetória e as taxas de deriva. Os modelos foram testados na interface manto-núcleo através da componente vertical, para encontrar correlação com anomalias em superfície. Os resultados mostraram deriva para Oeste constante e variações em latitude. Foi observado que as intensidades acompanham a diminuição de todo o campo, embora a SAMA apresente caráter predominantemente não-dipolar, evidenciada pela razão entre o campo não-dipolar e o campo total no Atlântico Sul. A comparação de intensidades da SAMA com as medidas de intensidade realizadas pelos observatórios mostrou que a influência da SAMA aparece na forma de sobreposição ou amplificação de fenômenos com menor comprimento de onda, como os impulsos de variação secular (jerks geomagnéticos). A continuação para baixo dos modelos se mostrou satisfatória quando comparada com o método de inversão estocástica. A comparação da SAMA com outras anomalias em superfície mostrou independência na trajetória, porém, quando comparadas com os lóbulos principais na interface manto-núcleo, indicam que estas anomalias possam estar interligadas. Os lóbulos do núcleo foram interpretados com base nos mecanismos de geração, sugerindo que a SAMA possa ser originada através de movimentos combinados entre duas colunas de convecção e regiões de fluxo reverso no núcleo externo. / The object of this dissertation is to describe the South Atlantic Magnetic Anomaly (SAMA) using geomagnetic models for the historical period from 1600 to 1890 and also the IGRF and DGRF models for the past century. Since the SAMA presents low intensities of the total geomagnetic field that correspond to a region of intense cosmic ray particle flux, many problems with objects that orbit along this region (eg. Satelites) have been detected. The SAMA effects on space vehicles are described. The field models led to the definition of the SAMA center as the locus of minimum total field intensity and how the anomaly drifted and varied in intensity for the past four centuries. The vertical component at the Core Mantle Boundary (CMB) was used to find correlations with anomalies at the surface the Earth surface. Results have shown a rather constant westward drift and also latitude variations. It was observed that intensities follow the general decrease of the total field although the SAMA displays a predominantly non-dipolar character that is evident in the non-dipolar/total field ratios for the South Atlantic. The comparison of geomagnetic measurements by nearby Southamerican Observatories show that the SAMA influence appears as a superposition or amplification of lower wavelength phenomena such as the secular variation impulses (jerks). A downward continuation of the models was found satisfactory when compared to the stochastic inversion method. The comparison of the SAMA with other surface anomalies showed a rather independent behavior however, a comparison with the main radial component lobes at the CMB showed that all these anomalies may be interconnected. The nucleus lobes have been interpreted under the light of field generation processes, suggesting that the SAMA may originate from the combined motion of two convection columns and reverse flux regions in the outer core.

With the latest reauthorization of the Magnuson-Stevens Fishery Conservation and Management Act (MSA) and the precarious state of many of the nation's fisheries, it has become essential to incorporate uncertainty in the process of setting annual catch limits (ACLs) and annual catch targets (ACTs). The accuracy with which we predict landings can be thought of as management uncertainty, and it can be estimated by comparing the predicted landings intended by a regulation to the fisheries\' actual landings estimates. The National Standard 1 Guidelines for the MSA state that management regulations should take into account management uncertainty when establishing ACLs or ACTs, prescribing more precaution when management uncertainty is high. This study compared pre-season landings predictions of managed fish species in the South Atlantic to post-season estimates and investigated the existence of management uncertainty, and evaluated its magnitude and direction. Results indicate that the magnitude of management uncertainty for some stocks in the region may be significant. It appears that recreational fisheries have significantly greater management uncertainty than commercial fisheries, and that commercial fisheries are often producing landings smaller than intended or predicted. No relationship was found between regulatory mechanism or the magnitude of a fishery and management uncertainty. The study also revealed that documentation of the methodology used to determine preseason catch estimates is often not sufficient to repeat estimation procedures. The results of this study will have immediate and direct utility in the setting of future management regulations, ACLs, and ACTs in the South Atlantic region, and perhaps beyond. / Master of Science