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Formation and Maintenance of the Southern Bay of Bengal Cold PoolDas, Umasankar January 2015 (has links) (PDF)
Around Sri Lanka and to the south of India sea surface temperatures (SST) are cooler compared to the surrounding region during summer monsoon. This region where SSTs are relatively cooler is known as the cold pool. Owing to its possible impact on monsoon variability, some studies have been carried out to understand the evolution of cold pool SST during this period. These studies suggest, coastal upwelling along southern coast of Sri Lanka and eastward advection of cooler water contributes to the decrease in SST during summer monsoon. However, the processes leading to the formation of cold pool, still, remain unknown.
In this study, we have investigated the mechanism responsible for the formation and maintenance of southern Bay of Bengal (BOB) cold pool using high resolution satellite data, model simulations and in-situ observations for the year 2009. Our study reveals formation of cold pool is dominated by atmospheric processes, whereas oceanic processes dominate its maintenance.
Cooling of SSTs during premonsoon and onset phase acts as a prerequisites for the formation of cold pool, which are linked to the reduction in Net Heat flux (NHFX) during theses periods. The changes in NHFX during premonsoon and onset phase are dominated by reduction in Short-wave (SW) radiation associated with strong convective activity over cold pool. Convective activity over the cold pool are associated with the northward movement of Maximum Cloud Zone (MCZ) that forms over Equatorial Indian Ocean (EIO) during these periods. SST within the cold pool after the steady increase during February-April months, cools first during premonsoon rain event and then during monsoon onset. Analysis of high resolution satellite data for the period 2003-2009 suggest that, these sequence of events occurs with minor amount of inter-annual variability. Lead-lag correlation also made it clear that SST response in 5 days to the corresponding variation in atmospheric processes.
SST within the cold pool shows several intraseasonal cooling events during the summer mon-soon. Considering that rainfall above the cold pool is very low during the summer monsoon, these cooling events occurring within the summer should be necessary for maintaining the cold pool. The seasonal evolution of SST shows that it continues to decrease till the end of the summer monsoon. In-situ data collected during CTCZ field program in 2009, at two time series locations (TSL) and model simulations were used to determine the processes responsible for such cooling events. To estimate the contribution from advection to the observed SST tendency at fixed location, a measurement stratergy called ‘opertaion advection’ was used in this study. This stratergy involves measurement of oceanographic parameters along four edges from TSL directod along North, South, East and West for estimation of horizontal temperature gradients. Our results from SST cooling events captured by CTD at two fixed locations suggests that horizontal advection and entrainment dominate the SST evolution. Model temperature equation evaluated near the TSLs are convinient with the observations and suggest that atmospheric forcing is not responsible for intraseasonal cooling events.
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Contribution de IASI à l’estimation des paramètres des surfaces continentales pour la prévision numérique du temps / IASI contribution to land surface parameter retrievals for numerical weather predictionVincensini, Anaïs 19 December 2013 (has links)
Le sondeur infrarouge hyperspectral IASI (Interféromètre Atmosphérique de Sondage Infrarouge), développé conjointement par le CNES et EUMETSAT à bord du satellite européen Metop, permet, entre autres, le sondage de la température, de l'humidité ainsi que la restitution de paramètres de surface. Bien que l'on tire le meilleur parti de ces données sur la mer, leur utilisation est encore limitée au-dessus des terres dans le contexte de la prévision numérique du temps, à cause de l'incertitude plus grande sur l'émissivité et la température de surface (Ts). Ces erreurs se répercutent sur la qualité des simulations de transfert radiatif et empêche l'utilisation de ces mesures dans les modèles de prévision numérique du temps. Seuls les canaux non sensibles à la surface terrestre sont assimilés de façon opérationnelle, limitant ainsi le potentiel de sondage aux couches atmosphériques les plus élevées. Cette thèse a pour but l'amélioration de la description des paramètres de surface dans le modèle global ARPEGE de Météo-France en vue de l'assimilation des données du sondeur IASI sur les continents. Nous avons d'abord cherché à améliorer la modélisation de la surface (émissivité et Ts) sur les continents dans le modèle ARPEGE. Pour cela, différents atlas d'émissivité ont été intégrés dans ce modèle : l'un a été calculé à partir des données MODIS (Moderate-Resolution Imaging Spectroradiometer) par l'Université du Wisconsin et le second a été construit à partir des produits IASI de niveau 2 (L2) développés par EUMETSAT. La Ts a ensuite été restituée à partir de canaux de surface IASI en profitant d'une meilleure connaissance de l'émissivité de surface donnée par ces atlas. Ces Ts ont été évaluées par comparaison avec les produits MODIS de la NASA et les produits IASI L2 d'EUMETSAT. Ces comparaisons nous ont permis de sélectionner une combinaison de canaux qui fournit les meilleures estimations de Ts. L'utilisation d'une modélisation de surface réaliste a contribué à l'amélioration de la qualité des simulations de transfert radiatif pour les canaux sensibles à la surface. Les radiances IASI sensibles à la surface ont alors pu être assimilées sur les continents dans le modèle ARPEGE en ciel clair et en utilisant la paramétrisation de surface définie précédemment. Les impacts sur la qualité des analyses et des prévisions ont été étudiés. La prise en compte d'une émissivité et d'une Ts précises a permis d'augmenter significativement le nombre d'observations assimilées. Les principales améliorations concernent les prévisions de géopotentiel et de température pour des pressions inférieures à 400~hPa (en dehors des tropiques). Enfin, dans un cadre plus spécifique et climatologique, nous nous sommes intéressés à la validation de l'utilisation des données IASI en Antarctique durant la campagne Concordiasi. Cette étude a permis d'améliorer les profils inversés de température et de vapeur d'eau par comparaison avec les profils provenant du modèle. L'amélioration est particulièrement importante pour la température de surface. Dans ce cadre, les Ts restituées dans cette thèse ont été comparées à Concordia et au Pôle Sud avec des mesures in-situ et se sont révélées particulièrement précises à Concordia. / The Infrared Atmospheric Sounding Interferometer (IASI), on-board the EUMETSAT Polar System Metop satellite, is developed by CNES in the framework of a co-operation agreement with EUMETSAT. IASI enables, amongst other, infrared soundings of temperature, moisture and retrievals of surface parameters. However in the numerical weather prediction context, these observations are not as intensively used over land as they are over sea because of larger uncertainties about land emissivity and land surface temperature (LST). These uncertainties have an impact on the quality of radiative transfer simulation and hinder the use of these measurements in numerical weather prediction models. Only channels that are not sensitive to the surface are currently assimilated in operations, which limits the potential of sounding instruments to the highest atmospheric layers. This PhD aims to improve the description of land surface parameters in the ARPEGE global model of Météo-France to assimilate IASI data over land. First of all, we tried to improve the surface modelling (surface emissivity and LST) over land in the ARPEGE model. To this end, two emissivity atlases were integrated in this model. The first one is the emissivity climatology computed from the IASI Level-2 products from EUMETSAT and the second one is the global high spectral resolution infrared land surface emissivity database (called UWIREMIS) developed by the Space Science and Engineering Center at University of Wisconsin. Hence, the LST was retrieved from IASI surface channels using these atlases as input parameters in the radiative transfer model. These LSTs were compared to land LST products: the MODIS (Moderate-Resolution Imaging Spectroradiometer) products from the NASA and the IASI Level-2 products from EUMETSAT. These comparisons enabled us to choose the IASI channel combination that provided the best LST estimates. The use of a realistic surface modelling contributed to improve the quality of radiative transfer simulations for surface sensitive channels. Then, surface sensitive IASI radiances were assimilated over land in ARPEGE in clear sky conditions using the surface parameters as previously defined. The impact on analysis and forecast quality was studied. The use of good estimates of surface emissivity and LST significantly increased the number of assimilated observations. The main improvements are for geopotential and temperature forecasts for pressure levels lower than 400~hPa (except in the tropics and in the stratosphere). Finally, from a climatological point of view and within the more specific framework of the Concordiasi campaign, we assessed and validated the use of IASI data in Antarctica. The temperature and humidity retrieved in this particular study proved of better quality than the model profiles, as assessed against the sonde measurements. The improvement is particularly striking for surface temperature. In this framework, the LST retrieved in this PhD were compared with in situ measurements at Concordia and at South Pole station. These estimates are of a great accuracy at Concordia.
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Variabilidade climática espectral da temperatura da superfície do mar e sua associação com o clima da América do Sul / Spectral climatic variability of global sea surface temperature and its association with the climate in South AmericaSilva, Carlos Batista da 05 September 2017 (has links)
O objetivo deste estudo foi analisar a variabilidade climática espectral da temperatura da superfície do mar, TSM, global associada a oscilações de 1-12 meses, 1-2 anos, 2-4 anos, 4-8 anos e 8-12 anos, entre1854 e 2014, e, as possíveis relações com a variabilidade climática na América do Sul. A análise espectral da TSM foi obtida com a aplicação da técnica de ondeletas a dados mensais. Em termos globais, as bacias tropicais do Pacífico Norte e Sul apresentam os sinais mais intensos da variância de TSM, em todas as faixas espectrais consideradas, e, portanto, valores mais próximos da média global para os trópicos, indicando a importância do oceano Pacífico no clima global. Nesta ordem, as bacias do Pacífico Sul, Pacífico Norte, Atlântico Norte, Indico e Atlântico Sul apresentam valores decrescente de variância da TSM. A análise da tendência linear ao longo do período considerado mostra que, globalmente, fenômenos tropicais com oscilações nas escalas de frequências mais altas, 1-12 meses, 1-2 anos e 2-4 anos, têm apresentado decréscimo de energia e que fenômenos com oscilações nas escalas de frequências mais baixas, 4-8 e 8-12 anos, têm apresentado aumento de energia, o que sugere a troca de energia entre fenômenos de alta e baixa frequência . As oscilações de 2-4 anos e de 4-8 anos na região equatorial do Pacífico são as que apresentam os maiores valores de energia, em especial nas regiões de Ninõ1+2, Niño3, Niño3.4 e Niño4. Os resultados permitem verificar que eventos fortes de El Niño sempre estiveram associados a sinais intensos da variância de TSM nas faixas espectrais de 2-4 anos e 4-8 anos e que os eventos mais fracos de El Niño estiveram associados à faixa de oscilações mais rápidas, 1-2 anos. O início do aumento do valor da variância de TSM para oscilações de 2-4 anos e 4-8 anos na região equatorial do Pacífico apresenta, em todos os casos, antecedência significativa em relação à ocorrência de um evento de El Niño forte, indicando a possibilidade de usar este sinal como preditor da ocorrência de eventos quentes de ENOS. A associação entre a variabilidade da variância espectral de TSM e a variabilidade climática na América do Sul foi verificada com base nos dados precipitação do GPCC, dados de vento das reanálises I e II do NCEP-NCAR e da reanálise do JRA-55. A análise de ondeletas da TSM tropical para a faixa de oscilações de 4-8 anos possibilitou a divisão do período todo em fases distintas: fases positivas, 1948 a 1960 e 1982 a 2003 e fases negativas, 1961 a 1981 e 2004 a 2014. Observou-se que as fases positivas e negativas apresentam um padrão bipolar da precipitação entre as regiões nordeste e sudeste da América do Sul, o que está associado a anomalias contrárias da circulação atmosférica em altos e baixos níveis sobre a região central do continente, constituindo um resultado inédito na área de climatologia. As fases positivas da variância de TSM para oscilações de 4-8 anos estão associadas a anomalias negativas e positivas de precipitação, respectivamente, sobre as regiões nordeste e sudeste da América do Sul enquanto que as fases negativas estão associadas a padrões contrários. O padrão do 4º modo da Análise de Componentes Principais aplicada aos dados de vento em 200 hPa contribui para explicar fisicamente o padrão bipolar da precipitação observado no setor leste do continente na escala decadal, por meio da propagação de ondas de baixa frequência entre o Pacífico Sul e a América do Sul. / The aim of this study is to analyze the global SST spectral climate variability for 1-12 month, 1-2 year, 2-4 year, 4-8 year, and 8-12 year oscillations, in the period from 1854 to 2014, and the possible relations with the climatic variability in South America. The spectral analysis of SST was obtained with the application of the wavelet technique to the monthly data. In global terms, the North and South Pacific basins show the most intense signs of SST variance in all the spectral ranges considered, and therefore, values closer to the global average, indicating the importance of the Pacific Ocean in the global climate. Then, in order of importance, come the basins of the South Pacific, the North Pacific, the North Atlantic, the Indian Ocean and the South Atlantic. The analysis of the linear trend throughout the period considered shows that globally within the tropical range, phenomena with oscillations in the scales of higher frequencies, 1-12 months, 1-2 years, and 2-4 years, have decreased energy and that phenomena with oscillations at lower frequency scales, 4-8 and 8-12 years, have presented increased energy through the course of time, suggesting energy exchange between high frequency phenomena and low frequency phenomena. The 2-4 year and 4-8 year oscillations in the equatorial Pacific region are those with the highest energy values, especially in the Nin1 + 2, Niño3, Niño3.4 and Niño4 regions. It is also possible to verify that strong El Niño events have always been associated with intense SST variance signals in the 2-4 year and 4-8 year spectral bands, and the weaker El Niño events were associated with the 1-2 year spectral bands. The beginning of the increase in the SST variance value for 2-4 year and 4-8 year oscillations in the equatorial region of the Pacific presents, in all cases, significant antecedence in relation to the occurrence of a strong El Niño event, indicating the possibility of using this signal as a predictor of the occurrence of hot ENSO events. The association between SST spectral variance variability and climatic variability in South America was verified based on GPCC precipitation data and wind data from NCEP-NCAR I and II reanalyses and of the JRA-55 reanalysis. The analysis of tropical SST wavelets for the 4-8 year oscillation range allowed the division of the whole period into distinct phases: positive phases, 1948 to 1960 and 1982 to 2003; and negative phases, 1961 to 1981 and 2004 to 2014. It was observed that positive and negative phases present a bipolar precipitation pattern between the Northeast and Southeast regions of the AS, which is associated with anomalies of atmospheric circulation at high and low levels over the central region of the continent, which is an unprecedented result area of climatology. The positive phases of the SST variance for 4-8 year oscillations are associated with negative and positive precipitation anomalies respectively over the northeast and southeast regions of South America while the negative phases are associated with contrary precipitation patterns. The 4th mode pattern of the Principal Component Analysis applied to wind data at 200 hPa contributes to physically explaining the bipolar pattern of precipitation observed in the eastern sector of the continent on the decadal scale by propagating low frequency waves between the South Pacific and South America.
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Variabilidade oceânica associada à variabilidade climática da vazão na bacia do rio São Francisco / Oceanic variability related to river outflow at São Francisco Hydrographic basinCosta, Karine Mirieli dos Santos 06 February 2012 (has links)
Esta pesquisa tem como objetivo avaliar a relação existente entre o comportamento anual dos oceanos e o da vazão na Bacia do Rio São Francisco, Brasil, para o período de 1968 a 2004. Foram construídos modelos de regressão linear múltipla para simular o valor da vazão anual em Ponte da Taquara, Alto São Francisco, com base em índices climáticos e no valor médio da Temperatura da Superfície do Mar (TSM) em áreas específicas dos oceanos Pacífico e Atlântico. Os índices climáticos considerados foram a Oscilação Decadal do Pacífico (ODP), Indice de Oscilação Sul (IOS) e anomalias de TSM nas regiões de Niño. Os padrões oceânicos de correlação linear entre a TSM do Pacífico e a vazão dos postos do Alto São Francisco e o Médio São Francisco, indicam valores positivos em toda a costa oeste da América do Norte e do Sul e região equatorial e fortes sinais negativos na costa leste da Ásia e Austrália. Este padrão é bastante semelhante ao padrão espacial do primeiro modo obtido pela aplicação de análise multivariada à TSM no Oceano Pacífico, que é associado à Oscilação Multidecadal do Pacífico. A consideração de defasagem mensal no cálculo do coeficiente de correlação linear entre os valores de vazão e TSM indicam que a TSM dos meses mais próximos ao da vazão têm maior potencial para serem considerados como seus preditores. Observa-se a diminuição da correlação linear entre TSM do Pacífico e a vazão dos postos do Médio e Baixo São Francisco em relação aos postos do Alto São Francisco. O que sugere que o Oceano Pacífico apresenta maior influência na variabilidade da vazão nos postos localizados mais ao sul da Bacia do São Francisco. Por outro lado, observa-se o aumento dos valores do coeficiente de correlação linear no Atlântico Sul principalmente para a vazão dos postos do Médio e Sub-Médio, indicando possivelmente a maior influência do Oceano Atlântico na vazão de postos localizados mais a nordeste da bacia hidrográfica considerada. O padrão oceânico indicado pelos valores de correlação linear entre a TSM e os postos do Sub- Médio São Francisco indica a presença de um dipolo meridional, com anomalias negativas e positivas na bacia do Atlântico Sul tropical e subtropical. O IOS e ODP apresentam maior valor de correlação para a vazão observada no Alto e Médio São Francisco. As regiões selecionadas nos oceanos Pacífico, Atlântico e Índico e os índices Niño1+2, Niño 3 e Niño 4 para a construção do modelo linear para a simulação da vazão anual suavizada explicam 96% da variância total da vazão. No caso da vazão sem suavização as variáveis selecionadas pelo modelo elaborado explicam 52% da variância total. O padrão atmosférico anômalo associado aos dois primeiros subperíodos da vazão em Ponte da Taquara, de 1968 a 1978 e de 1979 a 1988, caracterizados em média por anomalias negativas e positivas, respectivamente, apresenta condições atmosféricas específicas às anomalias observadas da vazão. Em geral, anomalias negativas (positivas) de vazão em Ponte da Taquara são acompanhadas por ODP negativa, com anomalias negativas (positivas) de TSM no Pacífico Equatorial. / This research concerned to propose a valuation about the relationship between annual oceanic behavior and river outflow at São Francisco Hydrographic Basin, in Brazil, for the period from 1968 to 2004. Linear model based on multiple regression were built for annual river outflow at Ponte da Taquara, located at High São Francisco sub-basin. Climatic indexes and Sea Surface Temperature (SST) averages for selected areas over Pacific and Atlantic oceans were taken as independent variables in the modeling. Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI) and SST anomalies at the Niño regions were also considered as independent variables in the modeling. The specific oceanic areas were selected through linear correlation calculation between river outflow at High São Francisco and SST. Oceanic patter represented by linear correlation between Pacific SST and river outflow at High São Francisco and Medium São Francisco shows positive values throughout the west coast of North and South America and the equatorial areas and, high negative values at oceanic areas to the east of Asia and Australia. This patter is quite similar to that obtained as the first mode of multivariate analysis applied over Pacific basin, and is related to the PDO. The consideration of temporal lag between SST river outflow monthly values showed that the smaller interval provide the best linear correlation. Linear correlation patter over Pacific is more significant for river outflow observed at the southern area of São Francisco Basin in relation to those located at northern areas. This aspect suggests that Pacific Ocean plays a more significant role to determination of river outflow observed at the south of the hydrographic basin. On the other hand, linear correlation values are greater at South Atlantic when river outflow for Sub-Medium São Francisco is considered. This result suggests that South Atlantic Ocean can play a greater role for the determination for climatic variability for river outflow observed at northern areas of São Francisco Basin. The oceanic correlation pattern for South Atlantic Ocean also shows a dipole mode, between tropical and subtropical latitudes, for fluvial stations located at the northern areas of the hydrographic basin. SOI and PDO present greater correlation values for river outflow observed at High and Medium São Francisco Basin. Ocean Pacific, Atlantic and Indian and the indexes Niño1+2, Niño 3 e Niño 4 variables, selected for the linear model elaboration to river outflow simulation, explain 96% of the total variance. In the case of not smoothed data, the variance explained by the linear model is equal to 52%. The atmospheric averaged patterns for the considered two first subperiods, from 1968 to 1978 and from 1979 to 1988, that are characterized by negative and positive river outflow anomalies at High São Francisco, present atmospheric conditions closely related to the observed river outflow anomalies. In general, river outflow negative (positive) anomalies at High São Francisco are related to negative PDO and SST negative anomalies (positive) at equatorial Pacific.
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Meso- und mikroskalige Untersuchungen der Landoberflächentemperaturen von BerlinWeber, Nadine 05 August 2009 (has links)
Städtische Gebiete unterscheiden sich von Flächen mit ruraler Prägung, im Ergebnis sind sie stark modifiziert bezüglich ihrer Strahlungs- und Energiebilanz. In der vorliegenden Arbeit werden die Oberflächentemperaturen der Metropole Berlin im Mesomaßstab, unter Verwendung von Satellitenaufnahmen der ASTER- und Landsat-5- und 7-Sensoren untersucht sowie durch zusätzliche Messungen mit einer Thermalbildkamera über einen Zeitraum von 17 Monaten im Mikromaßstab erweitert. Diese Daten kombiniert mit GIS-basierten Informationen über die Landnutzungs- und Strukturtypen werden für die Analyse der räumlichen und zeitlichen Verteilung der Oberflächentemperaturen genutzt ebenso wie zur Ermittlung funktioneller Beziehungen zwischen dem thermischen Verhalten der Oberflächen und der zugehörigen Stadtstruktur. Bei der Auswertung geht es vorrangig um physikalische Prozesse und Eigenschaften, die einen Einfluss auf energetische Flüsse und ihre Interaktion mit städtischen Oberflächen haben. Eine thermische Charakteristik einzelner Bezirke über verschiedene Nutzungsklassen bis hin zu einzelnen Materialien wird erstellt. Dabei sind Temperaturdifferenzen von mehreren zehntel Kelvin zwischen den typischen städtischen Oberflächen Dächern und Rasenflächen zu beobachten. Die Resultate zeigen, dass die Verteilung der LST sehr verschieden ist und stark korreliert mit den Landbedeckungen. Es wird dargestellt, welche Stadtstrukturen besonders thermisch belastet sind, welche individuelle thermische Bedeutung einzelne Materialien haben. Besonderes Augenmerk wird auf Möglichkeiten der Beeinflussung durch Abschattung gelegt. Durch Verschattung können Differenzen der Oberflächentemperaturen von mehr als 10 Kelvin erreicht werden. Abschließend werden Modellierungen zur Verifizierung der Kameramessungen sowie zum Aufzeigen des Einflusses minimaler Änderungen in kleinräumigen Klimaten genutzt. / Urban areas differ from surfaces of rural character. They are very modified in their radiation- and energy balance. In this study land-surface temperatures of the city of Berlin are analyzed with the help of satellite pictures of the ASTER- and Landsat-5 and -7 sensors in mesoscale and then extended by extra measurements of an infrared camera in microscale over the course of 17 months. This data combined with GIS based information on different land use and -structures are used for the analysis of spatial and time distribution, as well as for the determination of functional relations between thermal behaviour of surfaces and the related urban structures. The evaluation mainly deals with physical processes and properties that have an influence on energetic flows and their interactions with urban surfaces. A thermal characteristic of individual districts, from different land use classes to specific materials is being created. In this there are differences in temperature of several tenths Kelvin between the typical urban surfaces of roofs and grass areas visible. The results show that the distribution of the LST varies immensely and correlates with the land coverage. It is shown, what urban structures are most thermic burdened, what individual significance specific materials have. Special attention is paid to the different possibilities of the influence through shadow. It is possible to reach a difference of surface temperatures of more than 10 Kelvin by shadow. At the end models with the 3-dimensional ENVImet are used to verify the camera measurements as well as to show the influence of minimal changes in microscale climate.
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Variabilidade da radiação em ondas longas em uma cidade de porte médio: experimentos nos espaços livres em São Carlos - SP / Variability of longwave radiation in a midsize city: experiments in free spaces in São Carlos - SPNeves, Gustavo Zen de Figueiredo 01 December 2014 (has links)
O balanço de energia e o fluxo radiativo produzidos nas superfícies urbanas não são objetos de muitos estudos no Brasil. Este trabalho objetivou verificar a variabilidade dos fluxos de energia em ondas longas em uma cidade Tropical de Altitude de porte médio. A metodologia fundamenta-se na utilização de um termômetro digital infravermelho fixado em um tripé, com a aferição manual de pontos cardeais e colaterais nas inclinações de -10º, 0º, 10º, 25º e 35º, em diversas classificações do uso do solo urbano definidas pelo Laboratório Quadro do Paisagismo do Brasil - QUAPÁ. Realizaram-se onze experimentos de campo na cidade de São Carlos-SP em episódios climáticos representativos de Inverno e Verão. As invasões polares na cidade de estudo, em fase de domínio, impõem as condições iniciais dos tipos de tempo com valores termais de superfície mais brandos quando comparados com a fase tropicalizada. Nas pesquisas de campo as temperaturas mais elevadas foram registradas para as angulações -10º e 0º altura aproximada ao nível do pedestre. Os padrões térmicos observados in situ foram correspondentes para algumas tipologias e outras não, pois dependem de fatores multi escalares como advecção, camada intraurbana, fluxos de calor sensível e calor latente. / The energy balance and the radiative flux produced in urban areas are not objects of many studies in Brazil. This research aimed to determine the variability of flows of energy in long waves in a Tropical midsize city. The methodology is based on the use of an infrared digital thermometer fixed on a tripod, with the manual measurement of cardinal points and the side slopes of - 10º, 0°, 10º, 25º, and 35º, in various classifications of urban land use defined by the Laboratory Quadro do Paisagismo do Brazil - QUAPÁ. Has been made in São Carlos -SP eleven field trials representative climatic episodes in winter and summer. The polar invasions in the city of study, in phase of domain, imposes the initial conditions of weather types with thermal values surface over mild compared with the tropicalized phase. In field trials the highest temperatures were recorded for the angles -10° and 0° to the approximate height of the pedestrian level. The thermal patterns observed in local were corresponding to some classifications and not to others, because they depend on multi scalar factors as advection, intraurban layer, flows sensible heat and latent heat.
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Variabilidade climática do oeste paulista e suas ligações com a temperatura da superfície do mar dos oceanos Pacífico e Atlântico / Climatic variability at the western of São Paulo state and its relation to sea surface temperature on Pacific and Atlantic oceansIkefuti, Priscilla Venâncio 22 June 2012 (has links)
Vários estudos fornecem evidências de que os oceanos Atlântico e Pacífico desempenham papel significativo nas flutuações climáticas que ocorrem no Brasil. O objetivo desta pesquisa é avaliar a relação entre a temperatura da superfície do mar, TSM, dos oceanos Pacífico e Atlântico e a vazão de rios localizados no oeste do estado de São Paulo. Foram analisados 30 anos de dados, de 1979 a 2008. Os dados de vazão foram obtidos da Agência Nacional de Águas, os dados da temperatura da superfície do mar e radiação de onda longa emergente, do CDC/NOAA, e as variáveis climáticas (temperatura mínima, média e máxima, precipitação e umidade relativa) foram obtidos do INMET e referem-se aos dados observados na estação meteorológica da cidade de Presidente Prudente. Os resultados foram obtidos pela estimativa da correlação linear entre as séries mensais de vazão e dos dados climáticos com a temperatura da superfície do mar nos oceanos, com e sem defasagem temporal. Áreas com correlação alta e significativa foram encontradas no oceano Pacífico e Atlântico. Os padrões oceânicos obtidos para os quatro postos de vazão se assemelham entre si, sugerindo que a variabilidade climática dos postos é parecida. O padrão de ferradura no Oceano Pacífico Tropical está presente em todos os casos avaliados, assim como áreas meridionalmente adjacentes com sinais trocados no setor norte do Atlântico Norte. No Oceano Atlântico, as principais áreas de correlações linear foram encontradas no hemisfério sul, indicando valores positivos. As correlações entre a TSM e as variáveis climáticas (temperaturas, umidade relativa, precipitação e ROLE) também apresentaram correlações significativas no Pacífico Tropical, indicando o padrão de ferradura. O modelo estocástico construído para simulação da vazão trimestral, em Presidente Prudente, com base em regressão linear múltipla forneceu um ajuste com explicação da variância igual a 49%. O modelo construído considerando-se as variáveis oceânicas e continentais fornece uma explicação da variância igual a 69%. Tal resultado sugere que seja possível considerar apenas variáveis oceânicas na elaboração de um modelo prognóstico para a vazão trimestral. Os períodos com anomalias positivas de vazão estiveram associados a maior convergência (divergência) do ar em baixos (altos) níveis, à intensificação do movimento vertical ascendente e movimento vertical ascendente intensificado. / Several studies provide evidence that the Atlantic and Pacific oceans play a significant role inclimate fluctuations that occur in Brazil. The objective of this research is to evaluate the relationship between sea surface temperature, SST, on Pacific and Atlantic oceans, and the observed river outflow in the western state of Sao Paulo. We analyzed 30 years of data, from 1979 to 2008. The river outflow data were obtained from the National Water Agency, the data of sea surface temperature and emergent longwave radiation, from the CDC / NOAA, and climatic variables (minimum, mean and maximum temperature, precipitation and relative humidity) were obtained from INMET. The latter refers to observed data in the meteorological station of the city of Presidente Prudente. The results were obtained by estimating the linear correlation between monthly series of river outflow data, climate data and sea surface temperature in the oceans, with and without lag. Areas with high and significant correlations were found in the Pacific and Atlantic oceans. The ocean patterns obtained for the four river outflow stations resemble each other, suggesting that the variability of the climate stations is similar. The pattern of \"horseshoe\" in the Tropical Pacific Ocean is present in all cases investigated, as well as areas meridionally adjacent and presenting opposite signs at the northern of North Atlantic. In the Atlantic Ocean, the main areas of linear correlations were found at the southern hemisphere, indicating positive values. The correlations between SST and climatic variables (precipitation and ROLE) also presented significant correlations values on Tropical Pacific, depicting the horseshoe pattern. The stochastic model built to simulate the quarterly river outflow, in Presidente Prudente, based on multiple linear regression, provided a fit that explained 49% of river outflow variance. The built model considering oceanic and continental variables provides an explanation of 69%. This result suggests that it is possible to consider only oceanic variables in the development of prognostic models for quarterly river outflow atthe region.The periods with positive river outflow anomalies were associated with greater air convergence (divergence) at low (high) levels and intensified upward movement.
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Fugacidade de CO2, massas d'água e bombeamento de Ekman no Oceano Atlântico SudoesteReis, Rafael Afonso do Nascimento January 2016 (has links)
O trabalho aqui apresentado utiliza dados da fugacidade de CO2 (fCO2) coletados por onze cruzeiros oceanográficos no Oceano Atlântico Sudoeste (OAS) que fazem parte do banco de dados do SOCAT para analisar a variabilidade espacial da fCO2 e as principais variáveis relacionadas a suas variações. Foram utilizados dados do satélite AQUA para se estudar a fCO2 sobre os campos médios mensais de temperatura da superfície do mar (TSM) e concentração de clorofila. Também foram utilizados dados de reanálise para descrever os campos de vento e pressão atmosférica em superfície durante o período de cada cruzeiro. Através dos dados de vento em superfície foram calculados os campos de bombeamento de Ekman. Os resultados demonstram que a principal variável responsável pelas variações da fCO2 foi a TSM (em geral com coeficiente de correlação r>0,8) e que as distintas massas d'água na região apresentam diferentes fCO2, sendo que as massas d'água mais quentes apresentam valores mais elevados que as mais frias. As águas da Pluma do Rio da Prata apresentam uma fCO2 que chega a ser ate 1,5 vezes maior que as outras massas d'água. Descreve-se, pela primeira vez no OAS, a importância de se considerarem os padrões de vento em superfície (através do bombeamento de Ekman) e não somente os valores de TSM e concentração de clorofila para uma melhor análise da fCO2 em relação às massas d'água no OAS. / The work presented here uses CO2 fugacity data (fCO2) collected by eleven oceanographic cruises in the Southwestern Atlantic Ocean (SAO) that are part of the SOCAT database to analyze the spatial variability of the fCO2 and the main variables related to its variations. AQUA satellite data were used to study the fCO2 over the monthly averaged sea surface temperature (SST) and chlorophyll concentration fields. Reanalysis data were also used to describe the wind and surface atmospheric pressure fields during the period of each cruise. Through the surface wind data, the Ekman pumping fields were calculated. The results show that the main variable responsible for fCO2 variations was SST (in general with a correlation coefficient r> 0.8) and that the different water masses in the region present different fCO2, with the warmer water masses presenting higher values than the cold ones. The waters of the La Plata Plume present a fCO2 that is up to 1.5 times higher than the other water masses. It is described for the first time in OAS the importance of considering the surface wind patterns (through Ekman pumping) and not only the values of SST and chlorophyll concentration for a better analysis of fCO2 in relation to the water masses in the OAS.
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Investigating the potential of remote sensing for long-term limnological analysis at pan-continental scalesPoliti, Eirini January 2010 (has links)
Lakes are key indicators of environmental change and major repositories of biodiversity and ecosystem services. However, studies of lake response to drivers of change at a pan-European scale are exceptionally rare. The need for such studies has been given renewed impetus by concerns over climate change and because of international policyrelated schemes, such as the EU Water Framework Directive that has made it legal requirement to repeatedly assess and monitor the ecological status of European lakes toward their effective management and sustainable use. This has introduced the need for methods that can be widely applied across large spatial and temporal scales and produce comparable results. Remote sensing is a promising method for providing such information, but the spatial transferability and temporal repeatability of methods and relationships observed remains untested. In this project, an extensive dataset of field measurements was compiled covering temperature, chlorophyll a and Secchi disk depth in 23 European lakes spanning the last 30 years. The characteristics of these lake systems were explored and similarities in their ecological behavior identified, thus providing the basis for their grouping. Then the potential of remote sensing for estimating and monitoring lake water quality at wide spatial and temporal scales was assessed and thus the long remote sensing archive at the NEODAAS DSRS was fundamental for the purposes of this project. Using NOAA AVHRR, Terra/Aqua MODIS and field data from lakes that represented three main lake groups, the spatial and temporal reliability of 26 existing water quality estimation algorithms was assessed. Following this, the best performing algorithms were applied to all study sites and the effect of scale and spatial resolution upon reliable estimation of key water quality parameters was evaluated. It was demonstrated that the NOAA AVHRR and Terra/Aqua MODIS were both capable of producing highly accurate (R2 > 0.9) lake surface temperature estimates in lakes with variable characteristics and a variety of thermal spatial features, and longterm patterns within the study sites could be studied with NOAA AVHRR data despite the relatively coarse spatial resolution of the sensor. Restricting factors to the latter were the size and shape of lakes and the frequency of cloud cover. By contrast, the development of a universal Terra/Aqua MODIS algorithm for the estimation of chlorophyll a and Secchi disk depth in variable lakes was more challenging due to the optical complexity of Case II waters. Terra/Aqua MODIS data showed a potential, but the use of a different technique (e.g. multivariate regression or neural networks) and/or a different sensor (e.g. Envisat MERIS) could potentially improve the predictive accuracy of the algorithms.
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Avaliação da Influência térmica de um jardim vertical de tipologia parede viva contínua /Cruciol-Barbosa, Murilo January 2019 (has links)
Orientador: Maria Solange Gurgel de Castro Fontes / Resumo: O jardim vertical é todo sistema que permite o crescimento e o desenvolvimento da vegetação em superfícies verticalizadas. A parede viva é o tipo de jardim vertical que demanda maior tecnologia de produção e instalação e o seu modelo “parede viva contínua” é constituída por camadas (perfis metálicos, placas estruturantes, feltro, substrato e vegetação) que junto com uma cavidade de ar existente entre o jardim e a edificação funciona como uma proteção contra radiação solar incidente. A influência térmica da parede viva ocorre pela ação de quatro mecanismos que atuam em conjunto: sombreamento, isolamento térmico, barreira de vento e resfriamento evapotranspirativo. O mecanismo de sombreamento ocorre pela ação do sistema de jardim vertical que sombreia a superfície da parede e impede a incidência solar direta, sendo um dos mais importantes na influência térmica do jardim. Além disso, por meio do mecanismo evapotranspirativo, o jardim também influencia o microclima do seu entorno imediato. Assim, o presente projeto objetivou identificar o impacto de um jardim vertical de tipologia “parede viva contínua” na redução das temperaturas superficiais de uma parede e nos microclimas do seu entorno imediato (temperatura do ar, umidade absoluta e temperatura radiante média), em diferentes condições de tempo. Para isso, foi construída um jardim experimental, com delimitação de uma parcela controle. Os resultados mostraram influência significativa do jardim sobre as temperaturas superficiais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The vertical garden is any system that allows the growth and development of vegetation on vertical surfaces. The living wall is the typology of vertical garden that demands the most production and installation technology and its “continuous living wall” model consists of layers (metal profiles, structural plates, felt, substrate and vegetation) that together with an air cavity between the garden and the building acts as a protection against solar radiation. The thermal influence of the living wall occurs through the action of four mechanisms that act together: shading, thermal insulation, wind barrier and evapotranspiration cooling. The shading mechanism occurs by the action of the vertical garden system that shades the wall surface and prevents direct sunlight, being one of the most important in the thermal influence of the vertical garden. In addition, through the evapotranspiration mechanism, the vertical garden also influences the microclimate of its immediate surroundings. Thus, the present project aimed to identify the impact of a vertical garden of “continuous living wall” typology in the reduction of the surface temperatures of a wall and in the microclimates of its immediate surroundings (air temperature, absolute humidity and average radiant temperature), in different weather conditions. For this, an experimental garden was built, with delimitation of a control plot. The results showed a significant influence of the vertical garden on the surface temperatures and th... (Complete abstract click electronic access below) / Mestre
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