The Nepalese Himalaya, one of the most active regions within the Himalayan Mountain belt, is characterized by a thick succession of Miocene age Siwalik sedimentary rocks deposited at its foreland basin. To date, much of its tectonic evolution, including exhumation in the Nepalese Siwalik, is poorly understood. This study of a quantitative analysis of the bedrock river parameters should provide crucial information regarding tectonic activities in the area. The study investigated geomorphic parameters of river longitudinal profiles from 54 watersheds within the Siwalik section of the Nepalese Himalaya, for the first time. A total of 140 bedrock rivers from these watersheds were selected using stream power-law function and 30-meter resolution ASTER DEM. The quantitative data from the river longitudinal profiles were integrated with published exhumation ages. Results of this study show, first, a presence of major and minor knickpoints, with a total of 305 knickpoints identified, of which 180 were major knickpoints and the rest were minor knickpoints. Further classifications of knickpoints were based on structures (lineaments extracted from SRTM DEM), lithology, and possible uplift. Second, the Normalized Steepness index (ksn) values exhibited a range from 5.3 to 140.6. Third, the concavity index of streams in the study area ranged from as low as -12.1 to as high as 31.1 and the values were consistently higher upstream of the knickpoints. Finally, integration of the river profile data with the published exhumation ages show that the regions with a high ksn value correspond to the regions with higher incision and, therefore, are likely to have high uplift. The presence of a break in ksn in the eastern section of the study area suggests that the incision is likely accelerated by Main Frontal Thrust (MFT) movements. Erosion of the thrust sheet could have influenced the rapid uplift of the Siwalik due to isostatic processes. Thus, the timing of the source-region exhumation and its rate suggests that MFT-related tectonics, and/or climate processes, likely influenced the landscape evolution of the study area. The results of this study should help in comprehending the neo-tectonic deformation of the Nepalese Himalaya.

This research assesses the accuracy of SRTM and AIRSAR DEMs acquired over the mountainous-hillands of Cameron Highlands with DEMs generated from Digital Aerial Photograph (DAP) with a fine (2 m) spatial resolution and height resolution of about 0.5 m. The ground control points used for generating stereo models from the DAP were acquired during field work using GPS which achieved accuracy better than 2 cm in most cases. To overcome the difficulty of overlaying the DEMs with the DAP DEM as no features can be easily identified on both the images, therefore a technique of using transects and contours generated from the DEMs were used to correct the horizontal displacement. For AIRSAR DEM, comparing the accompanying AIRSAR composite images was also employed. These then allowed an analysis of the height accuracy to be undertaken. The height of both the AIRSAR and SRTM DEMs were also corrected by applying Linear Regression Models. These models were produced by comparing pixels obtained from points, profiles and an area. Once again the corrected DEMs were assessed. Finally the extracted profiles and contours from the corrected SRTM and AIRSAR were compared with the reference DEM. From the comparisons, the horizontal errors were found to be about one and the half pixels (138.72 m: for SRTM) to the east and 1 pixel (10 m: for AIRSAR) to the south. The SD of height differences of the SRTM and AIRSAR DEMs using 90% data were 9.2 m and 5.2 m with profiles comparison; 10.4 m and 5.4 m with area comparison; 10.8 m and 2.4 m with GPS GCPs comparison respectively. From the three comparisons, the means of height differences are 5.2 m, 6.1 m and 15.2 m for SRTM and 8.1 m, 8.3 m and 7.9 m for AIRSAR DEM. The results suggest there is height offset in the AIRSAR DEM. When both heights of DEMs were corrected, the generated contours are close to each other and to reference contours. Using contour colours images and height modelling, the corrected DEM was found to have the potential to detect areas that prone to flash floods and mudslides.

De l’observation microscopique d’une lame mince à l’observation mégascopique d’une province volcano-plutonique par télédétection (SRTM, Landsat), ce travail s’intéresse aux méthodes de comptage, aux traitements statistique et fractale des tailles, formes, orientations et distributions spatiales ainsi qu’à l’interprétation pétrogénétique et/ou géodynamique de différents marqueurs géologiques (cristaux, linéaments, cônes volcaniques…) associés au volcano-plutonisme phanérozoïque d’Afrique équatoriale (Ligne du Cameroun et régions voisines). L’analyse à l’échelle microscopique de la distribution de taille de grains et des textures de roches volcaniques et mantelliques (laves et enclaves provenant de l’île de Bioko, golfe de Guinée) a permis de mettre en évidence l’importance d’une quantification objective des paramètres de taille et des relations entre les phases minérales. Après avoir appliqué et discuté les résultats obtenus par les méthodes dites de « distribution de tailles de grains » ou CSD (Crystal Size Distribution), les relations spatiales entre les cristaux et donc les textures ont été étudiées par analyse fractale classique puis grâce à l’entropie de Shannon, dont il s’agit de la première application 2D. La généralisation de ces méthodes de comptage à des objets géologiques de plus grande taille (linéaments, cônes volcaniques…) par le biais des images satellites (Landsat) et modèles numériques de terrain (MNT) issus des données SRTM, a permis d’aborder de manière objective, sur un nombre suffisant de mesures, la morphostructure de la région étudiée. L’ensemble des données morpho-structurales, soit 15.171 linéaments, 8.092 cônes volcaniques ou complexes annulaires, d’une vaste zone de plus de 2.700.000 km2 autour du golfe de Guinée, ont permis d’élaborer plusieurs modèles structuraux locaux qui, synthétisés dans une vue spatio-temporelle complète depuis le Carbonifère jusqu’à l’actuel, ont permis de redéfinir l’évolution géodynamique de la région. Cette zone mobile complexe, pincée entre le craton congolais et le craton ouest-africain, est caractérisée par un soubassement précambrien, réactivé lors de la mise en place des grands bassins sédimentaires et ensembles magmatiques phanérozoiques. Contrairement à un modèle unique, souvent invoqué, l’évolution géologique régionale se présente comme une suite de régimes transcurrents dextres se déplaçant spatialement autour des directions N80 au Jurassique, N120 au Crétacé et N30 du Paléogène à l’actuel. L’intégration des nombreuses données géochimiques et isotopiques de la littérature aux modèles géodynamiques de ce travail oblige à globaliser le magmatisme cénozoïque à l’échelle de l’Afrique équatoriale dans son ensemble qui se présente alors comme un « ensemble » magmatique cohérent.

This research assesses the accuracy of SRTM and AIRSAR DEMs acquired over the mountainous-hillands of Cameron Highlands with DEMs generated from Digital Aerial Photograph (DAP) with a fine (2 m) spatial resolution and height resolution of about 0.5 m. The ground control points used for generating stereo models from the DAP were acquired during field work using GPS which achieved accuracy better than 2 cm in most cases. To overcome the difficulty of overlaying the DEMs with the DAP DEM as no features can be easily identified on both the images, therefore a technique of using transects and contours generated from the DEMs were used to correct the horizontal displacement. For AIRSAR DEM, comparing the accompanying AIRSAR composite images was also employed. These then allowed an analysis of the height accuracy to be undertaken. The height of both the AIRSAR and SRTM DEMs were also corrected by applying Linear Regression Models. These models were produced by comparing pixels obtained from points, profiles and an area. Once again the corrected DEMs were assessed. Finally the extracted profiles and contours from the corrected SRTM and AIRSAR were compared with the reference DEM. From the comparisons, the horizontal errors were found to be about one and the half pixels (138.72 m: for SRTM) to the east and 1 pixel (10 m: for AIRSAR) to the south. The SD of height differences of the SRTM and AIRSAR DEMs using 90% data were 9.2 m and 5.2 m with profiles comparison; 10.4 m and 5.4 m with area comparison; 10.8 m and 2.4 m with GPS GCPs comparison respectively. From the three comparisons, the means of height differences are 5.2 m, 6.1 m and 15.2 m for SRTM and 8.1 m, 8.3 m and 7.9 m for AIRSAR DEM. The results suggest there is height offset in the AIRSAR DEM. When both heights of DEMs were corrected, the generated contours are close to each other and to reference contours. Using contour colours images and height modelling, the corrected DEM was found to have the potential to detect areas that prone to flash floods and mudslides.

Mountain glaciers are expected to be the greatest contributor to sea level rise over the next century. Glaciers provide a good indicator of global climate and how to monitor their change is an increasingly important issue for climate science and for sea level rise forecasts. However, there has been little direct measurement of glacier volume change in New Zealand. This study explores the use of remotely sensed data for measuring glacier volume change from 1965 to 2006. Digital photogrammetric methods were used to extract topographic data of the Tasman Glacier from aerial photography and ASTER imagery for the years 1965, 1986, 2002 and 2006. SRTM C band data from 2000 were also analysed. Data were compared to an existing digital elvation model produced from the New Zealand Digital Topographic Database to test for their reliability. Using regression analysis, the data were filtered and points representing rock were used to correct points on the glacier ice for vertical bias. The quality of the data extracted from the aerial photography was good on rock and debris covered ice, but poor on snow. The data extracted from ASTER was much more reliable on snow in the upper glacier than the aerial photography, but was very poor in the lower debris covered region of the glacier. While the quality of the SRTM data is very high, there is a second order distortion present in the data that is evident over elevation differences. However, the overall mean difference of the SRTM rock from TOPODATA is close to zero. An overall trend could be seen in the data between dates. However, the 2006 ASTER data proved unreliable on the debris covered section of the glacier. Total volume change is therefore calculated for the period between 1965 and 2002. The data show a loss of 3:4km³ or 0:092km³ per year, an estimated 6% of the total ice in New Zealand. This is compared to estimates using the annual end of summer snowline survey between 1977 and 2005 of 1:78 km³, or 0:064km³ per year. The spatial resolution of ASTER makes high temporal resolution monitoring of volume change unlikely for the New Zealand glaciers. The infrequency of aerial photography, the high cost and vast time involved in extracting good quality elevation data from aerial photography makes it impractical for monitoring glacier volume change remotely. However, SRTM and other radar sensors may provide a better solution, as the data do not rely heavily on user processing.

O objetivo deste trabalho foi a geração e avaliação de ortoimagens ALOS/PRISM, utilizandose para isso MDEs (Modelos Digitais de Elevação) obtidos através das diferentes combinações de visadas desse sensor de uma imagem com nível de processamento 1B1. Na primeira etapa foram gerados os MDEs a partir das combinações das três visadas, utilizando-se para isso pontos de controle obtidos através de levantamento de campo, onde foram testados a quantidade mínima necessária de pontos de controle para geração de MDE e outros parâmetros tais como nível de processamento, tamanho de janela, entre outros. Na etapa seguinte, comparou-se o resultado da extração com os Modelos Digitais de Elevação do ASTER (GDEM) e o SRTM (Shuttle Radar Topographic Mission), este gerado a partir do Projeto TOPODATA do INPE (Instituto Nacional de Pesquisas Espaciais). Na etapa final avaliaram-se os MDEs com os pontos de checagem. Através de análises estatísticas selecionaram-se os melhores MDEs para ortorretificação. Os resultados demonstraram que, para este caso específico, todos os MDES da combinação de visada Backward – Foward (gerados a partir de 6 pontos de controle) seriam aprovados por apresentarem os menores valores de RMS (entre 2,94 e 3m) e que, ao se utilizar outros MDEs oriundos de outras combinações, as ortoimagens obtidas também atendem ao Padrão de Exatidão Cartográfica (PEC) Classe A para escala 1:25.000, bem como as ortoimagens geradas com os Modelos de Elevação Globais SRTM e GDEM. A área de estudo escolhida foi uma região rural do município de São Gabriel – RS, que possui relevo com média altimétrica de 160m, podendo ser considerado plano, o que justifica o bom desempenho do SRTM em conjunto com os MDEs gerados a partir do PRISM. / The aim of this work was the generation and evaluation of orthoimages ALOS / PRISM, using the MDEs (Digital Elevation Models) obtained using different combinations of sensor views of an image with 1B1 processing level. In the first step the MDEs were created from combinations of three views, using for it the ground control points obtained by field survey, where the minimum amount necessary of control points for DEM generation and other parameters as processing level, size of the windows, among others were tested. In the further step, the result of extraction was compared to Digital Elevation Models from ASTER (GDEM) and SRTM (Shuttle Radar Topographic Mission), this one generated from the Project TOPODATA from INPE (National Institute for Space Research). In the final step, the MDEs were evaluated with the checkpoints. Through statistical analysis the best MDEs were selected for orthorectification. The results showed that, for this specific case, all MDEs combination of Backward - Foward (generated from 6 control points) would be approved by submitting the lowest values of RMS (between 2.94 and 3 m) and, when using other MDEs from another combinations, obtained orthoimages also satisfies the Cartographic Accuracy Standard (PEC) for Class A 1:25,000 scale, as the orthoimages generated from the SRTM and GDEM. The chosen study area was a rural region of São Gabriel - RS, which has average altitude of 160 m, can be considered plane, which explains the good performance of the SRTM in conjunction with the MDEs generated from PRISM.

Com o surgimento de novos métodos de extração de dados altimétricos no mercado de geotecnologias a escolha da melhor técnica é um problema que preocupa a maioria dos usuários. Como nenhum dado está isento de erros faz-se necessário propor método que faça uso dessa diversidade de informações minimizando-se o erro. A Colocação por Mínimos Quadrados é uma técnica que permite a integração de dados diferentes em tipo e precisão. Assim, a presente dissertação teve como objetivo a determinação e avaliação de um novo Modelo Digital de Elevação, denominado MDE Híbrido, a partir de dados altimétricos obtidos através de diferentes técnicas: fotogrametria (curvas de nível extraídas de carta 1:50.000), estereoscopia em imagens de um sensor orbital (ASTER) e interferometria de radar (SRTM). Foram selecionadas três áreas no município de Porto Alegre/RS, que apresentam diferentes tipos de relevo: plano, misto e acidentado. Nessas áreas foram obtidos os MDEs a partir de curvas de nível, imagens ASTER e do SRTM com resoluções de 30m, 15m e 90m respectivamente. Uma avaliação pontual foi realizada nos três dados onde pode-se observar que para cada área de estudo um diferente dado apresentou menor Erro Médio Quadrático. Estes três dados foram então integrados utilizando-se a Colocação por Mínimos Quadrados e resolução de 15m. Após avaliação, o MDE Híbrido na Área Plana apresentou acurácia altimétrica igual a 3,493m e na Área Mista o valor de 4,763m o que atende aos requisitos da Classe A do PEC (Padrão de Exatidão Cartográfico) na escala 1:25.000. Já na Área Acidentada o valor encontrado foi de 8,66m atendendo os requisitos da Classe A do PEC na escala 1:50.000. Os resultados práticos alcançados nesta pesquisa mostraram que os dados altimétricos com diferentes resoluções espaciais podem ser integrados, desde que se tenha conhecimento das suas precisões. A resolução espacial de um determinado dado não está relacionada com a precisão deste dado. / With the appearance of new methods of altimetric data extraction, the choice for the best technique is a problem that concerns the majority of users. As no data is error free, it is necessary to propose a methodology that may use this diversity of information as well as minimize errors which arise from each data. The Least-Squares Collocation (CMQ) is a technique that allows the integration of different data according to type and precision. Thus, this paper aimed at determining and evaluating a new Digital Elevation Model called Hybrid MDE, which was obtained through the integration of data from different techniques: Photogrammetry (level curves extracted from maps, Stereoscopy (ASTER) and Interferometry (SRTM). To evaluate the efficiency of this methodology, we selected three areas in the city of Porto Alegre/RS, which showed different types of relief: plain, mixed and rough. In these areas, the MDEs were generated from level curves and ASTER images, which had a resolution of 30 m and 15m respectively; we also included the SRTM data, which show a resolution of 90 m. These three data were then integrated, using the CMQ, and determining a new model with a final resolution of 15 m, which was called Hybrid MDE. Lastly, we realized an evaluation, in which the Hybrid MDE in the Plain Area showed an altimetric accuracy equal to 3,493 m and in the Mixed Area 4, 763, which follows the Class A requisites of the Standard of Cartographic Exactness (PEC) in the scale of 1:25.000. In the Rough Area, the value found was 8, 66 m , following the Class A requisites for PEC in the scale of 1:50.000. The practical results reached in this research show that altimetric data with different spatial resolutions may be integrated, as long as we are aware of its precision.

O objetivo deste trabalho foi o analisar o impacto da resolução dos conjuntos de dados topográficos nas simulações das concentrações de dióxido de enxofre (SO2) emitido por uma fonte localizada no Sul do Brasil. Para isso foram realizadas duas simulações aplicando o modelo regional Weather Research and Forecasting acoplado com a química (WRF/Chem), configurado com duas representações do terreno de diferentes resoluções espaciais. Foram utilizados os dados padrão do modelo com melhor resolução, Global 30 Arc-Second Elevation (GTOPO), com aproximadamente 1 km, e inserido no bancos de dados do modelo as informações de terreno em alta-resolução do Radar Shuttle Topography Mission (SRTM) (30 metros). Para as emissões antrópicas do modelo foi elaborado um programa capaz inserir os volumes do poluente SO2 de forma horária expelidos pela chaminé, de acordo com as taxas de emissão medidos diretamente na fonte. O programa representou a emissão do poluente no ponto de grade correspondente a localização e a altura acima da superfície da chaminé da fonte. As simulações foram configuradas com os seguintes esquemas de parametrização: para microfísica de nuvens foi utilizado o Goddard Cumulus Ensemble; os esquemas de radiação de onda longa e curta foram o Goddard e o Rapid Radiative Transfer Model para modelos de circulação geral da atmosfera (MCGA); para a parametrização de cumulus o esquema utilizado foi o Grell 3D Ensemble Scheme; e para os esquemas de camada superficial e camada limite planetária foram utilizados os da teoria da similaridade do Fifth-Generation National Center for Atmospheric Research/Penn State Mesoscale Model (MM5) e o Yonsey University, respectivamente. A escolha desta combinação de esquemas foi definida a partir de um estudo inicial da sensibilidade do modelo à mudança das parametrizações. Os resultados dos experimentos numéricos alterando a topografia foram validados a partir dos dados de monitoramento das estações meteorológica e da qualidade do ar pertencentes à empresa responsável pelo empreendimento associado à fonte. Foi observado que as simulações com os dados SRTM expressaram o terreno da região de estudo mais próximo à realidade, representando o aspecto heterogêneo do relevo, ressaltando os picos e os vales. Os resultados das validações meteorológicas utilizando os dados topográficos indicaram melhoras nas simulações das variáveis meteorológicas: temperatura, umidade relativa, velocidade do vento e precipitação. Os experimentos com os dados topográficos GTOPO e SRTM no modelo WRF/Chem, configurado com as emissões horárias da fonte de Candiota, reproduziram o comportamento dos ventos para transporte de SO2 até as estações de monitoramento conforme os dados observados. Porém foram identificados padrões diferentes na representação das concentrações do poluente entre as duas simulações do modelo, associados aos escoamentos dos ventos representados pelos experimentos. A resolução da topografia afetou na simulação de SO2 devido ao aumento da forçante superficial induzida pelo terreno. Este aumento na forçante, influenciou a advecção da pluma de SO2, resultando em diferentes padrões das concentrações de SO2 no ponto de grade correspondente às estações de monitoramento. Contudo, os resultados das simulações das concentrações de SO2, tanto de forma horária quanto na abordagem das médias diárias, não indicaram uma relação linear entre a utilização de dados em alta resolução e a melhora na representação do SO2 pelo modelo WRF/Chem. / The objective of this work was to analyze the impact of the higher resolution topographic data sets in the simulations of the Sulfur dioxide (SO2) concentrations emitted by a source located Southern Brazil. Two simulations were performed applying the Weather Research and Forecasting model coupled with Chemistry – WRF/Chem, configured with two representations of the terrain with different spatial resolutions. The standard data of the model with the best resolution (approximately 1 km), Global 30 Arc-Second Elevation (GTOPO), and was inserted in the model databases the high-resolution (30 meters) terrain information of the Radar Shuttle Topography Mission (SRTM). For the anthropic emissions of the model, a program was developed capable of inserting the hourly SO2 pollutant volumes expelled by the chimney, according to the emission rates measured directly at the source. The program inserted these emissions into the grid point corresponding to the location and height above the surface of the emission source. The simulations were configured with the following parameterization schemes: for cloud microphysics Goddard Cumulus Ensemble; for the long and short wave radiation treatment it was used the Goddard and the Rapid Radiative Transfer Model for general circulation models; for the cumulus parameterization the scheme it was used the Grell 3D Ensemble Scheme; and for the surface layer and planetary boundary layer schemes, the similarity theory of the Fifth-Generation National Center for Atmospheric Research/Penn State Mesoscale Model (MM5) and the Yonsey University, respectively. The choice of this combination of schemes was defined from an initial study of the sensitivity of the model to the change of parametrizations. The results of the numerical experiments altering the topography were validated from the monitoring data of the meteorological stations and the air quality belonging to the company responsible for the enterprise associated to the source. It was observed that the simulations with the SRTM data expressed the terrain of the region of study closest to reality, representing the heterogeneous aspect of the terrain, highlighting the peaks and valleys. The results of the meteorological validations using the new topographic data indicated an improvement in the simulations of the meteorological variables: temperature, relative humidity, wind speed and precipitation. The experiments with the GTOPO and SRTM topographic data in WRF/Chem model, configured with the hourly emissions of the Candiota source, reproduced the winds behavior that transported the SO2 to the monitoring stations according to the observed data. However, different patterns were identified in the pollutant concentrations between the two simulations of the model, associated to the wind flows represented by the experiments. The topography resolution affected in the simulation of SO2 due to the increase of the surface forcing induced by the terrain. This increase in the forcing influenced the advection of the SO2 plume, resulting in different patterns of SO2 concentrations at the grid point corresponding to the monitoring stations. However, the results of simulations of SO2 concentrations, both hourly and in the approach of daily averages, did not indicate a linear relationship between the use of high resolution data and the improvement in the representation of SO2 by WRF/Chem model.

Com o surgimento de novos métodos de extração de dados altimétricos no mercado de geotecnologias a escolha da melhor técnica é um problema que preocupa a maioria dos usuários. Como nenhum dado está isento de erros faz-se necessário propor método que faça uso dessa diversidade de informações minimizando-se o erro. A Colocação por Mínimos Quadrados é uma técnica que permite a integração de dados diferentes em tipo e precisão. Assim, a presente dissertação teve como objetivo a determinação e avaliação de um novo Modelo Digital de Elevação, denominado MDE Híbrido, a partir de dados altimétricos obtidos através de diferentes técnicas: fotogrametria (curvas de nível extraídas de carta 1:50.000), estereoscopia em imagens de um sensor orbital (ASTER) e interferometria de radar (SRTM). Foram selecionadas três áreas no município de Porto Alegre/RS, que apresentam diferentes tipos de relevo: plano, misto e acidentado. Nessas áreas foram obtidos os MDEs a partir de curvas de nível, imagens ASTER e do SRTM com resoluções de 30m, 15m e 90m respectivamente. Uma avaliação pontual foi realizada nos três dados onde pode-se observar que para cada área de estudo um diferente dado apresentou menor Erro Médio Quadrático. Estes três dados foram então integrados utilizando-se a Colocação por Mínimos Quadrados e resolução de 15m. Após avaliação, o MDE Híbrido na Área Plana apresentou acurácia altimétrica igual a 3,493m e na Área Mista o valor de 4,763m o que atende aos requisitos da Classe A do PEC (Padrão de Exatidão Cartográfico) na escala 1:25.000. Já na Área Acidentada o valor encontrado foi de 8,66m atendendo os requisitos da Classe A do PEC na escala 1:50.000. Os resultados práticos alcançados nesta pesquisa mostraram que os dados altimétricos com diferentes resoluções espaciais podem ser integrados, desde que se tenha conhecimento das suas precisões. A resolução espacial de um determinado dado não está relacionada com a precisão deste dado. / With the appearance of new methods of altimetric data extraction, the choice for the best technique is a problem that concerns the majority of users. As no data is error free, it is necessary to propose a methodology that may use this diversity of information as well as minimize errors which arise from each data. The Least-Squares Collocation (CMQ) is a technique that allows the integration of different data according to type and precision. Thus, this paper aimed at determining and evaluating a new Digital Elevation Model called Hybrid MDE, which was obtained through the integration of data from different techniques: Photogrammetry (level curves extracted from maps, Stereoscopy (ASTER) and Interferometry (SRTM). To evaluate the efficiency of this methodology, we selected three areas in the city of Porto Alegre/RS, which showed different types of relief: plain, mixed and rough. In these areas, the MDEs were generated from level curves and ASTER images, which had a resolution of 30 m and 15m respectively; we also included the SRTM data, which show a resolution of 90 m. These three data were then integrated, using the CMQ, and determining a new model with a final resolution of 15 m, which was called Hybrid MDE. Lastly, we realized an evaluation, in which the Hybrid MDE in the Plain Area showed an altimetric accuracy equal to 3,493 m and in the Mixed Area 4, 763, which follows the Class A requisites of the Standard of Cartographic Exactness (PEC) in the scale of 1:25.000. In the Rough Area, the value found was 8, 66 m , following the Class A requisites for PEC in the scale of 1:50.000. The practical results reached in this research show that altimetric data with different spatial resolutions may be integrated, as long as we are aware of its precision.

O objetivo deste trabalho foi o analisar o impacto da resolução dos conjuntos de dados topográficos nas simulações das concentrações de dióxido de enxofre (SO2) emitido por uma fonte localizada no Sul do Brasil. Para isso foram realizadas duas simulações aplicando o modelo regional Weather Research and Forecasting acoplado com a química (WRF/Chem), configurado com duas representações do terreno de diferentes resoluções espaciais. Foram utilizados os dados padrão do modelo com melhor resolução, Global 30 Arc-Second Elevation (GTOPO), com aproximadamente 1 km, e inserido no bancos de dados do modelo as informações de terreno em alta-resolução do Radar Shuttle Topography Mission (SRTM) (30 metros). Para as emissões antrópicas do modelo foi elaborado um programa capaz inserir os volumes do poluente SO2 de forma horária expelidos pela chaminé, de acordo com as taxas de emissão medidos diretamente na fonte. O programa representou a emissão do poluente no ponto de grade correspondente a localização e a altura acima da superfície da chaminé da fonte. As simulações foram configuradas com os seguintes esquemas de parametrização: para microfísica de nuvens foi utilizado o Goddard Cumulus Ensemble; os esquemas de radiação de onda longa e curta foram o Goddard e o Rapid Radiative Transfer Model para modelos de circulação geral da atmosfera (MCGA); para a parametrização de cumulus o esquema utilizado foi o Grell 3D Ensemble Scheme; e para os esquemas de camada superficial e camada limite planetária foram utilizados os da teoria da similaridade do Fifth-Generation National Center for Atmospheric Research/Penn State Mesoscale Model (MM5) e o Yonsey University, respectivamente. A escolha desta combinação de esquemas foi definida a partir de um estudo inicial da sensibilidade do modelo à mudança das parametrizações. Os resultados dos experimentos numéricos alterando a topografia foram validados a partir dos dados de monitoramento das estações meteorológica e da qualidade do ar pertencentes à empresa responsável pelo empreendimento associado à fonte. Foi observado que as simulações com os dados SRTM expressaram o terreno da região de estudo mais próximo à realidade, representando o aspecto heterogêneo do relevo, ressaltando os picos e os vales. Os resultados das validações meteorológicas utilizando os dados topográficos indicaram melhoras nas simulações das variáveis meteorológicas: temperatura, umidade relativa, velocidade do vento e precipitação. Os experimentos com os dados topográficos GTOPO e SRTM no modelo WRF/Chem, configurado com as emissões horárias da fonte de Candiota, reproduziram o comportamento dos ventos para transporte de SO2 até as estações de monitoramento conforme os dados observados. Porém foram identificados padrões diferentes na representação das concentrações do poluente entre as duas simulações do modelo, associados aos escoamentos dos ventos representados pelos experimentos. A resolução da topografia afetou na simulação de SO2 devido ao aumento da forçante superficial induzida pelo terreno. Este aumento na forçante, influenciou a advecção da pluma de SO2, resultando em diferentes padrões das concentrações de SO2 no ponto de grade correspondente às estações de monitoramento. Contudo, os resultados das simulações das concentrações de SO2, tanto de forma horária quanto na abordagem das médias diárias, não indicaram uma relação linear entre a utilização de dados em alta resolução e a melhora na representação do SO2 pelo modelo WRF/Chem. / The objective of this work was to analyze the impact of the higher resolution topographic data sets in the simulations of the Sulfur dioxide (SO2) concentrations emitted by a source located Southern Brazil. Two simulations were performed applying the Weather Research and Forecasting model coupled with Chemistry – WRF/Chem, configured with two representations of the terrain with different spatial resolutions. The standard data of the model with the best resolution (approximately 1 km), Global 30 Arc-Second Elevation (GTOPO), and was inserted in the model databases the high-resolution (30 meters) terrain information of the Radar Shuttle Topography Mission (SRTM). For the anthropic emissions of the model, a program was developed capable of inserting the hourly SO2 pollutant volumes expelled by the chimney, according to the emission rates measured directly at the source. The program inserted these emissions into the grid point corresponding to the location and height above the surface of the emission source. The simulations were configured with the following parameterization schemes: for cloud microphysics Goddard Cumulus Ensemble; for the long and short wave radiation treatment it was used the Goddard and the Rapid Radiative Transfer Model for general circulation models; for the cumulus parameterization the scheme it was used the Grell 3D Ensemble Scheme; and for the surface layer and planetary boundary layer schemes, the similarity theory of the Fifth-Generation National Center for Atmospheric Research/Penn State Mesoscale Model (MM5) and the Yonsey University, respectively. The choice of this combination of schemes was defined from an initial study of the sensitivity of the model to the change of parametrizations. The results of the numerical experiments altering the topography were validated from the monitoring data of the meteorological stations and the air quality belonging to the company responsible for the enterprise associated to the source. It was observed that the simulations with the SRTM data expressed the terrain of the region of study closest to reality, representing the heterogeneous aspect of the terrain, highlighting the peaks and valleys. The results of the meteorological validations using the new topographic data indicated an improvement in the simulations of the meteorological variables: temperature, relative humidity, wind speed and precipitation. The experiments with the GTOPO and SRTM topographic data in WRF/Chem model, configured with the hourly emissions of the Candiota source, reproduced the winds behavior that transported the SO2 to the monitoring stations according to the observed data. However, different patterns were identified in the pollutant concentrations between the two simulations of the model, associated to the wind flows represented by the experiments. The topography resolution affected in the simulation of SO2 due to the increase of the surface forcing induced by the terrain. This increase in the forcing influenced the advection of the SO2 plume, resulting in different patterns of SO2 concentrations at the grid point corresponding to the monitoring stations. However, the results of simulations of SO2 concentrations, both hourly and in the approach of daily averages, did not indicate a linear relationship between the use of high resolution data and the improvement in the representation of SO2 by WRF/Chem model.