Este trabalho apresenta a solução da equação da difusão-advecção bidimensional estacionária para simular a dispersão de poluentes na Camada Limite Planetária. A solução é obtida através do método ADMM (Analytical Dispersion Multilayer Model) e da técnica de inversão numérica utilizando o algoritmo de Fixed Talbot. A validação da solução é comprovada, mediante os parâmetros estatísticos, através do confrontamento das concentrações calculadas a partir do modelo com as obtidas experimentalmente pelo experimento de Prairie Grass. Para a determinação das concentrações utiliza-se o perfil do vento segundo o modelo de similaridade de Monin-Obukhov e os parâmetros de turbulência com dependência da distância longitudinal da fonte e da altura vertical, considerando a componente vertical do espectro Euleriano e de acordo com o modelo sugerido por Hɸjstrup que divide os espectros em alta e baixa frequência. Para efeito comparativo utiliza-se um coeficiente de difusão para grandes tempos de difusão. Os melhores resultados foram alcançados com a utilização dos coeficientes de difusão considerando a distância longitudinal da fonte e a altura vertical.

This work aims to assess the Weather and Research Forecasting (WRF) model wind simulation and wind energy production estimates sensitivity to different planetary boundary layer parameterization schemes. Five WRF simulations considering different sets of planetary boundary layer (PBL) and surface layer (SL) parameterization schemes were performed, and their results compared to measured wind data collected at five offshore buoys and thirteen onshore wind measuring stations located in the Iberian Peninsula. The objective is to determine which of these model configurations produces wind simulations and wind energy productions estimates closest to measured wind data and wind energy production estimates derived from measurements, aiming to provide guidelines for onshore and offshore wind energy assessment studies focused on areas where measured wind data is not available and numerical modelling is necessary. This work focuses on the Iberian Peninsula, an area with intensive wind energy penetration due to its favourable wind conditions, which combined with its large coastline makes this area a promising one for the future installation of offshore wind farms.The results presented in this work show that, although no major differences are seen among the simulations in terms of wind speed and direction simulation accuracy, in terms of wind energy production estimates the differences are not negligible due to the high sensitivity of the wind energy production to the wind simulation accuracy. The PBL-SL parameterization set composed by the schemes ACM2-PX is the one with the lowest errors when compared to observed wind data, when considering all onshore and offshore sites together. The ACM2 PBL scheme combines features of local and non-local closure schemes and the PX LSM scheme provides a better parameterization of the surface meteorology, which proved to be important in the model performance. However, for offshore sites the PBL-SL parameterizations QNSE-QNSE produced the best wind energy production estimates.Due to the close dependence of each PBL and SL scheme performance on the surrounding synoptic conditions and atmospheric stability, it is expected that for different geographical areas and/or temporal periods these schemes may show different results. However, the fact that this study includes one complete year of simulation for a considerably wide geographical area, including the different synoptic conditions that typically occur in a annual cycle, provides a solid base of confidence that the conclusions drawn from this work may be applied to other periods and/or geographical areas.

The central theme of this study is the numerical simulation of fog events on the north coast of Portugal. The main objective is the identification of the aspects that offer the most scope for improve the simulation of this phenomenon using the atmospheric WRF model. Through a review of the scientific literature related to this topic, two formation processes were identified that seem predominant in areas with meteorological characteristics similar to those of the Portuguese coast: the advection of humid air over cold coastal waters and the propagation towards the surface of low clouds. One of the most important parts of the study is the comparison of the impact of several physical schemes in the simulation of different fog events. Within the different parameterization categories analyzed, the radiation and the planetary boundary layer are the ones that produce the biggest variations in the results. In contrast, the different parameterizations of the microphysics used did not provide significant differences. The performance of a sensitivity test of the SST, which consists in introducing a negative artificial anomaly in the SSTs near the west coast of the Iberian Peninsula, showed that the SST errors will have a much smaller impact than the coice of the physical parametrizations in the simulation of the fog event. In addition, the simulations executed with the SSTs obtained with the oceanic model ROMS reaffirm this hypothesis. Finally, when the dominant formation process of each event was identified, a connection between the formation process and the parameterization that produces better results of each event was observed

Existe uma variedade de modelos de dispersão de poluentes, em geral, os modelos gaussianos são usados em todo o mundo por agências ambientais com intuito de regulação. O modelo CALPUFF é um deles. Neste estudo, _e avaliada a influência de escalas de tempo de descorrelação no sistema de modelagem CALPUFF, sob condições atmosféricas neutras. Para fazer isso uma nova parametrização das escalas de tempo descorrelação é proposta. Uma distribuição espectral de um perfil de velocidade euleriana e uma for- mutação da evolução das escalas temporais de descorrelação Lagrangiana são utilizadas como os mecanismos forçantes na dispersão turbulenta, numa camada limite dominada pelo cisalhamento do vento. O desempenho do modelo foi estabelecido com a comparação das concentrações superficiais do experimento Over-Land Alongwind Dispersion. Emissões de fontes em linha foram avaliadas com o modelo CALPUFF com distintas formas de inicialização. Um segundo modelo também foi testado, normalmente utilizado para estudar e prever o impacto ambiental e validar parametrizações turbulentas. É o modelo estocástico de partículas Lagrangiano LAMBDA. Também neste estudo, os resultados do modelo LAMBDA e CALPUFF enfatizam a capacidade da nova derivação de escalas de tempo em representar o comportamento estocástico desconhecido do fenômeno da dispersão de poluentes.

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