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. / There exists a variety of pollution of dispersion models and in general, Gaussian models are used worldwide by environmental agencies in regulatory applications. The CALPUFF model is one of them. In this study, the in uence of decorrelation time scales in the CALPUFF modeling system under neutral conditions is evaluated. To do this a new parameterization of decorrelation time scales is proposed. A spectral distribution of an Eulerian velocity pro le and a formulation of the evolution of the Lagrangian decorrela- tion timescales are used as the forcing mechanisms (shear-dominated boundary layer) for the turbulent dispersion. The model performance was established by comparing ground- level concentrations with Over-Land Alongwind Dispersion experimental results. Line source emissions was evaluated using the CALPUFF model with different forms of the initialization. A second model was also tested, normally used to study and predict the environmental impact and validate turbulent parameterizations. Is the stochastic La- grangian dispersion model LAMBDA (Ferrero and Anfossi, 1998). Also in this study the model LAMBDA and CALPUFF results emphasized the ability of the new derivation of decorrelation time scales to represent the unknown stochastic behavior.

On January 29-30, 2008 a squall line of thunderstorms moved through the Ohio Valley resulting in four deaths and one injury. Such events highlight the importance of accurate forecasting for public safety. Mesoscale Modeling plays an important role in any forecast of a potential squall line. The focus of this study was to examine the performance of several parameterization scheme combinations in the Weather Research and Forecasting Model version three (WRF) as they related to this event. These examinations included cloud microphysics (WRF Single-Moment 3-class, 6-class, and Goddard), cumulus parameterization (Kain-Fritsch and Bets-Miller-Janjic) and planetary boundary layer schemes (Yonsei-University and Mellor-Yamada-Janjic). A total of 12 WRF simulations were conducted for all potential scheme combinations. Data from the WRF simulations for several locations in south central Kentucky were analyzed and compared using Kentucky Mesonet observations for four locations: Bowling Green, Russellville, Murray and Liberty, KY. A fine model resolution of 1 km was used over these locations. Coarser resolutions of 3 km and 9 km were used on the outer two domains, which encompassed the Ohio and Tennessee Valleys. The model simulation performance was assessed using established statistical measures for the above four locations and by visually comparing the North American Regional Reanalysis dataset (NARR) along with modeled simulations. The most satisfactory scheme combination was the WRF Single-Moment 3-class Microphysics scheme, Kain-Fritsch cumulus parameterization scheme and Yonsei University scheme for the planetary boundary layer. The planetary boundary layer schemes were noted to have the greatest influence in determining the most satisfactory model simulations. There was limited influence from different selections of microphysics and cumulus parameterization schemes. The preferred physics parameters from these simulations were then used in six additional simulations to analyze the affect different initialization data sets have with regards to model output. Data sets used in these simulations were the Final Operational Analysis global data, North American Regional Reanalysis (3 and 6 hour) and the North American Mesoscale Model at 1, 3 and 6 hour timesteps, for a total of six simulations. More timesteps or an increase in model resolution did not materially improve the model performance.

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. / There exists a variety of pollution of dispersion models and in general, Gaussian models are used worldwide by environmental agencies in regulatory applications. The CALPUFF model is one of them. In this study, the in uence of decorrelation time scales in the CALPUFF modeling system under neutral conditions is evaluated. To do this a new parameterization of decorrelation time scales is proposed. A spectral distribution of an Eulerian velocity pro le and a formulation of the evolution of the Lagrangian decorrela- tion timescales are used as the forcing mechanisms (shear-dominated boundary layer) for the turbulent dispersion. The model performance was established by comparing ground- level concentrations with Over-Land Alongwind Dispersion experimental results. Line source emissions was evaluated using the CALPUFF model with different forms of the initialization. A second model was also tested, normally used to study and predict the environmental impact and validate turbulent parameterizations. Is the stochastic La- grangian dispersion model LAMBDA (Ferrero and Anfossi, 1998). Also in this study the model LAMBDA and CALPUFF results emphasized the ability of the new derivation of decorrelation time scales to represent the unknown stochastic behavior.

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. / There exists a variety of pollution of dispersion models and in general, Gaussian models are used worldwide by environmental agencies in regulatory applications. The CALPUFF model is one of them. In this study, the in uence of decorrelation time scales in the CALPUFF modeling system under neutral conditions is evaluated. To do this a new parameterization of decorrelation time scales is proposed. A spectral distribution of an Eulerian velocity pro le and a formulation of the evolution of the Lagrangian decorrela- tion timescales are used as the forcing mechanisms (shear-dominated boundary layer) for the turbulent dispersion. The model performance was established by comparing ground- level concentrations with Over-Land Alongwind Dispersion experimental results. Line source emissions was evaluated using the CALPUFF model with different forms of the initialization. A second model was also tested, normally used to study and predict the environmental impact and validate turbulent parameterizations. Is the stochastic La- grangian dispersion model LAMBDA (Ferrero and Anfossi, 1998). Also in this study the model LAMBDA and CALPUFF results emphasized the ability of the new derivation of decorrelation time scales to represent the unknown stochastic behavior.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-05-14T20:44:44Z No. of bitstreams: 1 WALÉRIA SOUZA FIGUEIRA – DISSERTAÇÃO (PPGMET) 2015.pdf: 2735921 bytes, checksum: c2ab85caa20115480b90d1325acfad13 (MD5) / Made available in DSpace on 2018-05-14T20:44:44Z (GMT). No. of bitstreams: 1 WALÉRIA SOUZA FIGUEIRA – DISSERTAÇÃO (PPGMET) 2015.pdf: 2735921 bytes, checksum: c2ab85caa20115480b90d1325acfad13 (MD5) Previous issue date: 2015-03-05 / CNPq / Este trabalho teve como objetivo estudar o efeito da remoção de umidade da camada limite planetária por cúmulos rasos. Para tal, esse efeito foi inserido no código do modelo BRAMS. Foram realizados dois experimentos: no primeiro experimento de controle (EXP_ORI), o modelo foi inicializado em sua forma original e no segundo (EXP_AJUST), o modelo foi integrado para as mesmas condições que o EXP_ORI, porém com o devido ajuste realizado no código do BRAMS. O modelo foi integrado para um período de 774 horas a partir da 00 UTC do dia 1° de janeiro até a 00 UTC do dia 1° de fevereiro de 2011. Para facilitar a análise quanto ao impacto desse ajuste no ciclo diário médio das variáveis termodinâmicas de superfície e da precipitação convectiva, foram feitas médias em duas áreas distintas de 1°x1°, uma área sobre superfície florestada (localizada no sul do Amazonas) e outra área sobre superfície desflorestada (localizada no norte da Bolívia). De forma geral, os resultados mostraram que houve diferenças notáveis no perfil termodinâmico da troposfera inferior devido à implementação do novo ajuste. As taxas de aquecimento e umedecimento, em ambas as áreas, tiveram picos as 09 e 09:30 horas local, embora o seu efeito líquido tenha se mostrado nas horas seguintes, o principal impacto ocorreu no início da tarde. O ciclo diário dos fluxos à superfície também foram sensíveis ao ajuste realizado no modelo. Já o comportamento e a quantidade da precipitação convectiva acumulada ao longo do dia foram melhorados no EXP_AJUST, principalmente na área desflorestada. / The objective of this work was to the effects of moisture removal from the planetary boundary layer by shallow cumulus. To reach this goal, this effect was implemented into the BRAMS model code. Two experiments were performed: in the control experiment (EXP_ORI), the model was initialized in its original form and in the second one (EXP_AJUST) the model was run to the same conditions as the EXP_ORI but with due adjustment made in BRAMS code. The model was run for a period of 774 hours, from 00 UTC of 1 January to 00 UTC of 1 February 2011. To facilitate the analysis of the impact of this adjustment on the mean daily cycle of thermodynamic variables of surface and convective precipitation, averages were performed in two different areas of 1° x 1°, an area of forested area (located in the south of the Amazon) and other deforested area on surface (located in northern Bolivia). Overall, the results showed that there were important differences in the thermodynamic profile of the lower troposphere due to the implementation of new setting in the BRAMS code. Values of moistening and heating rates in both areas peaked around 09 and 09:30 local time, although their net effect were felt later, the impact occurred mainly early afternoon. The daily cycle of surface fluxes were also sensitive to the adjustment performed in the model. Also the behavior and the amount of convective precipitation accumulated during the day in EXP_AJUST were improved, especially in deforested area.

Les objectifs de la présente thèse sont l'analyse des mécanismes de couplage surface-atmosphère contrôlant la température moyenne de surface et son cycle diurne dans les régions sèches, humides et de transition.Nous montrons le rôle clé de l'inertie thermique sur la température de surface dans les régions sèches. La sensibilité à l'inertie thermique de la température de nuit est plus élevée que la sensibilité de la température de jour, impactant la température moyenne journalière. Nous montrons que cet effet est directement lié à l'instabilité de la couche limite, plus forte le jour que la nuit. Nous mettons également en lumière le double rôle du forçage solaire : Le premier est d'être la source du contraste diurne de la couche limite, à l'origine de la dissymétrie de réponse de la température à l'inertie thermique, le second est d'atténuer cet effet, puisque la forte dissymétrie du forçage solaire favorise la sensibilité de la température de jour par rapport à la nuit.Dans les régions humides, nous constatons que la sensibilité de la température de surface à l'inertie thermique est très faible. Ceci est dû aux fortes valeurs du flux latent qui contrôle la température de surface. Néanmoins, nous signalons que l'inertie thermique peut impacter le bilan d'eau à la surface, comme dans la région de la mousson indienne par exemple.Dans les régions de transition, nous montrons que la relation entre la température et l'humidité de surface est atténuée de 20 à 50 \% environ, du fait de la dépendance de l'inertie thermique à l'humidité de surface. Nous suggérons ainsi d'intégrer l'effet de l'humidité sur l'inertie thermique en plus de son effet sur l'évaporation. / The main objectives of this study are to analyze the surface-atmosphere coupling mechanisms controlling the mean temperature and its diurnal cycle in the dry, humid and transitional zones. We show that thermal inertia plays a key role on the surface temperature in dry regions. The sensitivity of surface temperature to thermal inertia is high during the night but low during the day, impacting the mean surface temperature. We demonstrate that this effect is directly related to the instability of the planetary boundary layer, which is higher during the day compared to the night.Moreover, we emphasize the dual role of the solar forcing. The first one is to be the source of the diurnal contrast of the planetary boundary layer, which is the origin of the diurnal asymmetry of the surface temperature response to thermal inertia. The second one is to attenuate this effect, since the high asymmetry of the solar forcing foster the sensitivity of the day temperature compared to the night. In humid regions, we notice that the sensitivity of the surface temperature to thermal inertia is weak. This is due to the high values of the latent heat flux which controls the surface temperature. Nevertheless, we should point out that the thermal inertia may have an impact on the water budget at the surface, as it is the case in the Indian Monsoon region. In the transitional regions, we show that the relation between surface temperature and soil moisture is attenuated by about 20 to 50 % because of the dependency of the thermal inertia to soil water content. Hence, we suggest to integrated the effect of soil moisture on the thermal inertia in addition to its effect on evaporation.

The Charles University Large-eddy Microscale Model (CLMM) and its application are presented. It is a numerical model for simulation of turbulent flow and dispersion in the planetary boundary layer. CLMM solves the incompressible Navier-Stokes equations in the Boussinesq approximation and describes turbulence using the large eddy simulation. Three applications of the model are presented. In the first case, the model is applied to the stable boundary layer over a flat terrain. The second case presents the simulations of stably stratified flows over obstacles. The last case deals with the dispersion of a hazardous material within an urban canopy. It was performed in the frame of the COST Action ES1006 and uses the Michelstadt flow and dispersion dataset for model validation.

The use of numerical weather prediction (NWP) has brought significant improvements to severe weather outbreak forecasting; however, determination of the primary mode of severe weather (in particular tornadic and nontornadic outbreaks) continues to be a challenge. Uncertainty in model runs contributes to forecasting difficulty; therefore it is beneficial to a forecaster to understand the sources and magnitude of uncertainty in a severe weather forecast. This research examines the impact of data assimilation, microphysics parameterizations, and planetary boundary layer (PBL) physics parameterizations on severe weather forecast accuracy and model variability, both at a mesoscale and synoptic-scale level. NWP model simulations of twenty United States tornadic and twenty nontornadic outbreaks are generated. In the first research phase, each case is modeled with three different modes of data assimilation and a control. In the second phase, each event is modeled with 15 combinations of physics parameterizations: five microphysics and three PBL, all of which were designed to perform well in convective weather situations. A learning machine technique known as a support vector machine (SVM) is used to predict outbreak mode for each run for both the data assimilated model simulations and the different parameterization simulations. Parameters determined to be significant for outbreak discrimination are extracted from the model simulations and input to the SVM, which issues a diagnosis of outbreak type (tornadic or nontornadic) for each model run. In the third phase, standard synoptic parameters are extracted from the model simulations and a k-means cluster analysis is performed on tornadic and nontornadic outbreak data sets to generate synoptically distinct clusters representing atmospheric conditions found in each type of outbreak. Variations among the synoptic features in each cluster are examined across the varied physics parameterization and data assimilation runs. Phase I found that conventional and HIRS-4 radiance assimilation performs best of all examined assimilation variations by lowering false alarm ratios relative to other runs. Phase II found that the selection of PBL physics produces greater spread in the SVM classification ability. Phase III found that data assimilation generates greater model changes in the strength of synoptic-scale features than either microphysics or PBL physics parameterization.

L'influence des paramétrisations chimiques et météorologiques sur les concentrations de polluants calculées avec un modèle de qualité de l'air est étudiée. L'influence des différences entre deux mécanismes chimiques de la phase gazeuse sur la formation d'ozone et d'aérosols en Europe est faible en moyenne. Pour l'ozone, les fortes différences observées localement proviennent principalement de l'incertitude associée à la cinétique des réactions d'oxydation du monoxyde d'azote (NO) d'une part et de la représentation des différents chemins d'oxydation des composés aromatiques d'autre part. Les concentrations d'aérosols sont surtout influencées par la prise en compte des précurseurs majeurs d'aérosols secondaires et le traitement explicite des régimes chimiques correspondant au niveau d'oxydes d'azote (NOx). L'influence des paramétrisations météorologiques sur les concentrations d'aérosols et leur répartition verticale est évaluée sur l'Île de France par comparaison à des données lidar. L'influence de la paramétrisation de la dynamique de la couche limite atmosphérique est importante ; cependant, c'est l'utilisation d'un modèle de canopée urbaine qui permet d'améliorer considérablement la modélisation de la répartition verticale des polluants / The influence of chemical mechanisms and meteorological parameterizations on pollutant concentrations calculated with an air quality model is studied. The influence of the differences between two gas-phase chemical mechanisms on the formation of ozone and aerosols in Europe is low on average. For ozone, the large local differences are mainly due to the uncertainty associated with the kinetics of nitrogen monoxide (NO) oxidation reactions on the one hand and the representation of different pathways for the oxidation of aromatic compounds on the other hand. The aerosol concentrations are mainly influenced by the selection of all major precursors of secondary aerosols and the explicit treatment of chemical regimes corresponding to the nitrogen oxides (NOx) levels. The influence of the meteorological parameterizations on the concentrations of aerosols and their vertical distribution is evaluated over the Paris region in France by comparison to lidar data. The influence of the parameterization of the dynamics in the atmospheric boundary layer is important ; however, it is the use of an urban canopy model that improves significantly the modeling of the pollutant vertical distribution

The influence of chemical mechanisms and meteorological parameterizations on pollutant concentrations calculated with an air quality model is studied. The influence of the differences between two gas-phase chemical mechanisms on the formation of ozone and aerosols in Europe is low on average. For ozone, the large local differences are mainly due to the uncertainty associated with the kinetics of nitrogen monoxide (NO) oxidation reactions on the one hand and the representation of different pathways for the oxidation of aromatic compounds on the other hand. The aerosol concentrations are mainly influenced by the selection of all major precursors of secondary aerosols and the explicit treatment of chemical regimes corresponding to the nitrogen oxides (NOx) levels. The influence of the meteorological parameterizations on the concentrations of aerosols and their vertical distribution is evaluated over the Paris region in France by comparison to lidar data. The influence of the parameterization of the dynamics in the atmospheric boundary layer is important ; however, it is the use of an urban canopy model that improves significantly the modeling of the pollutant vertical distribution