Evaluación de la calidad del aire en Lima Metropolitana 2011

"Un medioambiente equilibrado y adecuado para el desarrollo de la vida constituye un derecho fundamental de las personas y la sociedad, reconocido por la Constitución Política del Perú y las normas ambientales vigentes. En este marco, el Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI) cumple un rol primordial en la vigilancia y pronóstico de la contaminación atmosférica en Lima Metropolitana, con la finalidad de preservar el medioambiente de los peligros de la contaminación tal como indica el artículo 4 inciso n) de la Ley 24031".-- Presentació

De global ao local: Um estudo multi-escalas de modelagem de qualidade do ar na Região Metropolitana de São Paulo

Air pollution is a multi-scale environmental problem that starts at the local scale, but its effects surpass the limits of cities in different scales of space and time. Measurements from air quality and meteorological stations are the main source of information on the state of the atmosphere. However, they are restricted in spatial coverage, limited in data interpretation, and are expensive to implement. Air quality models, by solving atmospheric motion equations and chemical reactions, offer an alternative approach to study air pollution by providing high temporal and spatial information of air pollutant concentration and meteorology. We used air quality models and emission inventories at different scales to study air quality in the Metropolitan Area of São Paulo (MASP). Output from the Community Atmosphere Model with Chemistry (CAM-Chem) global model is downloaded to be applied as dynamic chemical boundary conditions (CBC) for the Weather Research and Forecasting with Chemistry (WRF-Chem) community model. Then, WRF-Chem is used to simulate air quality at a regional and urban scale, considering Southeast Brazil and the MASP as simulation domains. Finally, the Model of Urban Network of Intersecting Canyons and Highways (MUNICH) is used to perform the first air quality simulation inside São Paulo urban canyons. During this process, we developed a new methodology to spatially disaggregate vehicular emissions based on total emissions and road length; and created a new tool to build WRF-Chem anthropogenic emission files. We also coded an R package to download and get high-quality data ready for analysis from the São Paulo State Environmental Agency air quality network that allows the automatization of model evaluation using all the available information. Results showed that CAM-Chem is suitable as CBC for WRF-Chem and can simulate coherently O3 and PM2.5 over the whole MASP with correlation coefficients greater than 0.7, but highly underestimates and fails to simulate primary pollutants. Both regional and urban WRF-Chem simulations achieved the meteorological benchmark of performance (e.g. ± 0.5 K mean bias of temperature, ± 10% mean bias of relative humidity, and ± 1.5 ms1 mean bias of wind speed). WRF-Chem presents an underestimation of primary pollutant with normalized mean bias (NMB) lower than -35 %, while O3 is best simulated achieving goal benchmarks with correlation coefficient of 0.83 and NMB of -5 %. MUNICH air quality simulation using WRF-Chem urban domain results as input improves NOX simulations with a NMB of -20 %. These simulations are an example of the capabilities that models have to address different scientific questions and how they can work to establish a multi-scale modeling system for air quality forecast. These tools allow the evaluation of air quality at different scales, the assessment of the efficacy of air pollution control policies, and the study of pollution health impact of pollutant exposure, even at street level.A poluição do ar é um problema ambiental que começa numa escala local, mas os seus efeitos vão além dos limites das cidades em diferentes escalas do espaço e tempo. As medições nas estações de qualidade do ar são a principal fonte de informação sobre o estado da atmosfera. Porém, elas possuem limitações na cobertura espacial, na interpretação da informação, e a sua implementação pode ser cara. Os modelos de qualidade do ar, através da solução das equações do movimento e das reações químicas da atmosfera, representam uma alternativa para investigar a qualidade do ar, fornecendo informação das concentrações de poluentes e as condições meteorológicas com diversa resolução espacial e temporal. Neste trabalho, diferentes modelos de qualidade do ar e inventários de emissões, em diferentes resoluções espaciais, são utilizados para estudar a qualidade do ar na região metropolitana de São Paulo (RMSP). Produtos do modelo global Community Atmosphere Model with Chemistry (CAM-Chem) são usados como condições de contorno químicas (CQC) para o modelo Weather Research and Forecasting with Chemistry (WRF-Chem). Em seguida, WRF-Chem é usado para simular a qualidade do ar na escala regional e urbana, através de domínios que cobrem a região sudeste do Brasil e a RMSP. Finalmente, o Model of Urban Network of Intersecting Canyons and Highways (MUNICH) é usado para simular ozônio e NOX dentro dos cânions urbanos, considerando como exemplo o distrito de Pinheiros. Desenvolvemos uma nova metodologia para distribuir espacial e temporalmente as emissões veiculares baseada nas emissões totais e o comprimento das estradas; e criamos um programa para construir o arquivo de emissões antropogênicas do WRF-Chem. Também desenvolvemos um pacote no R para fazer download e gerar dados prontos para serem analisados da Rede de Estações de Qualidade do Ar da CETESB, permitindo a automatização da avaliação dos modelos de qualidade do ar utilizando toda a informação disponível. Os resultados mostraram que o CAM-Chem, além de servir como CQC, representou adequadamente as concentrações de ozônio e PM2.5 para toda a RMSP com coeficientes de correlação maiores que 0.7, enquanto os poluentes primários são altamente subestimados. O WRF-Chem atingiu as benchmarks meteorológicos para ambos os domínios (e.g. ± 0.5 K de sesgo médio para temperatura, ± 10 % para umidade relativa, e ± 1.5 ms 1 para velocidade do vento). WRF-Chem subestimou as concentrações dos poluentes primários com sesgos médio normalizado (NMB) menores que -35 %, enquanto que o O3 atinge os benchmarks da acurácia com coeficiente de correlação de 0.83 e um NMB de -5 %. A simulação do MUNICH utilizando as simulações do domínio urbano do WRF-Chem melhoram a representação de NOX dentro dos cânions urbanos com um NMB de -20 %. Os resultados exemplificam as capacidades dos modelos para resolver diferentes questões sobre a formação e transporte dos poluentes atmosféricos em diferentes escalas. Esse sistema multi-escala permite a avaliação da qualidade do ar e da eficácia das políticas de controle da poluição do ar, e a realização de estudos de impacto à saúde dos poluentes atmosféricos

Impact of chemistry boundary conditions on tropospheric ozone simulations in the Metropolitan Area of São Paulo using WRF-Chem Model

O modelo WRF-Chem (Weather Research and Forecasting with Chemistry) vem sendo utilizado para simular a formação e o transporte de ozônio e material particulado na Região Metropolitana de São Paulo (RMSP). Estas simulações são uma ferramenta para entender a formação e o transporte destes poluentes desde áreas urbanas para os arredores e também a contribuição de fontes remotas para São Paulo. O objetivo desta pesquisa foi avaliar os impactos das condições de contorno químicas (CCQ) dependentes do tempo na representação do ozônio troposférico superficial e na sua estrutura vertical sobre a RMSP. O estudo avaliou o impacto das condições padrão do modelo WRF-Chem e as CCQ oriundas das saídas do MOZART -4 (Model for Ozone and Related Chemical Tracer Version 4), as quais são inseridas no modelo WRF-Chem usando a ferramenta mozbc. O período de estudo foi compreendido entre 15 e 18 de maio de 2006, 30 de outubro e 1 de novembro de 2006 e 29 de outubro a 04 de novembro de 2013, quando foram feitas sondagens de ozônio na cidade de São Paulo. Foram feitas duas simulações usando o mecanismo químico CBMZ para cada período variando as CCQ, de forma que qualquer alteração na representação do ozônio fosse causada somente pela modificação destas. As simulações foram comparadas com os dados das sondagens e com informações das estações de monitoramento de qualidade do ar da Companhia de Tecnologia de Saneamento Ambiental do Estado de São Paulo (CETESB). Os resultados mostraram que as maiores diferenças acontecem nas bordas do domínio de simulação e diminuem na direção dos ventos predominantes, para a RMSP as bordas Leste e Sul são as que mais afetam a simulação. As simulações usando CCQ do MOZART-4 geraram valores menores de concentração de ozônio na superfície diminuindo o desvio médio e em alguns casos melhorando o coeficiente de correlação. Existe uma melhora significativa na representação dos perfis de ozônio acima dos 3 km, o que indica que na superfície as principais forçantes são as emissões locais e nos níveis superiores são as CCQ.The WRF-Chem (Weather and Research Forecast with Chemistry Model) has been used to simulate the formation and transport of ozone and particulate matter in the Metropolitan Area of São Paulo (MASP), Brazil. The simulations are being considered as a tool to understand the transport of the pollutants from the urban area to the surroundings and the contribution of remote sources to the air quality of the city. The objective of this research was to assess the impacts of using time dependent chemical boundary conditions (CBC) on the simulation of ground-level ozone concentration and ozone vertical structure over the MASP. The CBC came from MOZART-4 chemistry transport model and was assimilated to WRF-Chem using the mozbc tool. Two simulations were carried out with CBMZ chemistry mechanism, the first one was set-up to run with an idealized profile (default case), and the second one enabling the new CBC from MOZART-4, making any variation on tropospheric ozone representation be caused by the modification of CBC. The period of study was from 15 - 18 May, from 30 October to 1 November of 2006 and from 29 October to 4 November of 2013, when ozonesondes were launched and surface concentrations measurements of pollutants were performed. The simulations were compared with observations from air quality stations located in the city and with the ozonesondes profiles. The results showed that the main differences between simulations are located in the domain boundaries, with the difference decreased during downwind transport. In the MASP southern and western boundaries were the most important. Also, there was an improvement in the representation of ozone vertical profiles over 3 km, which means that in lower levels the local emissions presented more influence than CBC. Using MOZART-4 boundary conditions resulted in lower surface ozone concentrations than simulated values using the default CBC, it decreased the mean bias and in some cases increased the correlation values

Emission factors for a biofuel impacted fleet in south America's largest metropolitan area

The Metropolitan Area of São Paulo (MASP) is among the largest urban areas in the Southern Hemisphere. Vehicular emissions are of great concern in metropolitan areas and MASP is unique due to the use of biofuels on a large scale (sugar-cane ethanol and biodiesel). In this work, tunnel measurements were employed to assess vehicle emissions and to calculate emission factors (EFs) for heavy-duty and light-duty vehicles (HDVs and LDVs). The EFs were determined for particulate matter (PM) and its chemical compounds. The EFs obtained for 2018 were compared with previous tunnel experiments performed in the same area. An overall trend of reduction of fine and coarse PM, organic carbon (OC), and elemental carbon (EC) EFs for both LDVs and HDVs was observed if compared to those observed in past years, suggesting the effectiveness of vehicular emissions control policies implemented in Brazil. A predominance of Fe, Cu, Al, and Ba metals emission was observed for the LDV fleet in the fine fraction. Cu presented higher emissions than two decades ago, which was associated with the increased use of ethanol fuel in the region. For HDVs, Zn and Pb were mostly emitted in the fine mode and were linked with lubricating oil emissions from diesel vehicles. A predominance in the emission of three- and four-ring polycyclic aromatic hydrocarbons (PAHs) for HDVs and five-ring PAHs for LDVs agreed with what was observed in previous studies. The use of biofuels may explain the lower PAH emissions for LDVs (including carcinogenic BaP) compared to those observed in other countries. The tendency observed was that LDVs emit higher amounts of carcinogenic species. The use of these real EFs in air quality modeling resulted in more accurate simulations of PM concentrations, showing the importance of updating data with real-world measurements.publishe