Weekend/weekday differences in concentrations of ozone, nox, and non-methane hydrocarbon in the metropolitan area of São Paulo

Júnior, Rosiberto Salustiano da Silva; Oliveira, Marcio G. L; Andrade, María de Fátima

doi:10.1590/s0102-77862009000100010

Cited by 24 publications

(20 citation statements)

References 10 publications

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“…6. In general, the weekend particle number concentrations were lower than during weekdays, because there is less traffic during weekends (Silva Júnior et al, 2009). Sunday had the lowest and Friday the highest median particle number concentrations, 1.78 × 10 4 and 2.53 × 10 4 cm −3 respectively (Fig.…”

Section: Weekly Patternsmentioning

confidence: 98%

On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

Backman

Rizzo²,

Hakala

et al. 2012

Atmos. Chem. Phys.

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Abstract. Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of São Paulo (MASP, population 20 million) accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL) depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clearsky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 × 10 4 -3.2 × 10 4 cm −3 frequently exceeding 4 × 10 4 cm −3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC) were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength) varied in the range 12-33 Mm −1 and 21-64 Mm −1 , respectively. The former one is equal to 1.8-5.0 µg m −3 of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (ω 0 ) varied in the range 0.59-0.76. Overall, this suggests a top of atmosphere (TOA) warming effect. However, considering the low surface reflectance of urban areas, for the given range of ω 0 , the TOA radiative forcing can be either positive or negative for the sources within the MASP. On the average, weekend ω 0 values were 0.074 higher than during weekdays. During 11 % of the days, new particle formation (NPF) events occurred. The analysed events growth rates ranged between 9 and 25 nm h −1 . Sulphuric acid proxy concentrations calculated for the site were less than 5 % of the concentration needed to explain the observed growth. Thus, other vapours are likely contributors to the observed growth.

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Section: Weekly Patternsmentioning

confidence: 98%

On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

Backman

Rizzo²,

Hakala

et al. 2012

Atmos. Chem. Phys.

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“…The data also reveal that ozone (O 3 ) increases on weekend especially on Sundays contrary to decreasing concentration of other pollutants like NO x and some hydrocarbons which act as its precursors. Such observations are also referred to as "Weekend effect" by Blanchard et al [1], Fujita et al [3], Gour et al [4], Murphy (2007) et al [5], Rosiberto et al [9], Stephens et al [15], Debaje et al [16] and Tan et al [17]. On weekend, the reduced PM and aerosols result in more inward solar radiation accompanied with the precursor NO x accumulated over the week aids the ozone production.…”

Section: Pollution Emissionmentioning

confidence: 99%

“…Reddy and Venkataraman [7] and Abera et al [8] note that the pollutants like CO and NO x emanate from automobile exhausts, whereas use of coal based fuels causes heavy emissions of SO 2 . Murphy (2008) et al [2] and Rosibeto et al [9] find that the levels of O 3 , NO x and particulate matter are an issue of concern in the urban environment. The variation in concentration of such pollutants strongly relates to the pattern of human activities in the city.…”

Section: Pollution Emissionmentioning

confidence: 99%

Variation in Parameters of Ambient Air Quality in National Capital Territory (NCT) of Delhi (India)

Gour¹,

Singh²,

Tyagi³

et al. 2015

ACS

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Air Pollution is an escalating problem worldwide fuelled by increasing anthropogenic activities, speedy development, rapid industrialization, transportation, superfluous use of fossil fuel consumption, increasing global power needs, etc. Also the diverse meteorological factors influence our environment to a great extent. Population explosion has led to remarkable increase in vehicular population. The use solely depends upon the lifestyle of the citizen. Any change in the lifestyle has a remarkable effect on the air we breathe. A comprehensive database for pollution levels from the year 2006 to 2010 was analyzed for a main traffic intersection and a non-traffic area in Delhi (India). The paper asserts that pollutant concentration levels on weekend are lower than those on weekdays (increase on Sundays with respect to weekdays is CO 2.98 times, PM2.5 1.18 times, NO 1.62 times, NO2 5.76 times, SO 2 1.27 times and O 3 1.15 times). The pollution levels have been found to attenuate on public holidays and weekends. Pollution can hence be related to the weekly cycle of human activities. Pollutions due to vehicular emissions on roads, rails, air or water all serve as major sources of pollution. Hence, viably possible solutions for pollution control can also be achieved by controlling the magnitude of traffic flow on roads.

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“…Possui uma área de 8.051km² com uma população superior a 19 milhões de habitantes, distribuída em uma área urbanizada e de maneira desordenada em 1.747km² dessa área. O sítio urbano situa-se, praticamente, na Bacia Sedimentar de São Paulo, cujo principal vale é o do Rio Tietê, orientado no sentido Leste-Oeste, com uma altitude média de 720 metros e uma extensa planície de inundação (CETESB, 2005;Castanho, 2005;Silva Junior et al, 2009). Durante o inverno, formações de alta pressão no Oceano Atlântico ao Leste, dirigem-se para o Norte, produzindo ventos fracos provenientes da costa, fortes inversões térmicas de subsidência e céu claro.…”

Section: áRea De Estudounclassified

“…A simulação para gerar os dados de entrada teve como característica utilizar o padrão adotado pelo modelo WRF/Chem, que leva em consideração uma concentração inicial com base na interpretação do tipo de uso do solo. Para a condição de fronteira foram utilizados os resultados das simulações globais realizadas pelo modelo Max Planck Institut (MATCH-MPI -Lawrence, 1996;Silva Junior et al, 2009), de modo a tentar diminuir os problemas de borda do domínio, pois teoricamente a concentração seria zero fora do domínio, e dependendo da direção do vento, a concentração dos poluentes nas bordas poderia interferir em áreas mais próximas ao centro do domínio.…”

Section: Condição Inicial E De Fronteira Para a Química No Modelounclassified

Validação de poluentes fotoquímicos e inclusão do inventário de emissões no modelo de qualidade do ar WRF/CHEM, para a região metropolitana de São Paulo

Silva

Andrade

2013

Rev. bras. meteorol.

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Este trabalho mostra os resultados das aproximações feitas para o inventário de emissões de poluentes da Região Metropolitana de São Paulo (RMSP) e transformações necessárias para serem implementadas no modelo fotoquímico WRF/CHEM ("Weather Research and Forecasting / CHEMistry"). Portanto, o objetivo é avaliar a eficiência do modelo WRF/CHEM em simular os poluentes fotoquímicos para a RMSP, utilizando as concentrações de monóxido de carbono (CO) e ozônio troposférico (O3). O WRF/Chem é um modelo de previsão de tempo, clima e qualidade do ar, que resolve em conjunto e de forma simultânea os modulos de meteorologia e química. A RMSP é considerada uma das dez maiores metropoles do mundo, e sofre igualmente a outros centros urbanos com o problema da poluição atmosférica. Pesquisas realizadas na RMSP mostram que os automóveis são as principais fontes de CO, hidrocarbonetos totais (HC) e Óxidos Nitrogenados (NOx). Para Óxidos de Enxofre (SOx), as indústrias e os automóveis são fontes importantes na emissão de SOx e emissão de partículas inaláveis (PM10). Outro fator muito importante é a ressuspensão de partículas do solo e formação de aerossóis secundários. Para estimar as emissões será usado o estudo do inventário feito pela Companhia Ambiental do Estado de São Paulo (CETESB) para o ano de 2006, onde estas informações serão trabalhadas para adequação ao formato de entrada do modelo WRF/Chem, pois esse levantamento anual de emissãos de poluentes é feito para toda a RMSP. Logo, algumas das propostas foram de gerar aproximações para tornar as emissões mais representativas, em termos de distribuição espacial e temporal. Os resultados mostraram que tais aproximações melhoram a previsão da concentração de ozônio (O3) e de CO em cerca de 25%, atingindo coeficientes de correlação de 0,79 para ozônio e 0,49 para monóxido de carbono, quando comparado os dados simulados e observados.

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Weekend/weekday differences in concentrations of ozone, nox, and non-methane hydrocarbon in the metropolitan area of São Paulo

Cited by 24 publications

References 10 publications

On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

On the diurnal cycle of urban aerosols, black carbon and the occurrence of new particle formation events in springtime São Paulo, Brazil

Variation in Parameters of Ambient Air Quality in National Capital Territory (NCT) of Delhi (India)

Validação de poluentes fotoquímicos e inclusão do inventário de emissões no modelo de qualidade do ar WRF/CHEM, para a região metropolitana de São Paulo

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