Impact of vehicular emissions on the formation of fine particles in the Sao Paulo Metropolitan Area: a numerical study with the WRF-Chem model

Autor(es)

Vara-Vela, A. ^[1] ; Andrade, M. F. ^[1] ; Kumar, P. ^{[2, 3]} ; Ynoue, R. Y. ^[1] ; Munoz, A. G. ^{[4, 5]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geophys & Atmospher Sci, Dept Atmospher Sci, Sao Paulo - Brazil

^[2] Univ Surrey, FEPS, Dept Civil & Environm Engn, Guildford GU2 7XH, Surrey - England

^[3] Univ Surrey, Fac Engn & Phys Sci, Environmental Flow EnFlo Res Ctr, Guildford GU2 7XH, Surrey - England

^[4] Columbia Univ, Int Res Inst Climate & Soc IRI, Palisades, NY 10964 - USA

^[5] Univ Zulia, CMC, Maracaibo 4011 - Venezuela

• Tipo de documento: Artigo Científico
• Fonte: Atmospheric Chemistry and Physics; v. 16, n. 2, p. 777-797, 2016.
• Citações Web of Science: 16

Resumo

The objective of this work is to evaluate the impact of vehicular emissions on the formation of fine particles (PM2.5; <= 2.5 mu m in diameter) in the Sao Paulo Metropolitan Area (SPMA) in Brazil, where ethanol is used intensively as a fuel in road vehicles. The Weather Research and Forecasting with Chemistry (WRF-Chem) model, which simulates feedbacks between meteorological variables and chemical species, is used as a photochemical modelling tool to describe the physico-chemical processes leading to the evolution of number and mass size distribution of particles through gas-to-particle conversion. A vehicular emission model based on statistical information of vehicular activity is applied to simulate vehicular emissions over the studied area. The simulation has been performed for a 1-month period (7 August-6 September 2012) to cover the availability of experimental data from the NUANCE-SPS (Narrowing the Uncertainties on Aerosol and Climate Changes in Sao Paulo State) project that aims to characterize emissions of atmospheric aerosols in the SPMA. The availability of experimental measurements of atmospheric aerosols and the application of the WRF-Chem model made it possible to represent some of the most important properties of fine particles in the SPMA such as the mass size distribution and chemical composition, besides allowing us to evaluate its formation potential through the gas-to-particle conversion processes. Results show that the emission of primary gases, mostly from vehicles, led to a production of secondary particles between 20 and 30% in relation to the total mass concentration of PM2.5 in the downtown SPMA. Each of PM2.5 and primary natural aerosol (dust and sea salt) contributed with 40-50% of the total PM10 (i.e. those <= 10 mu m in diameter) concentration. Over 40% of the formation of fine particles, by mass, was due to the emission of hydrocarbons, mainly aromatics. Furthermore, an increase in the number of small particles impaired the ultraviolet radiation and induced a decrease in ozone formation. The ground-level O-3 concentration decreased by about 2% when the aerosol-radiation feedback is taken into account. (AU)

• Processo FAPESP: 08/58104-8 - Narrowing the uncertainties on aerosol and climate changes in São Paulo State: NUANCES-SPS
• Beneficiário: Maria de Fátima Andrade
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático