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Advances in Meteorology
Volume 2016, Article ID 8570581, 13 pages
Research Article

The Evolution of Temporal and Spatial Patterns of Carbon Monoxide Concentrations in the Metropolitan Area of Sao Paulo, Brazil

1School of Arts, Sciences and Humanities of the University of Sao Paulo (EACH-USP), Av. Arlindo Béttio 1000, Ermelino Matarazzo, 03828-000 Sao Paulo, SP, Brazil
2Institute of Astronomy, Geophysics and Atmospheric Sciences of the University of Sao Paulo (IAG-USP), Rua do Matão 1226, Cidade Universitária, 05508-090 Sao Paulo, SP, Brazil

Received 15 April 2016; Revised 17 July 2016; Accepted 10 August 2016

Academic Editor: Ilan Levy

Copyright © 2016 Flavia Noronha Dutra Ribeiro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The Environmental Agency of Sao Paulo has a large dataset of carbon monoxide measurements: 20 years of records in 18 automatic stations inside the metropolitan area. However, a thorough investigation on the time evolution of CO concentration tendency and cycles also considering spatial variability is lacking. The investigation consists of a trend line analysis, a periodogram analysis, a correlation between CO concentration and meteorological variables, and spatial distribution of CO concentration. Local and federal policies helped in decreasing CO concentrations and the highest decreasing rate was 0.7% per month. This tendency is lately stabilizing, since the vehicles fleet is increasing. CO most relevant cycles are annual and diurnal and a few series indicate a weekly cycle. Diurnal cycle shows two peaks, morning and evening rush hours, 1.2 and 1.1 ppm, respectively, in 2012. However, lately there is an extended evening peak (20 h to 23 h), related to changes in emission patterns. The spatial analysis showed that CO concentration has high spatial variability and is influenced by proximity to heavy traffic and vegetated areas. The present work indicates that several processes affect CO concentration and these results form a valuable basis for other studies involving air quality modeling, mitigation, and urban planning.