Fog, Temperature and Air Quality Over the Metropolitan Area of São Paulo: a Trend Analysis from 1998 to 2018

AbstractThis study investigates the long-term development of fog occurrences in the Metropolitan Area of São Paulo (MASP). Specifically, it analyzes the roles of meteorological and air quality parameters as potential drivers for fog formation. A dataset reaching back to the year 1933 shows that the overall trends of the annual fog occurrences (AFO) coincide with those of the annual mean temperature. Air quality data have been available since 1998, allowing us to perform a statistical analysis of the contributions of meteorology and air quality to AFO for the period from 1998 to 2018. The logistic regression model shows that the binary dependent variable (daily fog occurrence, FO) is explained by its independent predictors PM10, relative humidity (rH), and daily minimum temperature (Tmin), in that order. FO was not found to be significantly influenced by atmospheric pressure (aP) and nitrogen oxides (NOx). While the influence of SO2 was minor and associated with less confidence, it was negative. Potential causes for these surprising results are discussed. We conclude that the parameters PM10, rH, and Tmin are significant drivers of fog formation in the MASP, whereby the total explanatory power of the drivers for the dichotomous variable FO is 16%.

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Characterization of Air-Quality Degradation Episodes of PM10 in the Metropolitan Area of São Paulo and Their Relationship with Meteorological Conditions

Environmental Sciences Proceedings ◽

10.3390/ecas2020-08143 ◽

2020 ◽

Vol 4 (1) ◽

pp. 8

Author(s):

Maria C. Q. D. Oliveira ◽

Luciana V. Rizzo ◽

Anita Drumond

Keyword(s):

Air Quality ◽

Metropolitan Area ◽

Sao Paulo ◽

Meteorological Conditions ◽

Pollutant Emissions ◽

Maximum Temperature ◽

São Paulo ◽

Urban Centers ◽

Duration Distribution ◽

Air Quality Monitoring Stations

Air pollution is one of the main environmental problems in large urban centers, affecting people’s health and impacting quality of life. The Metropolitan Area of São Paulo (MASP) presents frequent exceedances of air-quality standards in inhalable particulate matter (PM10), a consequence of pollutant emissions modulated by meteorological conditions. This study aims to identify and characterize PM10persistent exceedance events (PEE) inthe MASP between 2005 and 2017, relating them to meteorological conditions. The criteria used to select the events were: (i) events that occurred in at least 50% of the air-quality monitoring stations chosen for this study and, (ii) among the events that met the first criterion, those with a duration equal to or greater than five days, which correspond to the 80% percentile of the event duration distribution. A total 71 persistent episodes of exceedance were selected. The results show that the exceedance of PM10 lasted up to 14 consecutive days and was predominant in the austral winter, accompanied by an increase in maximum temperature (T), a decrease in wind speed (WS) and relative humidity (RH), and a wind direction predominantly from the northwest during the peak concentration of the pollutant. On average, a concentration increase of 60% was observed at the peak of the PEE.

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Influence of a Biomass-Burning Event in PM2.5 Concentration and Air Quality: A Case Study in the Metropolitan Area of São Paulo

Sensors ◽

10.3390/s21020425 ◽

2021 ◽

Vol 21 (2) ◽

pp. 425

Author(s):

Gregori de Arruda Moreira ◽

Izabel da Silva Andrade ◽

Alexandre Cacheffo ◽

Fábio Juliano da Silva Lopes ◽

Alexandre Calzavara Yoshida ◽

...

Keyword(s):

Air Quality ◽

Biomass Burning ◽

Metropolitan Area ◽

Sao Paulo ◽

Aerosol Layer ◽

São Paulo ◽

Air Masses ◽

Novel Approach ◽

Quality Classification ◽

Entrainment Process

Severe biomass burning (BB) events have become increasingly common in South America in the last few years, mainly due to the high number of wildfires observed recently. Such incidents can negatively influence the air quality index associated with PM2.5 (particulate matter, which is harmful to human health). A study performed in the Metropolitan Area of São Paulo (MASP) took place on selected days of July 2019, evaluated the influence of a BB event on air quality. Use of combined remote sensing, a surface monitoring system and data modeling and enabled detection of the BB plume arrival (light detection and ranging (lidar) ratio of (50 ± 34) sr at 532 nm, and (72 ± 45) sr at 355 nm) and how it affected the Ångström exponent (>1.3), atmospheric optical depth (>0.7), PM2.5 concentrations (>25 µg.m−3), and air quality classification. The utilization of high-order statistical moments, obtained from elastic lidar, provided a new way to observe the entrainment process, allowing understanding of how a decoupled aerosol layer influences the local urban area. This new novel approach enables a lidar system to obtain the same results as a more complex set of instruments and verify how BB events contribute from air masses aloft towards near ground ones.

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