The Influence of Relative Humidity and Pollution on the Meteorological Optical Range During Rainy and Dry Months in Mexico City

The Meteorological Optical Range (<i>MOR</i>) is a measurement of atmospheric visibility. Visibility impairment has been linked to increased aerosol levels in the air. This study conducted statistical analyses using meteorological, air pollutant concentration, and <i>MOR</i>...

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Bibliographic Details
Main Authors: Blanca Adilen Miranda-Claudes, Guillermo Montero-Martínez
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Atmosphere
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Online Access:https://www.mdpi.com/2073-4433/15/11/1382
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Summary:The Meteorological Optical Range (<i>MOR</i>) is a measurement of atmospheric visibility. Visibility impairment has been linked to increased aerosol levels in the air. This study conducted statistical analyses using meteorological, air pollutant concentration, and <i>MOR</i> data collected in Mexico City from August 2014 to December 2015 to determine the factors contributing to haze occurrence (periods when <i>MOR</i> < 10,000 m), defined using a light scatter sensor (PWS100). The outcomes revealed seasonal patterns in PM<sub>2.5</sub> and relative humidity (<i>RH</i>) for haze occurrence along the year. PM<sub>2.5</sub> levels during hazy periods in the dry season were higher compared to the wet season, aligning with periods of poor air quality (PM<sub>2.5</sub> > 45 μg/m<sup>3</sup>). Pollutant-to-CO ratios suggested that secondary aerosols’ production, led by SO<sub>2</sub> conversion to sulfate particles, mainly impacts haze occurrence during the dry season. Meanwhile, during the rainy season, the PWS100 registered haze events even with PM<sub>2.5</sub> values close to 15 μg/m<sup>3</sup> (considered good air quality). The broadened distribution of extinction efficiency during the wet period and its correlation with <i>RH</i> suggest that aerosol water vapor uptake significantly impacts visibility during this season. Therefore, attributing poor visibility strictly to poor air quality may not be appropriate for all times and locations.
ISSN:2073-4433