Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China

In this study, we investigated six air pollutants from 21 monitoring stations scattered throughout Wuhan city by analyzing meteorological variables in the atmospheric boundary layer (ABL) and air mass backward trajectories from HYSPLIT during the pollution events. Together with this, ground meteorol...

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Main Authors:	Yassin Mbululo, Jun Qin, Jun Hong, Zhengxuan Yuan
Format:	Article
Language:	English
Published:	MDPI AG 2018-09-01
Series:	Atmosphere
Subjects:	atmospheric boundary layer air quality index PM2.5 pollution ozone pollution trans-boundary movement
Online Access:	http://www.mdpi.com/2073-4433/9/9/359

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spelling	doaj-art-2b4b0fc2da4d4310a7e07153d9d48bfb2018-09-19T07:17:22ZengMDPI AGAtmosphere2073-44332018-09-019935910.3390/atmos9090359atmos9090359Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, ChinaYassin Mbululo0Jun Qin1Jun Hong2Zhengxuan Yuan3Institute of Atmospheric Physics and Atmospheric Environment, School of Environmental Studies, China University of Geosciences, Wuhan 430074, ChinaInstitute of Atmospheric Physics and Atmospheric Environment, School of Environmental Studies, China University of Geosciences, Wuhan 430074, ChinaInstitute of Atmospheric Physics and Atmospheric Environment, School of Environmental Studies, China University of Geosciences, Wuhan 430074, ChinaInstitute of Atmospheric Physics and Atmospheric Environment, School of Environmental Studies, China University of Geosciences, Wuhan 430074, ChinaIn this study, we investigated six air pollutants from 21 monitoring stations scattered throughout Wuhan city by analyzing meteorological variables in the atmospheric boundary layer (ABL) and air mass backward trajectories from HYSPLIT during the pollution events. Together with this, ground meteorological variables were also used throughout the investigation period: 1 December 2015 to 30 November 2016. Analysis results during this period show that the city was polluted in winter by PM2.5 (particulate matter with aerodynamics of less than 2.5 microns) and in summer by ozone (O3). The most polluted day during the investigation period was 25 December 2015 with an air quality index (AQI) of 330 which indicates ‘severe pollution’, while the cleanest day was 26 August 2016 with an AQI of 27 indicating ‘excellent’ air quality. The average concentration of PM2.5 (O3) on the most polluted day was 265.04 (135.82) µg/m3 and 9.10 (86.40) µg/m3 on the cleanest day. Moreover, the percentage of days which exceeded the daily average limit of NO2, PM10, PM2.5, and O3 for the whole year was 2.46%, 14.48%, 23.50%, and 39.07%, respectively, while SO2 and CO were found to be below the set daily limit. The analysis of ABL during PM2.5 pollution events showed the existence of a strong inversion layer, low relative humidity, and calm wind. These observed conditions are not favorable for horizontal and vertical dispersion of air pollutants and therefore result in pollutant accumulation. Likewise, ozone pollution events were accompanied by extended sunshine hours, high temperature, a calm wind, a strongly suspended inversion layer, and zero recorded rainfall. These general characteristics are favorable for photochemical production of ozone and accumulation of pollutants. Apart from the conditions of ABL, the results from backward trajectories suggest trans-boundary movement of air masses to be one of the important factors which determines the air quality of Wuhan.http://www.mdpi.com/2073-4433/9/9/359atmospheric boundary layerair quality indexPM2.5 pollutionozone pollutiontrans-boundary movement
institution	Open Data Bank
collection	Open Access Journals
building	Directory of Open Access Journals
language	English
format	Article
author	Yassin Mbululo Jun Qin Jun Hong Zhengxuan Yuan
spellingShingle	Yassin Mbululo Jun Qin Jun Hong Zhengxuan Yuan Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China Atmosphere atmospheric boundary layer air quality index PM2.5 pollution ozone pollution trans-boundary movement
author_facet	Yassin Mbululo Jun Qin Jun Hong Zhengxuan Yuan
author_sort	Yassin Mbululo
title	Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China
title_short	Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China
title_full	Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China
title_fullStr	Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China
title_full_unstemmed	Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China
title_sort	characteristics of atmospheric boundary layer structure during pm2.5 and ozone pollution events in wuhan, china
publisher	MDPI AG
series	Atmosphere
issn	2073-4433
publishDate	2018-09-01
description	In this study, we investigated six air pollutants from 21 monitoring stations scattered throughout Wuhan city by analyzing meteorological variables in the atmospheric boundary layer (ABL) and air mass backward trajectories from HYSPLIT during the pollution events. Together with this, ground meteorological variables were also used throughout the investigation period: 1 December 2015 to 30 November 2016. Analysis results during this period show that the city was polluted in winter by PM2.5 (particulate matter with aerodynamics of less than 2.5 microns) and in summer by ozone (O3). The most polluted day during the investigation period was 25 December 2015 with an air quality index (AQI) of 330 which indicates ‘severe pollution’, while the cleanest day was 26 August 2016 with an AQI of 27 indicating ‘excellent’ air quality. The average concentration of PM2.5 (O3) on the most polluted day was 265.04 (135.82) µg/m3 and 9.10 (86.40) µg/m3 on the cleanest day. Moreover, the percentage of days which exceeded the daily average limit of NO2, PM10, PM2.5, and O3 for the whole year was 2.46%, 14.48%, 23.50%, and 39.07%, respectively, while SO2 and CO were found to be below the set daily limit. The analysis of ABL during PM2.5 pollution events showed the existence of a strong inversion layer, low relative humidity, and calm wind. These observed conditions are not favorable for horizontal and vertical dispersion of air pollutants and therefore result in pollutant accumulation. Likewise, ozone pollution events were accompanied by extended sunshine hours, high temperature, a calm wind, a strongly suspended inversion layer, and zero recorded rainfall. These general characteristics are favorable for photochemical production of ozone and accumulation of pollutants. Apart from the conditions of ABL, the results from backward trajectories suggest trans-boundary movement of air masses to be one of the important factors which determines the air quality of Wuhan.
topic	atmospheric boundary layer air quality index PM2.5 pollution ozone pollution trans-boundary movement
url	http://www.mdpi.com/2073-4433/9/9/359
_version_	1612548333484638208

Characteristics of Atmospheric Boundary Layer Structure during PM2.5 and Ozone Pollution Events in Wuhan, China

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