Abstract
Abstract. In the 2015 winter month of December, northern China witnessed the most severe air pollution phenomena since the 2013 winter haze events occurred. This triggered the first-ever red alert in the air pollution control history of Beijing, with an instantaneous fine particulate matter (PM2. 5) concentration over 1 mg m−3. Air quality observations reveal large temporal–spatial variations in PM2. 5 concentrations over the Beijing–Tianjin–Hebei (Jing-Jin-Ji) area between 2014 and 2015. Compared to 2014, the PM2. 5 concentrations over the area decreased significantly in all months except November and December of 2015, with an increase of 36 % in December. Analysis shows that the PM2. 5 concentrations are significantly correlated with the local meteorological parameters in the Jing-Jin-Ji area such as the stable conditions, relative humidity (RH), and wind field. A comparison of two month simulations (December 2014 and 2015) with the same emission data was performed to explore and quantify the meteorological impacts on the PM2. 5 over the Jing-Jin-Ji area. Observation and modeling results show that the worsening meteorological conditions are the main reasons behind this unusual increase of air pollutant concentrations and that the emission control measures taken during this period of time have contributed to mitigate the air pollution ( ∼ 9 %) in the region. This work provides a scientific insight into the emission control measures vs. the meteorology impacts for the period.
Highlights
Severe air pollution has been observed in China for the last 15–20 years, with an annual mean concentration of fine particulate matter (PM2.5) ranging from 80 to 120 μg m−3 and over 1000 μg m−3 during some heavy haze episodes
This paper presents an analysis and modeling study of air pollution conditions in December 2015 in the Beijing– Tianjin–Hebei (Jing-Jin-Ji) area located in north China, and it explores the major reasons behind these unusual increases from both the meteorological and emission points of view
It was discovered that the monthly mean PM2.5 concentrations in December 2015 saw a large increase compared to the same month in 2014, ranging from 5 to 137 % in the Jing-Jin-Ji area with a mean increase of 36 %
Summary
Severe air pollution has been observed in China for the last 15–20 years, with an annual mean concentration of fine particulate matter (PM2.5) ranging from 80 to 120 μg m−3 and over 1000 μg m−3 during some heavy haze episodes. The haze phenomenon has become a major pollution problem in many China cities (Han et al, 2013; Wang et al, 2015), which causes wide public concern and has an adverse impact on human health and the environment (Gurjar et al, 2010; Kan et al, 2012). Since the strict control measures of air pollutants over the country were enforced in 2013 by the government, a steady decrease of air pollutant concentrations has been observed with the annual mean PM2.5 concentration dropping from about 85 μg m−3 in 2014 to 80 μg m−3 in 2015 for Beijing, from 86 to 70 μg m−3 for Tianjin, and from 118 to 88 μg m−3 for Shijiazhuang (three typical cities in north China, http://www.mep.gov.cn/gkml/).
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