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Impact of the 2015 El Nino event on winter air quality in China

View Article: PubMed Central - PubMed

ABSTRACT

During the winter of 2015, there was a strong El Nino (ENSO) event, resulting in significant anomalies for meteorological conditions in China. Analysis shows that the meteorological conditions in December 2015 (compared to December 2014) had several important anomalies, including the following: (1) the surface southeasterly winds were significantly enhanced in the North China Plain (NCP); (2) the precipitation was increased in the south of eastern China; and (3) the wind speeds were decreased in the middle-north of eastern China, while slightly increased in the south of eastern China. These meteorological anomalies produced important impacts on the aerosol pollution in eastern China. In the NCP region, the PM2.5 concentrations were significantly increased, with a maximum increase of 80–100 μg m−3. A global chemical/transport model (MOZART-4) was applied to study the individual contribution of the changes in winds and precipitation to PM2.5 concentrations. This study suggests that the 2015El Nino event had significant effects on air pollution in eastern China, especially in the NCP region, including the capital city of Beijing, in which aerosol pollution was significantly enhanced in the already heavily polluted capital city of China.

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(a) Monthly mean anomalies of vertically integrated (1000 hPa to 700 hPa) moisture flux (g m−1 s−1) between Dec. 2015 and Dec. 2014, and (b) anomalies of occurrence frequency (%) of moderate-heavy precipitation (precipitation > 10 mm day−1) in eastern Asia. NCEP /NCAR re-analysis data were applied in the study. The Data/image provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd. The map was generated by The NCAR Command Language (Version 6.3.0) [Software]. (2016). Boulder, Colorado: UCAR/NCAR/CISL/TDD. http://dx.doi.org/10.5065/D6WD3XH5.
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f2: (a) Monthly mean anomalies of vertically integrated (1000 hPa to 700 hPa) moisture flux (g m−1 s−1) between Dec. 2015 and Dec. 2014, and (b) anomalies of occurrence frequency (%) of moderate-heavy precipitation (precipitation > 10 mm day−1) in eastern Asia. NCEP /NCAR re-analysis data were applied in the study. The Data/image provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd. The map was generated by The NCAR Command Language (Version 6.3.0) [Software]. (2016). Boulder, Colorado: UCAR/NCAR/CISL/TDD. http://dx.doi.org/10.5065/D6WD3XH5.

Mentions: Figure 2a shows the anomalies of the water vapor flux between Dec. 2015 and Dec. 2014, which were calculated by the vertical integration (1000 hPa to 700 hPa) of moisture flux (g m−1 s−1), and Fig. 2b shows the anomalies of the frequency of moderate-heavy precipitation (defined as precipitation > 10 mm day−1) in China. Two water vapor paths were highlighted during the 2015-ENSO. One originated in the Bay of Bengal and was transported to the continent of South China. Another originated in the South China Sea and was transported to the continent of South China. These two paths converged over the continent of South China, producing higher precipitation in this region (in the south of the Yangtze River) in Dec. 2015 than in Dec. 2014. As shown in Fig. 2b, the frequency of moderate-heavy precipitation significantly increased, with a maximum increase of 15–20% during the 2015-ENSO event. The increased precipitation tended to decrease the PM2.5 concentrations due to the particle washout process910.


Impact of the 2015 El Nino event on winter air quality in China
(a) Monthly mean anomalies of vertically integrated (1000 hPa to 700 hPa) moisture flux (g m−1 s−1) between Dec. 2015 and Dec. 2014, and (b) anomalies of occurrence frequency (%) of moderate-heavy precipitation (precipitation > 10 mm day−1) in eastern Asia. NCEP /NCAR re-analysis data were applied in the study. The Data/image provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd. The map was generated by The NCAR Command Language (Version 6.3.0) [Software]. (2016). Boulder, Colorado: UCAR/NCAR/CISL/TDD. http://dx.doi.org/10.5065/D6WD3XH5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037463&req=5

f2: (a) Monthly mean anomalies of vertically integrated (1000 hPa to 700 hPa) moisture flux (g m−1 s−1) between Dec. 2015 and Dec. 2014, and (b) anomalies of occurrence frequency (%) of moderate-heavy precipitation (precipitation > 10 mm day−1) in eastern Asia. NCEP /NCAR re-analysis data were applied in the study. The Data/image provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd. The map was generated by The NCAR Command Language (Version 6.3.0) [Software]. (2016). Boulder, Colorado: UCAR/NCAR/CISL/TDD. http://dx.doi.org/10.5065/D6WD3XH5.
Mentions: Figure 2a shows the anomalies of the water vapor flux between Dec. 2015 and Dec. 2014, which were calculated by the vertical integration (1000 hPa to 700 hPa) of moisture flux (g m−1 s−1), and Fig. 2b shows the anomalies of the frequency of moderate-heavy precipitation (defined as precipitation > 10 mm day−1) in China. Two water vapor paths were highlighted during the 2015-ENSO. One originated in the Bay of Bengal and was transported to the continent of South China. Another originated in the South China Sea and was transported to the continent of South China. These two paths converged over the continent of South China, producing higher precipitation in this region (in the south of the Yangtze River) in Dec. 2015 than in Dec. 2014. As shown in Fig. 2b, the frequency of moderate-heavy precipitation significantly increased, with a maximum increase of 15–20% during the 2015-ENSO event. The increased precipitation tended to decrease the PM2.5 concentrations due to the particle washout process910.

View Article: PubMed Central - PubMed

ABSTRACT

During the winter of 2015, there was a strong El Nino (ENSO) event, resulting in significant anomalies for meteorological conditions in China. Analysis shows that the meteorological conditions in December 2015 (compared to December 2014) had several important anomalies, including the following: (1) the surface southeasterly winds were significantly enhanced in the North China Plain (NCP); (2) the precipitation was increased in the south of eastern China; and (3) the wind speeds were decreased in the middle-north of eastern China, while slightly increased in the south of eastern China. These meteorological anomalies produced important impacts on the aerosol pollution in eastern China. In the NCP region, the PM2.5 concentrations were significantly increased, with a maximum increase of 80–100 μg m−3. A global chemical/transport model (MOZART-4) was applied to study the individual contribution of the changes in winds and precipitation to PM2.5 concentrations. This study suggests that the 2015El Nino event had significant effects on air pollution in eastern China, especially in the NCP region, including the capital city of Beijing, in which aerosol pollution was significantly enhanced in the already heavily polluted capital city of China.

No MeSH data available.


Related in: MedlinePlus