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Volume 17, issue 7 | Copyright
Atmos. Chem. Phys., 17, 4799-4816, 2017
https://doi.org/10.5194/acp-17-4799-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 12 Apr 2017

Research article | 12 Apr 2017

Impacts of East Asian summer and winter monsoons on interannual variations of mass concentrations and direct radiative forcing of black carbon over eastern China

Yu-Hao Mao1,2, Hong Liao1,3, and Hai-Shan Chen3,4,5 Yu-Hao Mao et al.
  • 1School of Environmental Science and Engineering, Nanjing University of Information Science and Technology (NUIST), Nanjing 210044, China
  • 2Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, NUIST, Nanjing 210044, China
  • 3International Joint Research Laboratory on Climate and Environment Change (ILCEC), NUIST, Nanjing 210044, China
  • 4Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC)/Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), NUIST, Nanjing 210044, China
  • 5School of Atmospheric Sciences, NUIST, Nanjing 210044, China

Abstract. We applied a global three-dimensional chemical transport model (GEOS-Chem) to examine the impacts of the East Asian monsoon on the interannual variations of mass concentrations and direct radiative forcing (DRF) of black carbon (BC) over eastern China (110–125°E, 20–45°N). With emissions fixed at the year 2010 levels, model simulations were driven by the Goddard Earth Observing System (GEOS-4) meteorological fields for 1986–2006 and the Modern Era Retrospective-analysis for Research and Applications (MERRA) meteorological fields for 1980–2010. During the period of 1986–2006, simulated June–July–August (JJA) and December–January–February (DJF) surface BC concentrations were higher in MERRA than in GEOS-4 by 0.30µgm−3 (44%) and 0.77µgm−3 (54%), respectively, because of the generally weaker precipitation in MERRA. We found that the strength of the East Asian summer monsoon (EASM; East Asian winter monsoon, EAWM) negatively correlated with simulated JJA (DJF) surface BC concentrations (r = −0. 7 (−0.7) in GEOS-4 and −0.4 (−0.7) in MERRA), mainly by the changes in atmospheric circulation. Relative to the 5 strongest EASM years, simulated JJA surface BC concentrations in the 5 weakest monsoon years were higher over northern China (110–125°E, 28–45°N) by 0.04–0.09µgm−3 (3–11%), but lower over southern China (110–125°E, 20–27°N) by 0.03–0.04µgm−3 (10–11%). Compared to the 5 strongest EAWM years, simulated DJF surface BC concentrations in the 5 weakest monsoon years were higher by 0.13–0.15µgm−3 (5–8%) in northern China and by 0.04–0.10µgm−3 (3–12%) in southern China. The resulting JJA (DJF) mean all-sky DRF of BC at the top of the atmosphere was 0.04Wm−2 (3%; 0.03Wm−2, 2%) higher in northern China but 0.06Wm−2 (14%; 0.03Wm−2, 3%) lower in southern China. In the weakest monsoon years, the weaker vertical convection at the elevated altitudes led to the lower BC concentrations above 1–2km in southern China, and therefore the lower BC DRF in the region. The differences in vertical profiles of BC between the weakest and strongest EASM years (1998–1997) and EAWM years (1990–1996) reached up to −0.09µgm−3 (−46%) and −0.08µgm−3 (−11%) at 1–2km in eastern China.

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We applied a global 3-D CTM to examine the impacts of the East Asian summer and winter monsoons on the interannual variations of surface concentrations, vertical distributions, and direct radiative forcing of black carbon (BC) over eastern China and the mechanisms through which the monsoon influences the variations of BC. Model results from our study have important implications for guiding measures to reduce BC emissions to mitigate near-term climate warming and to improve air quality in China.
We applied a global 3-D CTM to examine the impacts of the East Asian summer and winter monsoons...
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