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
Received: 15 Apr 2016 – Discussion started: 23 May 2016
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 0.30 µg m−3 (44 %) and 0.77 µg m−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 0.04–0.09 µg m−3 (3–11 %), but lower over southern China (110–125° E, 20–27° N) by 0.03–0.04 µg m−3 (10–11 %). Compared to the 5 strongest EAWM years, simulated DJF surface BC concentrations in the 5 weakest monsoon years were higher by 0.13–0.15 µg m−3 (5–8 %) in northern China and by 0.04–0.10 µg m−3 (3–12 %) in southern China. The resulting JJA (DJF) mean all-sky DRF of BC at the top of the atmosphere was 0.04 W m−2 (3 %; 0.03 W m−2, 2 %) higher in northern China but 0.06 W m−2 (14 %; 0.03 W m−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 1–2 km 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 −0.09 µg m−3 (−46 %) and −0.08 µg m−3 (−11 %) at 1–2 km in eastern China.
Revised: 20 Mar 2017 – Accepted: 22 Mar 2017 – Published: 12 Apr 2017
Mao, Y.-H., Liao, H., and Chen, H.-S.: Impacts of East Asian summer and winter monsoons on interannual variations of mass concentrations and direct radiative forcing of black carbon over eastern China, Atmos. Chem. Phys., 17, 4799-4816, doi:10.5194/acp-17-4799-2017, 2017.