Source sector and region contributions to concentration and direct radiative forcing of black carbon in China

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1 Source sector and region contributions to concentration and direct radiative forcing of black carbon in China Ke Li, Hong Liao*, Yuhao Mao Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS) D. A. Ridley Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA IGC7, May 4-7,

2 Motivations Our scientific question is: Bond et al. (JGR, 2013) To quantify the contributions from the major emission sectors in China and non-china emissions to concentration and DRF of BC in China.

3 BC emission inventories in China Reference year energy Industry Residential Transportation Biomass Total burning Zhang et al. (2009) (2%) 575 (32%) 1002 (55%) 198 (11%) N.A Wang et al. (2012) Lu et al., 2011 Qin and Xie, 2012 Lu et al., (3%) 646 (33%) 988 (51%) 188 (10%) 78 (4%) (1%) 510 (29%) 888 (50%) 259 (15%) 110 (6%) (1%) 735 (40%) 777 (41%) 241 (13%) 117 (6%) (1%) 501 (27%) 936 (51%) 283 (15%) 109 (6%) 1850 HTAP (1%) 550 (30%) 893 (49%) 270 (15%) 109 (6%)* 1840 Unit:Gg C yr -1 HTAP (Janssens-Maenhout et al., 2015, ACPD): the Task Force on Hemispheric Transport of Air Pollution project (Emissions of HTAP in Asia based on MICS-Asia) * Biomass burning emissions used here are from Lu et al. (2011)

4 Simulation experiments GEOS-Chem model, v , nested over Asia ( ) All simulations with GEOS-5 meteorology for year 2010 RRTMG coupled with GEOS-Chem (Heald and Ridley et al., ACP, 2014) Experiments BC emissions (1) CTRL The control simulation with all global BC emissions from all sectors (2) no_ind Same as CTRL, but BC emissions from industry are set to zero in China (3) no_eng Same as CTRL, but BC emissions from energy are set to zero in China (4) no_res Same as CTRL, but BC emissions from residential are set to zero in China (5) no_tras Same as CTRL, but BC emissions from transportation are set to zero in China (6) no_biob (7) no_china Same as CTRL, but BC emissions from biomass burning are set to zero in China Same as CTRL, but all BC emissions in China are set to zero

5 Model evaluation: surface BC concentrations Annual mean NMB = 31% r = 0.65

6 Model evaluation: BC absorption AOD Comparison of simulation AAOD vs. observation 10 sites retrieved BC absorption AOD are from AERONET, following the method of Bond et al. (2013)

7 Contributions to surface BC concentrations (μg m -3 ) DJF MAM JJA SON Residential Industry Energy Transportation Biomass burning Non-China

8 Simulated all-sky BC DRF at TOA Simulated BC DRF over China is 1.22 W m -2. Simulated BC DRF shows large seasonal and spatial variations. Over eastern China and Sichuan Basin, high DRF reaches 8 10 W m -2 in winter.

9 Contributions to BC DRF (W m -2 ) TOA BC DRF from residential, industry, energy, transportation, biomass burning, and non-china emissions are 0.44, 0.27, 0.01, 0.12, 0.04, and 0.30 W m -2, respectively, The domestic and non- China emissions contribute 75% and 25% to BC DRF in China, respectively. Trans-boundary transport in spring is the largest contributor for BC DRF in China

10 Contributions to BC DRF over different regions (%) DJF MAM JJA SON

11 Summary Residential sector has the largest contribution to surface BC, by 5 7 µg m -3 in winter and by 1 3 µg m -3 in summer; Industry contributes 1 3 µg m - 3 to BC concentrations; BC DRF over China is 1.22 W m -2 ; domestic and non-china emissions account for 75% and 25%, respectively. These results have important implications for taking reduction measures to mitigate near-term climate warming and to improve air quality in China. Atmos. Environ. (under revision)

12 Percent contributions from non-china emissions to vertical mass concentrations of BC