We quantify the contributions from five domestic emission sectors (residential, industry, transportation, energy, and biomass burning) and emissions outside of China (non-China) to concentration and direct radiative forcing (DRF) of black carbon (BC) in China for year 2010 using a nested-grid version of the global chemical transport model (GEOS-Chem) coupled with a radiative transfer model. The Hemispheric Transport of Air Pollution (HTAP) anthropogenic emissions of BC for year 2010 are used in this study. Simulated surface-layer BC concentrations in China have strong seasonal variations, which exceed 9 µg m-3 in winter and are about 1–5 µg m-3 in summer in the North China Plain and the Sichuan Basin. Residential sector is simulated to have the largest contribution to surface BC concentrations, by 5–7 µg m-3 in winter and by 1–3 µg m-3 in summer, reflecting the large emissions from winter heating and the enhanced wet deposition during summer monsoon. The contribution from industry sector is the second largest and shows relatively small seasonal variations; the emissions from industry sector contribute 1–3 µg m-3 to BC concentrations in the North China Plain and the Sichuan Basin. The contribution from transportation sector is the third largest, followed by that from biomass burning and energy sectors. The non-China emissions mainly influence the surface-layer concentrations of BC in western China; about 70% of surface-layer BC concentration in the Tibet Plateau is attributed to transboundary transport. Averaged over all of China, the all-sky DRF of BC at the top of the atmosphere (TOA) is simulated to be 1.22 W m-2. Sensitivity simulations show that the TOA BC direct radiative forcings from the five domestic emission sectors of 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. These results have important implications for taking measures to reduce BC emissions to mitigate near-term climate warming and to improve air quality in China.
