Model analysis of long-term trends of aerosol burdens and direct radiative forcings over East Asia
- Publisher: Tellus B
climate change; atmospheric chemistry; aerosol science | Aerosol burden; Aerosol direct radiative forcing; inter-decadal trend; East Asia; eastern China; Model simulation
Long-term trends of aerosol concentrations and direct radiative forcings in East Asia have been investigated by adopting an online-coupled regional climate-chemistry-aerosol model (RIEMS-Chemaero) and the IPCC AR5 (the Intergovernmental Panel on Climate Change Fifth Assessment Report) emission inventory with the focus on eastern China. Model evaluation against surface observations of aerosol components demonstrates that the model can reproduce the spatial distribution and temporal variation of aerosol components generally well but tends to under-predict aerosol magnitudes especially for carbonaceous aerosols. Model comparison with aerosol optical depth (AOD) from both satellite retrieval and surface measurement shows that the model is capable of reproducing the distribution feature of AOD reasonably well but tends to under-predict magnitude. North of eastern China and the Sichuan basin are high concentration centres for near-surface anthropogenic aerosols. The domain averaged column burden of inorganic aerosol over East Asia increased from 1850 to 2010 with the peak in 1990 (18.7mg m-2), whereas that in eastern China peaked in 2010 (32.9 mg m-2). The burden of carbonaceous aerosol peaked in 1980 (5.2 mg m-2) in East Asia, but it peaked in 1990 (7.1 mg m-2) in eastern China and then decreased thereafter. Both inorganic and carbonaceous aerosol burdens showed little change during 1990-2000 due to effective emission control in China. AOD values over eastern China increased almost continuously from 1850 to 2010 with the Sichuan basin the high AOD centre. All-sky aerosol direct radiative forcing at the surface (ADRFSRF) is negative over all of East Asia, while radiative forcing at the top of the atmosphere (ADRFTOA) is negative over eastern China but positive over west China. Domain and annual mean ADRFSRF in East Asia peaked in 2000 (–11.9W m-2), but that in eastern China peaked in 2010 (–17.5 W m-2). Mean ADRFTOA became negative since 1970 and showed the strongest forcing in 1990 (– 2.9 W m-2) for East Asia and in 2010 (– 4.8 W m-2 ) for eastern China. Sensitivity simulation shows that anthropogenic emission change plays the dominant role in the variation of aerosol concentration and direct radiative forcing in this region. Keywords: aerosol concentration and burden, direct radiative forcing, interannual trend, East Asia, eastern China, model simulation(Published: 13 September 2013)Citation: Tellus B 2013, 65, 20410, http://dx.doi.org/10.3402/tellusb.v65i0.20410Access the supplementary material to this article – see Supplementary files under Article Tools online.