School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
Proc Natl Acad Sci U S A. 2012 Jul 17;109(29):11624-9. doi: 10.1073/pnas.1203707109. Epub 2012 Jul 2.
Carbonaceous aerosols (CA) emitted by fossil and biomass fuels consist of black carbon (BC), a strong absorber of solar radiation, and organic matter (OM). OM scatters as well as absorbs solar radiation. The absorbing component of OM, which is ignored in most climate models, is referred to as brown carbon (BrC). Model estimates of the global CA radiative forcing range from 0 to 0.7 Wm(-2), to be compared with the Intergovernmental Panel on Climate Change's estimate for the pre-Industrial to the present net radiative forcing of about 1.6 Wm(-2). This study provides a model-independent, observationally based estimate of the CA direct radiative forcing. Ground-based aerosol network data is integrated with field data and satellite-based aerosol observations to provide a decadal (2001 through 2009) global view of the CA optical properties and direct radiative forcing. The estimated global CA direct radiative effect is about 0.75 Wm(-2) (0.5 to 1.0). This study identifies the global importance of BrC, which is shown to contribute about 20% to 550-nm CA solar absorption globally. Because of the inclusion of BrC, the net effect of OM is close to zero and the CA forcing is nearly equal to that of BC. The CA direct radiative forcing is estimated to be about 0.65 (0.5 to about 0.8) Wm(-2), thus comparable to or exceeding that by methane. Caused in part by BrC absorption, CAs have a net warming effect even over open biomass-burning regions in Africa and the Amazon.
碳质气溶胶 (CA) 由化石和生物质燃料排放，由黑碳 (BC) 和有机物 (OM) 组成，BC 是太阳辐射的强吸收体，OM 既散射又吸收太阳辐射。OM 的吸收成分在大多数气候模型中被忽略，被称为棕色碳 (BrC)。模型估计全球 CA 的辐射强迫范围从 0 到 0.7 Wm(-2)，与政府间气候变化专门委员会对工业化前到现在的净辐射强迫的估计值 1.6 Wm(-2)相比。本研究提供了一种基于模型独立的 CA 直接辐射强迫的观测基础的估计。地面气溶胶网络数据与现场数据和卫星气溶胶观测相结合，提供了一个十年 (2001 年至 2009 年) 的全球 CA 光学特性和直接辐射强迫的视图。估计的全球 CA 直接辐射效应约为 0.75 Wm(-2) (0.5 到 1.0)。本研究确定了 BrC 的全球重要性，表明其对全球 550nm CA 太阳吸收的贡献约为 20%到 55%。由于 BrC 的纳入，OM 的净效应接近零，CA 强迫几乎等于 BC 的强迫。CA 的直接辐射强迫估计约为 0.65 (0.5 到约 0.8) Wm(-2)，因此与甲烷相当或超过甲烷。部分由于 BrC 的吸收，CA 即使在非洲和亚马逊的开放生物质燃烧地区也具有净变暖效应。
