Characterization and light absorption of Brown Carbon in Sichuan Basin, Southwestern China: Impacts of biomass burning and secondary formation

Brc Carbon is a class of light-absorbing organic species, playing important roles on solar radiation budget and therefore influences climate forcing over regional and even global scales. We analyzed and evaluated the light absorption and radiative forcing of BrC in Chongqing, Wanzhou (Three Gorges Reservoir region), and Chengdu in the Sichuan Basin of Southwest China. The light-absorbing properties were evaluated, including mass absorption efficiency, absorption Ångström exponent, and contributions to radiative forcing. The sources of BrC are also identified, including the contribution of secondary aerosol formation and primary emissions. This study contributes to the understandings of sources and the impact of brown carbon in the Sichuan Basin, southwestern China.