10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A New Method for the Determination of BC Mass Concentration from Light Absorption
YINGLI YU, Chunsheng Zhao, Wangshu Tan, Peking University
Abstract Number: 1071 Working Group: Carbonaceous Aerosol
Abstract Atmospheric black carbon (BC) is the strongest visible solar radiative absorber in the atmosphere, exerting significant influences on the earth’s radiation budget. The mass absorption cross-section (MAC), describing the light absorption ability per unit mass, is a crucial parameter for the conversion of light absorption coefficient to mass equivalent BC concentrations. MAC is influenced by many factors such as aerosol mixing state, BC core size and aerosol refractive index. However, MAC is a constant for the filter-based measurements to calculate BC mass concentration, introducing significant uncertainties. In this paper, we develop a look-up table of MAC, BC core size and particle size. An iterative algorithm for the conversion of light absorption coefficient to BC mass concentration is proposed by considering the influences of BC mixing state and BC core size on MAC. The results show that AE33(widely used filter-based instrument) underestimates the BC mass loading by 35% for aerosol particles smaller than 270nm and overestimates the BC mass loading by 20% for aerosol particles larger than 270nm. This work deepens our understanding in the influences of mixing state on BC optical properties and is helpful for the uncertainty constraining of BC mass concentration measurements.