Investigating the Emission and Optical Properties of Brown Carbon Aerosol using both Field Measurements and Global Model Simulations

Wednesday, 17 December 2014
Xuan Wang, Massachusetts Institute of Technology, Cambridge, MA, United States and Colette L Heald, Massachusetts Institute of Technology, Civil and Environmental Engineering, Cambridge, MA, United States
Brown carbon (BrC), is the component of organic aerosols (OA) which strongly absorbs solar radiation in the near-UV range of the spectrum. However the source, evolution, and optical properties of BrC remain highly uncertain. BrC absorption exhibits strong spectral dependence, which differs from black carbon (BC), the other important absorber in fine aerosols. As a result, multiple wavelengths absorption measurements of aerosols offer constraints on BrC abundance. In this study, we synthesize the multi-wavelength absorption measurements from a suite of field campaigns and derive the BrC absorption. By comparing with the co-measured BC, OA mass and aerosol extinction, we analyze the relationship between BrC absorption and these factors. We then use a global GEOS-Chem model simulation to test these relationships, and estimate the emission and optical properties of BrC in diverse regions. The global burden and direct radiative forcing (DRF) of BrC are also investigated based on our model simulations.