Notable Radiative Effects of Brown Carbon in China Haze

Abstract

Brown carbon (BrC), a light-absorbing organic aerosol, remains poorly constrained in climate models due to unclear sources and formation pathways. In this study, we developed a BrC parameterization scheme by applying multivariate regression to observational data in China, relating BrC concentrations to organic carbon, meteorological conditions, and chemical variables. This scheme was implemented into the WRF-Chem model to simulate BrC distributions and radiative effects during a haze episode from 1 January–12, 2019. The simulation revealed BrC concentrations ranging from 2.20 to 69.38 μg/m3 (mean: 11.63 μg/m3), with elevated values in the Beijing-Tianjin-Hebei region and Central China. BrC absorption notably decreased surface shortwave radiation by 7.07 W/m2 and increased atmospheric shortwave radiation by 0.73 W/m2, inducing non-negligible land surface cooling, positive pressure anomalies, and higher near-surface humidity. These findings underscore the notable radiative influence of BrC in haze-prone regions of China, with implications for local climate and atmospheric dynamics.