Light absorption properties of brown carbon are overestimated by neglecting dust absorption

Accurate quantification of the light absorption properties of brown carbon (BrC) aerosols is crucial to assess the climatic impacts of BrC. However, the light absorption properties of BrC were often misestimated in field observations, due to neglecting the contribution of dust absorption. This study solved this problem by coupling a new method for calculating the dust concentration into the traditional method for quantifying BrC absorption. The negative effect of dust was successfully excluded when quantifying BrC light absorption properties at a northwestern Chinese site. The comparison results showed that the traditional method severely overestimated the absorption of BrC components due to the lack of constraints of dust information. Neglecting dust absorption could overestimate the direct radiative forcing of BrC absorption by ~30% at the site. This work can be used to adjust the optical parameters of BrC in climate models, prompting us to revisit the real climate effects of BrC.