Influence of Brown Carbon Aerosol Deposition on Snow Surface Reflection Spectra

Brown carbon (BrC) is a form of organic carbon emitted from combustion processes with a brownish or yellowish visual appearance, caused by enhanced light absorption at shorter visible and ultraviolet wavelengths. Recently, optical properties of BrC aerosols have become the topic of intense research, but little is known about how BrC deposition onto snow surfaces affects the snow albedo spectrum and the resulting radiative forcing. We generated BrC through small-scale, smoldering biomass combustion and deposited it onto natural snow surfaces in the Carson Range of the Sierra Nevada, USA. After deposition, we monitored the spectral reflectivity of these disturbed snow surfaces and of adjacent undisturbed snow surfaces and observed a strong reduction of snow surface reflectivity in the blue and ultraviolet spectral regions. We also will discuss (1) the temporal evolution of the snow surface reflectivity after BrC deposition, (2) modeling results for the influence of deposited BrC on snow surface albedo, and (3) BrC-on-snow radiative forcing.