Snow albedo reduction in seasonal snow due to anthropogenic dust and carbonaceous aerosols across northern China

Abstract

A survey was performed to collect 92 seasonal snow samples across northern China in January 2014. The results show that mixing ratios of black carbon (BC), organic carbon (OC), and anthropogenic dust (AD) range from 60 to 4200 ng g −1, 280 to 32 000 ng g −1, and 1300 to 5800 ng g −1 in surface snow, respectively. A relatively high correlation (R 2 = 0.87, n = 13) between OC and BC in surface snow is observed, indicating similar emission sources, and high OC/BC ratios suggest that biomass burning may be a major contributor at most snow sampling sites. In addition to the BC and AD parameters in the Snow, Ice, and Aerosol Radiation (SNICAR) model, the OC content in snow is considered an initial parameter for calculating snow albedo through a new radiative transfer model (Spectral Albedo Model for Dirty Snow, or SAMDS). The spectral albedo of snow reduction caused by OC (20 μg g −1) is up to a factor of 3 for a snow grain size of 800 μm compared to 100 μm. We find a larger difference in snow albedo levels between the model simulations and surface measurements for higher insoluble light-absorbing impurities (ILAPs) using the measured snow grain radii. However, using the optical effective radii (R eff), snow albedos modeled through both the SNICAR and SAMDS models are consistent with surface measurements, especially in the case of near-infrared wavelengths.