An AeroCom Assessment of Black Carbon in Arctic Snow and Sea Ice

Though many global aerosols models prognose surface deposition, only a few models have been used to di- rectly simulate the radiative effect from black carbon (BC) deposition to snow and sea ice. Here, we apply aerosol de- position fields from 25 models contributing to two phases of the Aerosol Comparisons between Observations and Mod- els (AeroCom) project to simulate and evaluate within-snow BC concentrations and radiative effect in the Arctic. We ac- complish this by driving the offline land and sea ice com- ponents of the Community Earth System Model with dif- ferent deposition fields and meteorological conditions from 2004 to 2009, during which an extensive field campaign of BC measurements in Arctic snow occurred. We find that models generally underestimate BC concentrations in snow in northern Russia and Norway, while overestimating BC amounts elsewhere in the Arctic. Although simulated BC distributions in snow are poorly correlated with measure- ments, mean values are reasonable. The multi-model mean (range) bias in BC concentrations, sampled over the same grid cells, snow depths, and months of measurements, are 4.4 ( 13.2 to +10.7) ng g 1 for an earlier phase of Aero- Com models (phase I), and +4.1 ( 13.0 to +21.4) ng g 1