Sensitivity of Black Carbon Deposition in Snow and Radiative Forcing in the Arctic and Northern China

1. Impurities in Snow and its Radiative Forcing over the Arctic and Northern China Objective • To understand the sensitivity and uncertainty of light absorbing aerosols deposition and the snow-melting process in current Earth system models Sensitivities of black carbon in snow concentration (top) and radiative forcing (bottom) to uncertain parameters. • Approach • Evaluate simulated black carbon (BC) in snow against measurements from multiple field campaigns over the Arctic and Northern China • Conduct sensitivity experiments in CAM5 to examine the impacts of snow-aging and melt-water scavenging (MSE) efficiency on snow-melting and radiative forcing of BC • Compare BC deposition uncertainty with that related to the treatment of snow-aging and melt-water scavenging for BC Impact • Improvements in atmospheric BC transport and deposition significantly reduce the biases (by a factor of two) in the estimation of BC concentration over both Northern China and the Arctic • Melt-water scavenging efficiency parameter found to play important role in regulating BC concentrations and radiative forcing. Qian Y, H Wang, R Zhang, M Flanner, and PJ Rasch. 2014. “A Sensitivity Study on Modeling the Black Carbon in Snow and its Radiative Forcing over the Arctic and Northern China.” Environmental Research Letters 9(6):064001. DOI:10.1088/1748-9326/9/6/064001