Black Carbon and Dust Radiative Forcing in Seasonal Snow: A Case Study over North China
On a large scale, snow regulates the temperature of Earth’s surface and alters the general circulation of the climate. At a smaller scale, it affects regional climate and water resources. Light-absorbing particles, primarily black carbon (BC), brown carbon, and dust, impact how well the snow reflects light, thereby influencing Earth’s albedo. Researchers, led by scientists at the Department of Energy’s Pacific Northwest National Laboratory, used a regional modeling framework to simulate BC and dust and their direct radiative forcing in snowpack. They found that the simulations are consistent in spatial variability with observations for black carbon and dust mass concentrations (BCS and DSTS, respectively) in the top snow layer, while they underestimate BCS in clean regions and overestimate BCS in some polluted regions. BCS and DSTS result in a similar magnitude of radiative warming in the snowpack, which is comparable to the amount of surface radiative cooling due to BC and dust in the atmosphere. To produce the simulations, the research used the Weather Research and Forecasting (WRF) model, a state-of-the-art regional model with a chemistry component. They coupled it with the snow, ice, and aerosol radiative (SNICAR) model that includes the most sophisticated representation of snow metamorphism processes available for climate study. The coupled model simulated black carbon and dust concentrations and their radiative forcing in seasonal snow over North China in January through February 2010, with extensive field measurements used to evaluate the model performance. The findings highlight a need for more observations, particularly concurrent measurements of atmospheric and snow aerosols and the deposition aerosol fluxes, in future campaigns.
Zhao, C., Z. Hu, Y. Qian, R. Leung, J. Huang, M. Huang, J. Jin, M. Flanner, R. Zhang, H. Wang, H. Yan, Z. Lu, and D. G. Streets. 2014. “Simulating Black Carbon and Dust and Their Radiative Forcing in Seasonal Snow: A Case Study over North China with Field Campaign Measurements,” Atmospheric Chemistry and Physics 14, 11475–491. DOI: 10.5194/acp-14-11475-2014.