Source Attribution of Black Carbon over Himalayas and Tibetan Plateau
Black carbon particles, either airborne or deposited on snow surfaces, can cause earlier snowmelt and potentially glacier retreat in the Himalayas and on the Tibetan Plateau. Since particles are emitted from both natural and manmade sources in a number of regions, understanding where they originate and how they are generated and transported is important for developing guidance to mitigate their impact on the environment. These concerns prompted a team of U.S. Department of Energy scientists from Pacific Northwest National Laboratory and collaborators from the Key Laboratory for Semi-Arid Climate Change (Ministry of Education, China) to characterize the various means by which black carbon particles arrive on the plateau and in the mountains. The team compared simulations from the Community Atmosphere Model (CAM5 with source-tagging capability) to ground and satellite observations from the Himalayas, Tibetan Plateau, and surrounding areas. The model simulation agreed well with seasonal variations in near-surface, airborne black carbon concentrations and provided confidence in the modeling framework. The team’s analysis showed that the amount of black carbon from different regions varies according to season and location. Their estimates indicate that the largest contribution to the black carbon burden and deposition is from biofuel and biomass burning emissions in South Asia, followed by fossil fuel emissions, first from South Asia and, second, from East Asia. Local emissions in the Himalayas and on the plateau contribute only 10 percent of the black carbon in the region, but small local changes in emissions would have a big effect. These findings contribute insights into the impact of black carbon on snow and glacier melting and potential for mitigation actions.
Zhang, R., H. Wang, Y. Qian, P. J. Rasch, R. C. Easter, P.-L. Ma, B. Singh, J. Huang, and Q. Fu. 2015. “Quantifying Sources, Transport, Deposition, and Radiative Forcing of Black Carbon over the Himalayas and Tibetan Plateau,” Atmospheric Chemistry and Physics 15, 6205–23. DOI: 10.5194/acp-15-6205-2015.