Abstract:

The Tibetan Plateau is surrounded by regions of the fastest growing atmospheric pollutants. The westerlies and the South Asian monsoon circulation transport the pollutants from Central Asia and South Asia to the inland of the Tibetan Plateau, which have important effects on the regional climate and environment. The concentration of black carbon in the snow and ice showed a clearly increasing trend during the recent few decades in the eastern and southern Tibetan Plateau, which might be associated with accelerated melting of snow and glaciers, and directly affected the hydrological processes on the plateau. However, the amount of transboundary transport of black carbon from South Asia is not clear and the knowledge of its impact on climate and cryosphere over the Tibetan Plateau is still limited. The development of atmospheric pollutants monitoring network on the Tibetan Plateau and the application of the high-resolution regional climate-atmospheric chemistry coupled model provide an opportunity for quantitative assessment of external transported pollutants and their climatic effects on the plateau. The project of “Simulation of transboundary transport of black carbon from South Asia and its impact on climate over the Tibetan Plateau,” which was supported by the National Natural Science Foundation of China, focused on the following three aspects: (1) Systematic assessment of the high-resolution regional climate-atmospheric chemistry coupled model performance in the simulation for the Tibetan Plateau. Based on the simulation of distribution, transportation, and deposition processes of black carbon over the Tibetan Plateau and surrounding regions, the climatic effects were investigated; (2) Examination of the mechanism of pollutant diffusion , and evaluation and comparison of the climatic effects induced by the anthropogenic and natural sources; (3) Quantitative estimation of the contribution of external pollutants outside the Tibetan Plateau. The results show that the black carbon from South Asia provided the highest contribution, which was 61.3% in the non-monsoon period and 19.4% in the monsoon season. This study revealed the effect of transboundary black carbon on the Tibetan Plateau, which may provide a scientific basis for improved management and prediction of the cryosphere and water resources in the core region of the Belt and Road initiative, and for police-making of climate change adaption and diplomatic negotiations.

Key words: black carbon, transportation, climatic effects, Tibetan Plateau