青藏高原黑碳气溶胶外源传输及气候效应模拟研究进展与展望

青藏高原毗邻全球大气污染物排放增长最快速的地区,受西风和南亚季风的影响,中亚、南亚等高原周边排放的污染物通过大气环流传输,进入高原并对其气候环境产生重要影响。观测事实表明：近几十年青藏高原东部和南部雪冰中黑碳含量呈显著上升趋势,这可能导致冰川加速融化和积雪持续时间缩短,最终影响青藏高原的水循环过程。前人对青藏高原黑碳的外源输送,特别是南亚大气污染物的贡献及其对高原气候、冰冻圈变化的影响,还没有较清晰和统一的认识。青藏高原污染物定点监测网络的发展及高分辨率区域气候—大气化学模式的应用,为定量评估高原污染物外源输送及气候效应提供了契机。本文在国家自然科学基金青年科学基金项目“南亚黑碳气溶胶跨境传输及其对青藏高原气候影响的数值模拟研究”的资助下,在以下三个方面取得了进展：①系统性论证了高分辨率区域气候—大气化学模式在高原的适用性,模拟了青藏高原及周边区域黑碳时空分布、传输和沉降过程;②揭示了污染物扩散的机制,评估了大气黑碳的气候及雪冰效应,并对比了自然源粉尘和人为源黑碳对青藏高原气候的影响;③定量估算了不同区域排放对高原黑碳外源输送的贡献率,其中来自南亚的黑碳对青藏高原外源输送的贡献率最高,在非季风期为61.3%,季风期为19.4%。本文揭示了外源输送黑碳对青藏高原气候的影响,为提高一带一路核心区冰冻圈与水资源的管理及预测能力,制定应对环境变化策略及国家气候外交谈判提供科学依据。

Advances and prospects of research on simulating transboundary black carbon and their climatic effects over the Tibetan Plateau

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.