青藏高原典型冰川表面雪冰中吸光性杂质时空特征及其对冰川消融的影响

Light-absorbing impurities (LAIs, e.g., organic carbon, black carbon, and mineral dust) deposited on glacier surface can reduce the albedo and accelerate the glacier melt. Thus, LAIs in snow/ice were identified as one of the major potential factors for the glaciers retreat in the Tibetan Plateau. More than 10 big rivers in Asia originates from the Tibetan Plateau, which provides fresh water to arid regions of China and billions of people living downstream, playing an important role in the socio-economic development of the people. In this project, surface snow/ice and snowpit samples from two typical glaciers of the Tibetan Plateau will be collected. The spatiotemporal variations, transformation and enrichment of the LAIs in surface snow/ice of the glaciers will be investigated by using a long-time series and systematic field observation and laboratory analysis. For carbonaceous aerosol emissions from fires spots (open burnings), the Fire INventory from NCAR version 1.5 (FINN v1.5), speciated with the Goddard Earth Observing System-Chemical transport model (GEOS-Chem), will be used to determine organic carbon and black carbon emissions attributable to open burnings. Furthermore, the SNow ICe Aerosol Radiative (SNICAR) model will be used to simulate the effects of LAIs on snow/ice albedo reduction. Based on the glacier melt Model, the effects of LAIs on Tibetan Plateau glaciers melting will be quantitatively evaluated. Overall, our study has a great significance to the rapid glacier melting over the Tibetan Plateau and provides a theoretical support to mitigate emissions from anthropogenic carbonaceous aerosols.

沉降在冰川表面的吸光性杂质（如有机碳、黑碳、矿物粉尘等）是降低雪冰反照率和加速雪冰消融不可忽视的重要因素，被认为是加速青藏高原冰川消融的潜在影响因子之一。蕴藏于青藏高原的冰川是亚洲十大河流的发源地，也是我国干旱区最直接的水源，对当地社会经济发展起着举足轻重的作用。本项目拟在青藏高原中部和南部选取两条典型冰川，通过长期、系统地实地观测和实验室分析，获取冰川表面雪冰中吸光性杂质含量的时空分布特征及其迁移、富集过程；利用全球火点排放清单FINN v1.5和GEOS-Chem机制确定其排放的含碳气溶胶在冰川区的沉降贡献率；利用SNICAR模型量化吸光性杂质对雪冰表面反照率降低的影响，结合雪冰消融模型，定量评估其对青藏高原冰川消融的影响。该项目对青藏高原冰川快速消融研究具有重要意义，也为人为源含碳气溶胶的减排提供理论支撑。

广袤的青藏高原，不同区域雪冰中吸光性气溶胶沉降量存在着巨大差别，对冰川消融的影响程度和强度也明显不同，尤其在消融期吸光性杂质的含量差异极大。本项目在青藏高原典型冰川（小冬克玛底冰川和扎当冰川），通过长期、系统地实地观测和实验室分析，认识研究冰川表面雪冰中吸光性杂质的含量、时空分布特征，并探讨其变化因素；通过全球火排放清单FINN v1.5和GEOS-Chem机制分析其排放的含碳气溶胶在冰川区的沉降贡献率；通过SNICAR模型和雪冰消融模型分析吸光性杂质对反照率、辐射强迫和冰川消融的影响。项目取得的主要成果包括：1）获得青藏高原典型冰川表面雪冰中吸光性杂质的含量及分布特征；2）计算了源自于FINN v1.5全球火点排放清单中火点排放的黑碳在小冬克玛底冰川和扎当冰川沉降的贡献率；3）计算了黑碳和矿物粉尘对青藏高原典型冰川反照率、辐射强迫和冰川消融的影响；4）将研究冰川扩展到青藏高原东南地区和南部地区，获得了冰川表面雪冰中水溶性有机碳的含量及其光学特性。在项目的支持下，发表SCI论文5篇，中文核心期刊1篇，包括Journal of Glaciology和Science of the Total Environment等冰川学和环境科学权威期刊。培养博士研究生3名，硕士生1名，项目组项目负责人晋升为副教授。项目的实施提升了青藏高原冰川雪冰中吸光性杂质的来源、传输、分布、演化以及对冰川消融影响的认知水平，为青藏高原冰川的变化提供参考和依据，并为人为源含碳气溶胶的减排提供理论支撑。