State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China.
Sci Total Environ. 2017 Jun 1;587-588:482-490. doi: 10.1016/j.scitotenv.2017.02.169. Epub 2017 Feb 28.
Light-absorbing impurities (LAIs), such as organic carbon (OC), black carbon (BC), and mineral dust (MD) deposited on the glacier surface can reduce albedo, thus accelerating the glacier melt. Surface fresh snow, aged snow, granular ice, and snowpits samples were collected between August 2014 and October 2015 on the Xiao Dongkemadi (XDKMD) glacier (33°04'N, 92°04'E) in the central Tibetan Plateau (TP). The spatiotemporal variations of LAIs concentrations in the surface snow/ice were observed to be consistent, differing mainly in magnitudes. LAIs concentrations were found to be in the order: granular ice>snowpit>aged snow>fresh snow, which must be because of post-depositional effects and enrichment. In addition, more intense melting led to higher LAIs concentrations exposed to the surface at a lower elevation, suggesting a strong negative relationship between LAIs concentrations and elevation. The scavenging efficiencies of OC and BC were same (0.07±0.02 for OC, 0.07±0.01 for BC), and the highest enrichments was observed in late September and August for surface snow and granular ice, respectively. Meanwhile, as revealed by the changes in the OC/BC ratios, intense glacier melt mainly occurred between August and October. Based on the SNow ICe Aerosol Radiative (SNICAR) model simulations, BC and MD in the surface snow/ice were responsible for about 52%±19% and 25%±14% of the albedo reduction, while the radiative forcing (RF) were estimated to be 42.74±40.96Wm and 21.23±22.08Wm, respectively. Meanwhile, the highest RF was observed in the granular ice, suggesting that the exposed glaciers melt and retreat more easily than the snow distributed glaciers. Furthermore, our results suggest that BC was the main forcing factor compared with MD in accelerating glacier melt during the melt season in the Central TP.
吸光性杂质（LAIs），如沉积在冰川表面的有机碳（OC）、黑碳（BC）和矿物尘（MD），可以降低反照率，从而加速冰川融化。2014 年 8 月至 2015 年 10 月，在青藏高原中部的肖东克玛迪（XDKMD）冰川（33°04'N，92°04'E）上采集了表面新雪、陈雪、粒雪和雪坑样品。观察到表面雪/冰中 LAIs 浓度的时空变化是一致的，主要区别在于大小。LAIs 浓度的顺序为：粒雪>雪坑>陈雪>新雪，这一定是由于后沉积效应和富集作用。此外，更强烈的融化导致海拔较低的表面暴露了更高的 LAIs 浓度，表明 LAIs 浓度与海拔呈强烈负相关。OC 和 BC 的清除效率相同（OC 为 0.07±0.02，BC 为 0.07±0.01），表面雪和粒雪的最高富集分别出现在 9 月下旬和 8 月。同时，根据 OC/BC 比值的变化，强烈的冰川融化主要发生在 8 月至 10 月之间。根据 SNow ICe Aerosol Radiative（SNICAR）模型模拟，表面雪/冰中的 BC 和 MD 分别导致约 52%±19%和 25%±14%的反照率降低，而辐射强迫（RF）估计分别为 42.74±40.96Wm 和 21.23±22.08Wm。同时，粒雪中的 RF 最高，表明暴露的冰川比分布的雪冰川更容易融化和退缩。此外，我们的结果表明，在青藏高原中部融季，BC 是加速冰川融化的主要驱动力，而不是 MD。
