In-situ measurements of light-absorbing impurities in snow of glacier on Mt. Yulong and implications for radiative forcing estimates.
In-situ measurements of light-absorbing impurities in snow of glacier on Mt. Yulong and implications for radiative forcing estimates.
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DOI：
10.1016/j.scitotenv.2017.01.032
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
H. Niu;Shi-chang Kang;Xiaofei Shi;Rukumesh Paudyal;Yuanqing He;Gang Li;Shijin Wang;T. Pu;
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文献类型：
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作者：
H. Niu;Shi-chang Kang;Xiaofei Shi;Rukumesh Paudyal;Yuanqing He;Gang Li;Shijin Wang;T. Pu;
青藏高原（TP）或第三极冰冻圈与黑碳（BC）排放的地理热点接壤。BC和灰尘在气候系统和地球的能量收支中起着重要作用，特别是在它们沉积在雪和冰川表面之后。BC和尘埃是雪和冰川中两种主要的吸光杂质（莱什）。由于青藏高原是全球地球物理研究的热点地区，因此估算青藏高原雪和冰川冰中莱什指数的浓度和分布具有重要意义。不同的雪样品，包括表面老化的雪，叠加的冰和雪融水样品收集从一个典型的温带冰川山。2015年融雪季的玉龙。使用改进的热/光反射（DRI Model 2001）方法和粉尘浓度的重量法测定样品的BC、有机碳（OC）浓度。结果表明，研究区的莱什指数具有高度的海拔依赖性。在冰川相对较低的海拔（通常低于5000 m）处观察到更高的含量和可能更多的沉积。莱什指数的时间差异表明，随着冰川融化的进行，冰川雪中的莱什指数逐渐增加。BC和灰尘的相对吸收的评估显示，灰尘对雪的反射和辐射强迫（RF）的影响是远远大于BC，特别是当灰尘含量较高。这通过吸收因子（< 1.0）得到验证。此外，我们发现，在雪融化季节，BC引起的雪中碳含量减少在2%到近10%的范围内，平均雪中碳含量减少为4.63%，因此，在一个典型的温带冰川的雪中，BC含量范围为281到894 ng g− 1。Yulong，相关的瞬时RF将为76.38-146.96 W m− 2。对冰川消融引起的莱什指数的划分还有待进一步研究，结合冰川长期原位观测的莱什指数模拟研究也是今后工作的重点。
The Tibetan Plateau (TP) or the third polar cryosphere borders geographical hotspots for discharges of black carbon (BC). BC and dust play important roles in climate system and Earth's energy budget, particularly after they are deposited on snow and glacial surfaces. BC and dust are two kinds of main light-absorbing impurities (LAIs) in snow and glaciers. Estimating concentrations and distribution of LAIs in snow and glacier ice in the TP is of great interest because this region is a global hotspot in geophysical research. Various snow samples, including surface aged-snow, superimposed ice and snow meltwater samples were collected from a typical temperate glacier on Mt. Yulong in the snow melt season in 2015. The samples were determined for BC, Organic Carbon (OC) concentrations using an improved thermal/optical reflectance (DRI Model 2001) method and gravimetric method for dust concentrations. Results indicated that the LAIs concentrations were highly elevation-dependent in the study area. Higher contents and probably greater deposition at relative lower elevations (generally < 5000 m asl) of the glacier was observed. Temporal difference of LAIs contents demonstrated that LAIs in snow of glacier gradually increased as snow melting progressed. Evaluations of the relative absorption of BC and dust displayed that the impact of dust on snow albedo and radiative forcing (RF) is substantially larger than BC, particularly when dust contents are higher. This was verified by the absorption factor, which was < 1.0. In addition, we found the BC-induced albedo reduction to be in the range of 2% to nearly 10% during the snow melting season, and the mean snow albedo reduction was 4.63%, hence for BC contents ranging from 281 to 894 ng g− 1in snow of a typical temperate glacier on Mt. Yulong, the associated instantaneous RF will be 76.38–146.96 W m− 2. Further research is needed to partition LAIs induced glacial melt, modeling researches in combination with long-term in-situ observations of LAIs in glaciers is also urgent needed in the future work.