气候变化领域集成服务门户(CCPortal): Black carbon in snow in the upper Himalayan Khumbu Valley, Nepal: Observations and modeling of the impact on snow albedo, melting, and radiative forcing

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DOI	10.5194/tc-9-1685-2015
	Black carbon in snow in the upper Himalayan Khumbu Valley, Nepal: Observations and modeling of the impact on snow albedo, melting, and radiative forcing
	Jacobi H.-W.; Lim S.; Ménégoz M.; Ginot P.; Laj P.; Bonasoni P.; Stocchi P.; Marinoni A.; Arnaud Y.
发表日期	2015
ISSN	19940416
卷号	9 期号:4
英文摘要	Black carbon (BC) in snow in the Himalayas has recently attracted considerable interest due to its impact on snow albedo, snow and glacier melting, regional climate and water resources. A single particle soot photometer (SP2) instrument was used to measure refractory BC (rBC) in a series of surface snow samples collected in the upper Khumbu Valley, Nepal between November 2009 and February 2012. The obtained time series indicates annual cycles with maximum rBC concentrations before the onset of the monsoon season and fast decreases during the monsoon period. Detected concentrations ranged from a few up to 70 ppb with rather large uncertainties due to the handling of the samples. Detailed modeling of the snowpack, including the detected range and an estimated upper limit of BC concentrations, was performed to study the role of BC in the seasonal snowpack. Simulations were performed for three winter seasons with the snowpack model Crocus, including a detailed description of the radiative transfer inside the snowpack. While the standard Crocus model strongly overestimates the height and the duration of the seasonal snowpack, a better calculation of the snow albedo with the new radiative transfer scheme enhanced the representation of the snow. However, the period with snow on the ground without BC in the snow was still overestimated between 37 and 66 days, which was further diminished by 8 to 15 % and more than 40 % in the presence of 100 or 300 ppb of BC. Compared to snow without BC, the albedo is reduced on average by 0.027 and 0.060 in the presence of 100 and 300 ppb BC. While the impact of increasing BC in the snow on the albedo was largest for clean snow, the impact on the local radiative forcing is the opposite. Here, increasing BC caused an even larger impact at higher BC concentrations. This effect is related to an accelerated melting of the snowpack caused by a more efficient metamorphism of the snow due to an increasing size of the snow grains with increasing BC concentrations. The melting of the winter snowpack was shifted by 3 to 10 and 17 to 27 days during the three winter seasons in the presence of 100 and 300 ppb BC compared to clean snow, while the simulated annual local radiative forcing corresponds to 3 to 4.5 and 10.5 to 13.0 W m-2. An increased sublimation or evaporation of the snow reduces the simulated radiative forcing, leading to a net forcing that is lower by 0.5 to 1.5 W m-2, while the addition of 10 ppm dust causes an increase of the radiative forcing between 2.5 and 3 W m-2. According to the simulations, 7.5 ppm of dust has an effect equivalent to 100 ppb of BC concerning the impact on the melting of the snowpack and the local radiative forcing. © Author(s) 2015.
学科领域	albedo; annual cycle; black carbon; climate modeling; concentration (composition); cryosphere; ecological impact; melting; observational method; radiative forcing; radiative transfer; regional metamorphism; snow; snowpack; time series; Himalayas; Khumbu Valley; Nepal; Sagarmatha [(ADS) Nepal]; Crocus
语种	英语
scopus关键词	albedo; annual cycle; black carbon; climate modeling; concentration (composition); cryosphere; ecological impact; melting; observational method; radiative forcing; radiative transfer; regional metamorphism; snow; snowpack; time series; Himalayas; Khumbu Valley; Nepal; Sagarmatha [(ADS) Nepal]; Crocus
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119832
作者单位	Laboratoire de Glaciologie et Géophysique de l'Environnement, Univ. Grenoble Alpes, Grenoble, France; Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS, Grenoble, France; Observatoire des Sciences de l'Univers de Grenoble, Univ. Grenoble Alpes, Grenoble, France; Observatoire des Sciences de l'Univers de Grenoble, IRD, Grenoble, 38000, France; CNR, ISAC-Institute of Atmospheric Sciences and Climate, Bologna, Italy; EV-K2-CNR Committee, Bergamo, Italy; Laboratoire d'étude des Transferts en Hydrologie et Environnement, Univ. Grenoble Alpes, Grenoble, France; Laboratoire d'étude des Transferts en Hydrologie et Environnement, IRD, Grenoble, France; Institut Català de Ciències del Clima - IC3, Barcelona, Spain
推荐引用方式 GB/T 7714	Jacobi H.-W.,Lim S.,Ménégoz M.,et al. Black carbon in snow in the upper Himalayan Khumbu Valley, Nepal: Observations and modeling of the impact on snow albedo, melting, and radiative forcing[J],2015,9(4).
APA	Jacobi H.-W..,Lim S..,Ménégoz M..,Ginot P..,Laj P..,...&Arnaud Y..(2015).Black carbon in snow in the upper Himalayan Khumbu Valley, Nepal: Observations and modeling of the impact on snow albedo, melting, and radiative forcing.Cryosphere,9(4).
MLA	Jacobi H.-W.,et al."Black carbon in snow in the upper Himalayan Khumbu Valley, Nepal: Observations and modeling of the impact on snow albedo, melting, and radiative forcing".Cryosphere 9.4(2015).