Measurement of the specific surface area of 176 snow samples using methane adsorption at 77 K -: art. no. 4335
Measurement of the specific surface area of 176 snow samples using methane adsorption at 77 K -: art. no. 4335
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DOI：
10.1029/2001jd001016
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发表时间：
2002-09-01
影响因子：
4.4
通讯作者：
Dominé, F
中科院分区：
文献类型：
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作者：
Legagneux, L;Cabanes, A;Dominé, F
为了帮助量化大气和积雪之间的交换，我们测量了 176 个雪样的比表面积 (SSA)，这些雪样取自阿尔卑斯山、斯瓦尔巴群岛和加拿大阿勒特周围高纬度地区的季节性积雪。采用容量法，记录77 K下CH4在雪上的吸附等温线。通过 Brunauer-Emmett-Teller 方法分析数据，得出 SSA 和 DeltaQ(CH4)，即第一 CH4 单层的平均吸附热。获得的 SSA 值在 100 至 1580 cm(2)/g 之间。该方法的重现性估计为 6%，准确度估计为 12%。我们建议使用 DeltaQ(CH4)=2240+/-200 J/mol 作为测量可靠性的标准。详细描述该方法以促进其使用。陈化的雪样的 SSA 比新鲜的雪样低。多面晶体和深度灰白的值最低，新鲜的有缘树枝状雪的值最高。建议现场调查人员使用一种方法，通过对雪的目视检查和密度测量来估计 SSA。根据雪龄和晶体形状，雪样分为 14 种类型。在每种类型中，确定密度与 SSA 的相关性。我们的数据表明，根据雪的类型，使用所提出的方法可以在 1sigma 置信水平下将 SSA 估计在 25% 至 40% 范围内。初步数据表明，给定雪层的 SSA 空间变异性较低（
To help quantify exchanges between the atmosphere and the snow cover, we have measured the specific surface area (SSA) of 176 snow samples taken from the seasonal snowpack in the Alps, Svalbard, and the Canadian high Arctic around Alert. A volumetric method was used, and the adsorption isotherm of CH4 on snow at 77 K was recorded. The data were analyzed by the Brunauer-Emmett-Teller method to yield SSA and DeltaQ(CH4), the mean heat of adsorption of the first CH4 monolayer. SSA values obtained were between 100 and 1580 cm(2)/g. The reproducibility of the method is estimated at 6%, and the accuracy is estimated at 12%. We propose that DeltaQ(CH4)=2240+/-200 J/mol should be used as a criterion of reliability of the measurement. The method is described in detail to promote its use. Aged snow samples have lower SSA than fresh ones. The lowest values were found for faceted crystals and depth hoar, and the highest values were found for fresh rimed dendritic snow. A method that field investigators can use to estimate SSA from a visual examination of the snow and from a density measurement is suggested. Snow samples are classified into 14 types based on snow age and crystal shapes. Within each type, a density versus SSA correlation is determined. Our data indicate that, depending on snow type, SSA can then be estimated within 25 to 40% at the 1sigma confidence level with the method proposed. Preliminary data suggest that SSA spatial variability of a given snow layer is low (