Extreme firn metamorphism: impact of decades of vapor transport on near-surface firn at a low-accumulation glazed site on the East Antarctic plateau
Extreme firn metamorphism: impact of decades of vapor transport on near-surface firn at a low-accumulation glazed site on the East Antarctic plateau
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DOI：
10.3189/172756404781814041
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发表时间：
2004-06
影响因子：
2.9
通讯作者：
M. Albert;C. Shuman;Z. Courville;R. Bauer;M. Fahnestock;T. Scambos
中科院分区：
文献类型：
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作者：
M. Albert;C. Shuman;Z. Courville;R. Bauer;M. Fahnestock;T. Scambos
雪和积雪的性质控制着大气和下伏地层之间水汽、气体和水的输送。了解这种传输和控制它的属性是很重要的预测化学物质的空气-雪传输和解释冰芯。南极洲东部的遥感图像显示出大面积的明暗交替带。这些低振幅，长波长的特征有光滑的顺风面和粗糙的逆风面，被称为巨色调。本文报道了在一个明确的大范围内的釉面区域的渗透性和相关的微观结构的第一个连接的测量。渗透率和密度进行了测量，沿着与来自数字图像处理保存厚部分，在这个寒冷的，低积累的釉面网站的粒度特性。存在明显的分层模式。在顶部仪表的积雪密度范围从0.24到0.50克cm-3。渗透率的测量范围为50 x 10-10至200 x 10-10μ2，比南极洲Siple Dome等温暖、高积累地点的相应剖面大几倍。结果表明，浮力驱动的自然对流可能是很重要的沉积后的过程中非常冷，低积累的网站，这样的。
Abstract Snow and firn properties control the transport of vapor, gases and water between the atmosphere and the underlying strata. An understanding of this transport and the properties that control it is important for predicting air–snow transfer of chemical species and for interpreting ice cores. Remote-sensing images of East Antarctica show large areas of alternating light and dark bands. These low-amplitude, long-wavelength features have glazed downwind faces and rough upwind faces and are called megadunes. The first linked measurements of the permeability and the associated microstructure for a glazed area within a well-defined megadune area are reported in this paper. Permeability and density were measured, along with grain-scale properties derived from digital image processing of preserved thick sections, at this cold, low-accumulation glazed site. A clear layering pattern exists. In the top meter the firn density ranges from 0.24 to 0.50 g cm–3. Permeability measurements range from 50 x 10–10 to 200 x 10–10μ2, several times greater than corresponding profiles from warmer, higher-accumulation sites like Siple Dome, Antarctica. It is shown that buoyancy-driven natural convection may be important in post-depositional processes in very cold, low-accumulation sites like this.