In situ measurements of Antarctic snow compaction compared with predictions of models
In situ measurements of Antarctic snow compaction compared with predictions of models
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DOI：
10.1029/2009jf001306
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发表时间：
2010-07-29
影响因子：
3.9
通讯作者：
Thomas, Elizabeth R.
中科院分区：
文献类型：
--
作者：
Arthern, Robert J.;Vaughan, David G.;Thomas, Elizabeth R.
我们描述了在现场测量南极雪的压实。在南极洲的三个不同地点，在长达两年的时间里，每小时测量不同深度间隔的压实率。这些测量结果表明，压实在每个网站发生通过缓慢，粘性变形的积雪，没有显着的贡献，从突然崩溃的薄弱层。在最冷的网站测得的压实率表现出很强的季节性，与温度相关的烧结机制具有70 kJ mol（-1）的活化能一致。在两个较温暖的网站，80和120 kJ mol（-1）的活化能提供稍好的协议与观察。已发表的积雪压实模型低估了温度敏感性。一个很好的匹配，我们的观察是由一个半经验模型，基于速率方程的晶格扩散（Nabarro-Herring）蠕变孔隙周围的材料，结合正常的晶粒生长。该模型也为广泛应用的积雪压实经验模型提供了理论基础。从我们的测量推断的晶格扩散的速率系数是相当高的比公布的值，但是，不能排除其他蠕变机制。
We describe in situ measurements of the compaction of Antarctic snow. At three different sites in Antarctica, the rate of compaction was measured hourly, over various depth intervals, for up to two years. These measurements show that compaction at each of the sites occurs through slow, viscous deformation of the snowpack, with no significant contribution from sudden collapse of weak layers. The measured rates of compaction at the coldest site exhibit a strong seasonality, consistent with a temperature-dependent sintering mechanism having activation energy of 70 kJ mol(-1). At the two warmer sites, activation energies of 80 and 120 kJ mol(-1) provide slightly better agreement with the observations. Published models of snow compaction underestimate the temperature sensitivity. A good match to our observations is provided by a semi-empirical model, based on rate equations for lattice-diffusion (Nabarro-Herring) creep of material around pores, combined with normal grain growth. This model also provides a theoretical basis for a widely used empirical model of snow compaction. The rate coefficient for lattice-diffusion inferred from our measurements is considerably higher than published values, however, and other creep mechanisms cannot be ruled out.