Interfacial and structural relaxations of snow under isothermal conditions
Interfacial and structural relaxations of snow under isothermal conditions
复制标题
等温条件下雪的界面和结构松弛
DOI：
10.3189/002214311796905569
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发表时间：
2011
影响因子：
3.4
通讯作者：
M. Schneebeli
中科院分区：
文献类型：
--
作者：
H. Löwe;J. K. Spiegel;M. Schneebeli
摘要我们使用X射线断层扫描技术研究了实验室雪在−3 ° C、−9 °C和−19°C等温条件下的形态演变。我们采用两点密度相关函数测量了不同尺度下双连续冰/水汽系统密度的空间涨落。长度尺度来自相关函数，以区分由于最小尺度上的表面能最小化而导致的界面粗化和由于较大尺度上的重力而导致的各向异性结构重排。在最小尺度上，我们的数据表明，T = −9和−19°C之间从蒸发/冷凝到表面扩散的交叉是主要的传输机制。发现在原点的相关函数的斜率的异常增长，这是类似于那些报道的分形集团的粗化。这与观察到的树枝状结构持续一整年是一致的。大尺度形态的动力学的特征在于由第一个零交叉的相关函数，它显示了一个非单调的演化与重力方向和水平方向之间的显着的各向异性。由于相关函数自然出现在雪中的辐射散射的问题，我们的结果似乎是重要的光学和遥感方法。
Abstract We investigated the morphological evolution of laboratory snow under isothermal conditions at −3,−9 and −19°C, using X-ray tomography. We employed a two-point density correlation function to measure spatial fluctuations of the density of the bicontinuous ice/vapor system at different length scales. Length scales were derived from the correlation function to distinguish between interfacial coarsening due to the minimization of surface energy on the smallest scales and anisotropic structural rearrangements due to gravity on larger scales. On the smallest scales our data suggest a crossover between T = −9 and −19°C from evaporation/condensation to surface diffusion as the dominant transport mechanism. Anomalous growth was found for the slope of the correlation function at the origin, and it was similar to those reported for the coarsening of fractal clusters. This is consistent with the observed persistence of dendritic structures throughout an entire year. The dynamics of large-scale morphology was characterized by the first zero-crossing of the correlation function which displays a nonmonotonic evolution with a pronounced anisotropy between the direction of gravity and horizontal directions. Since the correlation function naturally emerges in problems of scattering of radiation in snow, our results appear to be important for optical and remote-sensing methods.