Nondestructive three-dimensional observations of flow finger and lateral flow development in dry snow using magnetic resonance imaging
Nondestructive three-dimensional observations of flow finger and lateral flow development in dry snow using magnetic resonance imaging
复制标题
使用磁共振成像对干雪中的流指和侧流发展进行无损三维观测
DOI：
10.1016/j.coldregions.2019.102956
复制
发表时间：
2020
影响因子：
4.1
通讯作者：
Kumakura Toshiro
中科院分区：
文献类型：
--
作者：
Katsushima Takafumi;Adachi Satoru;Yamaguchi Satoru;Ozeki Toshihiro;Kumakura Toshiro
由于雪融水或雨水渗入干燥的积雪，形成了流动指。的宽度，间距和面积覆盖的流动指路径和发生的毛细屏障已被证明使用染料示踪剂实验，在现场和冷实验室进行。由于染料示踪剂实验需要对雪进行破坏性分析，因此指进和侧流的初始形状和时间发展尚不清楚。为了检验这一点，我们进行了非破坏性的观察流动手指的发展，并在寒冷的实验室使用磁共振成像（MRI）与三维快速成像方法使用两种不同的干雪样品的毛细管屏障的形成。X射线微计算机断层扫描（μCT）也被用来确定水流现象和雪的微观结构之间的关系。实验结果表明，在干燥的雪样中形成了流动指。流动指状路径的数量增加，并且通过持续的供水发展出侧向流动。孔隙大小和雪密度在垂直方向上的小的不连续性充当毛细屏障并诱导侧向流动。这些结果表明，流动指路径的持久性和流动路径的数量的增加是很重要的理解水渗透到干雪和开发积雪模型，包括水移动过程。使用MRI的非破坏性观察是一种很有前途的技术，以跟踪优先流路和侧流的发展。关于孔隙分布和雪的微观结构在分层积雪的异质性的详细信息是需要了解在自然积雪的水流现象。
Flow fingers develop due to the infiltration of snow meltwater or rain water into a dry snowpack. The width, spacing, and areal coverage of the flow finger path and occurrence of capillary barriers have been demonstrated using dye tracer experiments that were conducted in the field and in cold laboratories. Because dye tracer experiments require the destructive analysis of the snow, the initial shape, and the temporal development of fingering and lateral flows are unclear. To examine this, we carried out nondestructive observations of flow finger development, and the formation of capillary barriers using two different dry snow samples in a cold laboratory using magnetic resonance imaging (MRI) with a three-dimensional rapid imaging method. X-ray micro-computed tomography (μCT) was also used to determine the relationship between the water flow phenomena and the snow microstructure. The experimental results showed that flow fingers developed in dry snow samples. The number of flow finger paths increased, and a lateral flow developed through the continuing water supply. The small discontinuity of the pore size and snow density in the vertical direction acted as a capillary barrier and induced lateral flow. These results showed that both the persistence of the flow finger path and the increase in the number of flow paths are important for understanding the infiltration of water into dry snow and for developing a snowpack model that includes water-moving processes. Nondestructive observation using MRI is a promising technique to follow the development of preferential flow path and lateral flow. Detailed information regarding the heterogeneity of the pore distribution and snow microstructures in a layered snowpack is required to understand the water flow phenomena in a natural snowpack.