GEODAR Data and the Flow Regimes of Snow Avalanches
GEODAR Data and the Flow Regimes of Snow Avalanches
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DOI：
10.1002/2017jf004375
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发表时间：
2018-06-01
影响因子：
3.9
通讯作者：
Sovilla, B.
中科院分区：
文献类型：
--
作者：
Kohler, A.;McElwaine, J. N.;Sovilla, B.
地球物理流动动力学使用脉冲多普勒雷达(GEODAR)，这是一种定制的雷达系统，在瑞士的Vallee de la Sionne实验试验场以高空间和时间分辨率在整个斜坡上拍摄雪崩图像。从2009/2010冬季到2014/2015冬季，共收集了77次雪崩数据。这些数据集描述了各种雪崩，我们根据七种流型及其组合对雪崩进行了分类。这些流动模式在以前分类的基础上进行了扩展，有四种可识别的稠密流动模式(其中颗粒之间的相互作用和与床层的相互作用占主导地位)和两种不同的稀释流动模式(其中雪粒与空气之间的相互作用占主导地位)。还有一种更深入的机制，那就是雪球简单地从山上滚下来。冷密流区和暖切变流区表现为具有速度切变的无粘性颗粒流。当粘聚力占主导地位时，出现滑板区和温塞区，并使流动单元充当在薄剪切带上滑动的类固体物体。间歇性区域连接冷密区域和悬浮区，其特征是密度高度波动和活动激增。GEODAR能够定位这些流型及其在时间和空间上的转变。我们从雪的性质、地形、速度和雪崩的大小等方面讨论了流态的转变。本文还可作为公开提供的数据集的参考，这些数据集应该被证明是基于物理的雪崩模型开发的宝贵资源。
GEOphysical flow dynamics using pulsed Doppler radAR (GEODAR), a custom radar system, images avalanches over the entire slope with high spatial and temporal resolution at the experimental test site Vallee de la Sionne in Switzerland. Between winter seasons 2009/2010 and 2014/2015, data have been acquired from 77 avalanches. These data sets describe a wide variety of avalanches, which we classify in terms of seven flow regimes and combinations thereof. These flow regimes expand on previous classifications, with four identifiable dense flow regimes (where interaction between granules and with the flow bed dominates dynamics) and two different dilute flow regimes (where interaction between snow particles and the air becomes dominant). There is a further regime identified where snow balls simply roll down the mountain. A cold dense regime and a warm shear regime behave like noncohesive granular flows with velocity shear throughout the flow. A sliding slab regime and a warm plug regime occur when cohesion dominates and causes the flow units to act as solid-like objects sliding on a thin shear zone. An intermittent regime connects the cold dense regime with the suspension regime and is characterized by highly fluctuating density and surging activity. GEODAR enables localization of these flow regimes and transitions between them in time and space. We discuss flow regime transitions in terms of snow properties, topography, speed, and size of the avalanches. This paper also serves as a reference for the data set which is made publicly available and should prove to be an invaluable resource for the development of physically based avalanche models.