Back analysis of drifting-snow measurements over an instrumented mountainous site
Back analysis of drifting-snow measurements over an instrumented mountainous site
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仪器化山区流雪测量的反分析
DOI：
10.3189/172756410791386661
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发表时间：
2010
影响因子：
2.9
通讯作者：
M. Naaim
中科院分区：
文献类型：
--
作者：
F. Naaim;H. Bellot;M. Naaim
本文介绍了NEMO积雪数值模式的基本概况，该模式是建立在跃移和湍流扩散物理模型基础上的。该模型需要一组输入参数，包括降落速度，临界剪切速度，剪切速度，质量浓度和粗糙度，这是从经验公式和风速测量在给定的高度。为了更好地确定高山环境中所需的野外数据，我们的实验地点，Col du Lac Blanc（2700ma.s.l.），法国阿尔卑斯山的一个小型风力发电站首次配备了一个风速计和吹雪声传感器，尽管使用了新的校准曲线，但在目前的发展状况下，这一传感器被证明不足以用于研究目的。因此，我们设置了一个雪粒子计数器，并回到了传统的，强大的机械陷阱和一个10米的桅杆，六个风速计，两个温度传感器和一个深度传感器，以更好地确定摩擦速度和空气动力学粗糙度。通过对几种典型的积雪事件的研究，得出以下结论：（1）空气动力学粗糙度与摩擦速度的平方成正比，但比例系数随积雪事件的不同而变化;（2）南极资料的经验公式较好地近似了σsUF值，（3）Pomeroy的跃移层半经验公式结合扩散层理论方法得到的雪堆浓度廓线高估了所研究的吹雪事件的浓度廓线。
Abstract The NEMO numerical model of drifting snow, whose general outlines are presented in this paper, is based on a physical model for saltation and turbulent diffusion. The model needs a set of input parameters including fall velocity, threshold shear velocity, shear velocity, mass concentration and roughness, which are obtained from empirical formulae and wind speed measured at a given height. To better determine the required field data in an alpine context, our experimental site, Col du Lac Blanc (2700ma.s.l.), French Alps, was first equipped with one anemometer and blowing-snow acoustic sensors, which proved not to be accurate enough for research purposes in the current state of development even though a new calibration curve was used. We therefore set up a Snow Particle Counter and we returned to the traditional, robust mechanical traps and a 10 m mast with six anemometers, two temperature sensors and a depth sensor to better determine friction velocity and aerodynamic roughness. Based on the studied drifting-snow events we conclude: (1) the proportionality of the aerodynamic roughness to the square of the friction velocity was confirmed, but with a varying proportionality ratio depending on the snowdrift event; (2) values of σsUF were relatively well approximated by empirical formulae from data originating from Antarctica, and (3) snowdrift concentration profiles obtained by Pomeroy’s semi-empirical formulae for the saltation layer coupled with a theoretical approach for the diffusion layer overestimated the concentration profiles for the studied blowing-snow event.