Geometric Versus Anemometric Surface Roughness for a Shallow Accumulating Snowpack
Geometric Versus Anemometric Surface Roughness for a Shallow Accumulating Snowpack
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浅积雪的几何表面粗糙度与风速表面粗糙度
DOI：
10.3390/geosciences8120463
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发表时间：
2018
期刊：
影响因子：
2.7
通讯作者：
I. Oprea
中科院分区：
文献类型：
--
作者：
J. Sanow;S. Fassnacht;D. Kamin;G. Sexstone;W. Bauerle;I. Oprea
当应用于积雪表面时，空气动力学粗糙度长度 z0 通常被视为能量平衡方程中的静态参数。然而，现场观察表明，z0 在空间和时间上发生变化，因此将 z0 作为动态参数可以极大地改进模型。为了评估表征雪表面粗糙度的方法，我们比较了基于（1）地面光检测和测距导出的积雪表面表面几何形状（几何，z0G）和（2）垂直风廓线测量（风速测量，z0A）的 z0 的同时估计。 z0G 的值是根据 Lettau 方程计算的，低估了 z0A，但在按 2.34 倍缩放时比较良好。人们发现计算 z0G 的 Counihan 方法不适合估计雪面上的 z0。在初冬积雪期间，z0 作为积雪面积 (SCA) 的函数而变化。我们的结果表明，随着 SCA 的增加，z0 减小，表明地形对这种关系有影响。
When applied to a snow-covered surface, aerodynamic roughness length, z0, is typically considered as a static parameter within energy balance equations. However, field observations show that z0 changes spatially and temporally, and thus z0 incorporated as a dynamic parameter may greatly improve models. To evaluate methods for characterizing snow surface roughness, we compared concurrent estimates of z0 based on (1) terrestrial light detection and ranging derived surface geometry of the snowpack surface (geometric, z0G) and (2) vertical wind profile measurements (anemometric, z0A). The value of z0G was computed from Lettau’s equation and underestimated z0A but compared well when scaled by a factor of 2.34. The Counihan method for computing z0G was found to be unsuitable for estimating z0 on a snow surface. During snowpack accumulation in early winter, z0 varied as a function of the snow-covered area (SCA). Our results show that as the SCA increases, z0 decreases, indicating there is a topographic influence on this relation.