Spatial distribution of surface hoar crystals in sparse forests
Spatial distribution of surface hoar crystals in sparse forests
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稀疏森林地表白晶的空间分布
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
B. Jamieson
中科院分区：
文献类型：
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作者：
C. Shea;B. Jamieson
抽象的。地表积灰的大小和位置直接与雪崩触发点有关，而且它们在小尺度的空间分布中也是如此。从物理上讲，在雪面相对于空气较冷、水蒸气丰富的地方，就会形成表面灰烬。除了水蒸气外，夜间降雪主要是通过长波辐射发射来实现的。发射度可能受到云、树和地形特征的限制。通过96个独立的地表灰白大小的空间点样本，我们展示了树木在402平方米的面积上可以产生的从0到14 mm的极小尺度变化。我们将这种大小变化与树木的影响联系起来，通过使用卫星摄影来估计树木影响每个点的天空景观的量。虽然在物理上与长波逃逸有关，但辐射平衡可能和表面灰烬大小本身一样难以估计。因此，我们仅通过预期的最大面晶尺寸和干燥地形的灰度值来估计点表面灰尘尺寸。我们通过在不同的区域和不同的形成周期中使用它来确认这种关系。在那里，对于表面灰尘尺寸从0到7 mm的区域，其总体平均误差为1.5 mm。
Abstract. Surface hoar size and location relate directly to avalanche initiation trigger points, and they do so in small-scale spatial distributions. Physically, surface hoar will grow where the snow surface is cold relative to the air and water vapour is plentiful. Vapour aside, snow cools at night primarily by longwave radiation emittance. Emittance can be restricted by clouds, trees, and terrain features. With 96 independent spatial point samples of surface hoar size, we show the extreme small-scale size variation that trees can create, ranging from 0 to 14 mm in an area of 402 m2. We relate this size variation to the effects of trees by using satellite photography to estimate the amount that trees impinge on sky view for each point. Though physically related to longwave escape, radiation balance can be as difficult to estimate as surface hoar size itself. Thus, we estimate point surface hoar size by expected maximum areal crystal size and dry terrain greyscale value only. We confirm this relation by using it at a different area and in a different formation cycle. There, its overall average error was 1.5 mm for an area with surface hoar sizes ranging from 0 to 7 mm.