Does wind shear cause hydrometeor size sorting
Does wind shear cause hydrometeor size sorting
复制标题
风切变会导致水凝物大小排序吗
DOI：
10.1175/jas-d-14-0084.1
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发表时间：
2015
影响因子：
3.1
通讯作者：
M. Kumjian
中科院分区：
文献类型：
--
作者：
D. Dawson;E. Mansell;M. Kumjian
摘要最近的几项研究表明，垂直风切变对以其终端速度下落的水凝物的分布产生稳态尺寸分选，该终端速度作为水凝物直径的函数而变化。特别是，这一机制已被调用来解释的强度和风暴的相对方向的通常观察到的差异反射率（ZDR）弧在超级单体雷暴。然而，剪切的实际作用尚未完全阐明。在这项研究中，一个简单的分析模型被用来表明，大小排序的基本来源是风暴相对风场本身，特别是，它的平均值超过深度的排序层。只有在特殊但常见的降水源具有位于速矢线上的运动（例如源水平处的环境风）的情况下，才严格需要风切变来产生持续的尺寸分选。在超级单体中，降水源（旋转的上升气流）不需要...
AbstractSeveral recent studies have implicated vertical wind shear in producing steady-state size sorting of a distribution of hydrometeors falling at their terminal velocity, which varies as a function of hydrometeor diameter. In particular, this mechanism has been invoked to explain both the strength and storm-relative orientation of the commonly observed differential reflectivity (ZDR) arc in supercell thunderstorms. However, the actual role of the shear has not been fully clarified. In this study, a simple analytical model is used to show that the fundamental source of size sorting is the storm-relative wind field itself and, in particular, its mean taken over the depth of the sorting layer. Wind shear is only strictly required for producing sustained size sorting in the special but common case of a precipitation source having a motion that lies on the hodograph (such as with the environmental winds at the source level). In supercells, the precipitation source (the rotating updraft) does not necessari...