Raindrop sorting induced by vertical drafts in convective clouds
Raindrop sorting induced by vertical drafts in convective clouds
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对流云中垂直气流引起的雨滴排序
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
F. Marks
中科院分区：
文献类型：
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作者：
P. Kollias;B. Albrecht;F. Marks
对流上升气流引起的雨滴分选的证据。使用垂直指向的94 GHz多普勒雷达（λ=3.2 mm），并利用后向散射截面的共振性质作为雨滴大小的函数（米氏散射），从多普勒频谱中反演出精度为0.1 ms−1的垂直空气运动和雨滴大小分布的形状。垂直气流和雨滴的相互作用首次被高分辨率雷达数据记录下来。上升气流结构明显地导致雨滴的水平和垂直分选。在上升气流核心中，观测到终端速度小于上升气流速度（6-7 ms−1）的小雨滴（D ≤ 1.7 mm），并且明显没有大于3 mm的雨滴。在上升气流的外围，雨滴的大小逐渐增加，在那里观察到大雨滴（D ≥ 3 mm）。观测结果表明，上升气流在空间分布雨滴的重要性。
Evidence of raindrop sorting induced by a convective updraft is presented. Using a vertically pointing 94‐GHz Doppler radar (λ=3.2 mm) and capitalizing on the resonant nature of the backscattering cross‐section as a function of the raindrop size (Mie scattering), the vertical air motions to an accuracy of 0.1 ms−1, and the shape of the raindrop size distribution are retrieved from the Doppler spectra. The interaction of vertical drafts and raindrops is documented for the first time by high resolution radar data. The updraft structure clearly causes horizontal and vertical sorting of the raindrops. In the updraft core, small raindrops (D ≤ 1.7 mm) that have terminal velocities less than the updraft velocities (6–7 ms−1) and a clear absence of drops ≥3 mm are observed. Towards the updraft periphery, a gradual increase in the raindrop sizes is documented where large raindrops (D ≥ 3 mm) are observed. The observations demonstrate the importance of updrafts in distributing the raindrops in space.