VARIABILITY OF THE SUPERSATURATION IN CUMULUS CLOUDS
VARIABILITY OF THE SUPERSATURATION IN CUMULUS CLOUDS
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DOI：
10.1175/1520-0469(1988)045
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发表时间：
1988-06-01
影响因子：
3.1
通讯作者：
COOPER, WA
中科院分区：
文献类型：
--
作者：
POLITOVICH, MK;COOPER, WA
通过对垂直风、云滴大小、温度和压力的测量，计算了1981年合作对流降水实验中积云的准稳态过饱和度。给出了过饱和度的均值和光谱特征。147个云区的过饱和度平均值接近0%，（10 m平均值）过饱和度值的标准差从未混合区域的0.1%到被夹带稀释约80%的区域的0.4%左右。确定了垂直风、积分半径和过饱和度的欧拉方差谱，并描述了一种估计拉格朗日谱的技术。据估计，混合区域过饱和的拉格朗日特征时间约为50秒，而在一些上升气流强的区域则要大得多。有人认为，观察到的过饱和变率与考虑液滴尺寸谱中的典型色散所需的变率相当。
The quasi-steady supersaturation in cumulus clouds from the Cooperative Convective Precipitation Experiment of 1981 are calculated from measurements of vertical wind, cloud droplet size, temperature and pressure. Mean values and spectral characteristics of the supersaturation are presented. The supersaturation values in 147 cloud regions averaged near 0%, with standard deviations in the (10-m average) supersaturation values that ranged from 0.1% in unmixed regions to about 0.4% in regions about 80% diluted by entrainment. The Eulerian variance spectra for vertical wind, integral radius and supersaturation were determined, and a technique is described for estimating the Lagrangian spectra. The Lagrangian characteristic times for supersaturation were estimated to be about 50 s for mixed regions but substantially larger for some regions with strong updrafts. It is argued that the observed variability in supersaturation is comparable to that needed to account for typical dispersions in droplet size spectra.