庐山地区不同海拔高度降水雨滴谱特征分析

ANALYSIS OF CHARACTERISTICS OF RAINDROP SIZE DISTRIBUTION AT DIFFERENT ALTITUDES IN LUSHAN

利用2010年7月30日架设在庐山的OTT-Parsivel激光雨滴谱仪收集的一次对流云降水雨滴谱资料,对不同海拔高度的降水微物理参量进行比较分析,以探讨降水微物理特征在垂直高度上的差异。结果表明,庐山地区夏季对流性降水,具有时间短、强度大的特点,数浓度、雨强和含水量等微物理参量值普遍较大,雨滴最大直径约为10 mm。降水粒子中所占比例最大的为直径小于1 mm的小雨滴,并且海拔高处的小雨滴所占比例较大。Gamma拟合参数μ和λ的起伏变化趋势基本一致,在确定μ值的情况下,海拔较高处λ值较大,并且用SIFT方法计算的μ—λ关系较为准确。V—D关系符合对数分布,并且直径大于2 mm的雨滴下落末速度偏大于Gunn和Kinzer实验结果,雨滴直径愈大,速度偏大愈明显。相同直径的雨滴,海拔较低处下落末速度较大。

The raindrop size distribution data observed by OTT-Parsivel of a convective rainstorm process in Lushan are used to analyze the characteristics of the microphysical parameters,average raindrop size distributions and raindrop velocity distributions in order to discuss the differences between different altitudes.The results show that for the convective rainstorm in Lushan,the microphysical parameters are larger than those in plain areas,with the 10 mm maximum raindrop size.The particles with diameter less than 1 mm occupy the vast majority,and the proportion increases with the altitude.The Gamma fitting parameters μ and λ present the same trend.For the given μ,λ is larger at higher place,and using SIFT method could obtain more accurate result of μ—λ relationship.The relationship between V—D is in accordance with the logarithm distribution.The fall final speed of raindrop with diameter larger than 2 mm is larger than the result of experimental Gunn-Kinzer curve,the difference increases with the raindrop diameter.For the same diameter,fall final speed at lower place is larger