山东一次适宜增雨作业的雨滴谱特征分析

Analysis on Raindrop Spectral Characteristics of a Feasible Artificial Precipitation in Shandong Province

为了解降水微物理特征,更好地为增雨抗旱气象服务提供技术支持,本文以2015年4月18~19日发生在山东的一次适宜人工增雨作业的降水过程为例,利用激光雨滴谱仪获取的观测资料对雨滴微物理参量的连续演变特征、雨滴谱微物理参量特征以及降水不同阶段雨滴谱特征等方面进行分析。结果表明,降水强度决定于雨滴谱谱宽和雨滴数浓度,三者随时间变化趋势大致相同,峰区和谷区出现的位置基本一致;各谱特征参量与降水强度间均呈正相关性,即都随雨强的增大而增大;在雨强基本小于1 mm/h的降水第一阶段,谱宽仅为1.75 mm,而进入到雨强多数大于1 mm/h的降水第二阶段时,谱宽为3.5 mm;对于雨滴数浓度而言,降水第二阶段各档粒径数浓度远大于降水第一阶段中各粒径档数浓度值,仅粒径在0.375~0.5 mm之间时,降水两个阶段的雨滴数浓度值基本相同,在102量级。

To understand the micro-physical properties of precipitation and well to provide a certain technical supports for precipitation and drought weather service, raindrop size spectra were collected with an optical disdrometer during the precipitation for fitting artificial precipitation enhancement in April 18~19 2015 in Shandong Province. The characteristics of the micro-physical parameters varied with the time, the relations of micro-physical parameters with precipitation intensity and the average raindrop size distributions for different stages of the precipitation were investigated. It was found that the precipitation intensity was decided by the maximum diameter and number concentration, the three trends over time were roughly same and the location of the peak and valley area appeared almost the same. The micro-physical parameters and precipitation intensity had positive linear correlations, in other words, they increased with the increase of rainfall intensity. In the first stage that the rainfall intensity was basically less than 1 mm/h, the distribution of raindrop size was very narrow and the width was only 1.75 mm. But in the second stage that the rainfall intensity was mainly more than 1 mm/h, the distribution of raindrop size was apparently broadened and the width was attained to 3.5 mm. In the second stage of the precipitation, the number of raindrops concentration was greater than that in the first stage and while the raindrop diameters were between0.375 and 0.5 mm, the number of raindrops concentration was basically the same with 102 orders of magnitude.