海南省秋季暴雨过程雨滴谱的特征分析

Characteristics Analysis of Raindrop Size Distribution during Hainan Autumn Rainstorm Process

以2017年海南省海口市秋季暴雨过程为研究对象,利用Parsivel降水粒子谱仪观测到的雨滴谱资料,分析雨滴微物理参量特征及滴谱随降水过程的演变特征.结果显示降水粒子以直径小于1 mm的雨滴为主,直径大于1 mm的雨滴数所占的比例低,但其对雨强的贡献最大.雨滴数浓度、雨强、最大直径和均立方根直径随时间的演变趋势相似,峰值和谷值位置基本一致.降水前期雨滴谱以单峰为主,谱型窄;中期谱型拓宽,滴谱从单峰向双峰甚至三峰演变,有4 mm的大粒子出现;末期谱型变窄,滴谱变回单峰,雨滴数浓度显著降低.当进行Gamma分布的拟合时,直径在1.5 mm^3 mm范围内的雨滴,其拟合最为理想,本研究可为进一步研究热带降水云系的微物理特征提供参考.

In the report,the autumn rainstorm process in Haikou City(Hainan Province)in 2017 was selected as the research object,the raindrop size distribution data obtained by Parsivel precipitation particle spectrometer were used to analyze the microphysical parameters of the raindrop and the evolution characteristics of the droplet size distribution among the precipitation process.The results showed that the precipitation is mainly based on small raindrops with a diameter of less than 1mm;the concentration of raindrops with diameter larger than 1mm is relatively small,however,which has the greatest contribution to rain intensity;the raindrop concentration,rain intensity,maximum diameter and mean cubic root diameter have similar evolution trends with time,and the peak and valley positions are also similar.During the early stage of precipitation,the raindrop size distribution is dominated by single peaks and the spectrum is narrow;during the middle stage of precipitation,the spectrum is broadened,and the droplet size distribution evolves from single peak to double peak or even three peaks,there are 4mm large particles appearing;during the terminal stage of precipitation,the spectrum is narrowed,and the droplet size distribution is changed back to single and the number of raindrops decreased significantly.The fitting of the Gamma distribution showed that the Gamma distribution fits the raindrop spectrum within the diameter range of 1.5mm-3mm,and the correlation analysis between the three parameters of the Gamma distribution and the precipitation intensity,which provides a reference for the further study on the microphysical characteristics of tropical precipitation clouds.