声波干预下微液滴群微物理变化及其与雷达反射率因子关系研究

Microphysical changes of droplets and their relationship with radar reflectivity factor under acoustic interference

通过室内实验,探究了声波干预下微液滴群微物理变化特征,建立了滴群特征粒径与雷达反射率因子之间的关系,讨论了粒径增量与宏观雨强增量之间的量化关系。结果表明:(1)存在优选声波频率和临界声压级,实验重点关注的120 Hz声波频率(超过临界声压级)干预实验滴群,引起微液滴群特征粒径增大、粒径谱右移变宽,粒子数浓度减小,雷达反射率因子增大,该结论对于30~280 Hz声波同样适用。(2)D90-Z相关系数在0.9以上,大粒径对雷达反射率因子贡献较大,拟合参数a、b范围分别为[2.84×10^(-8),1.104]和[0.6713,9.2000]。(3)滴群特征粒径增量与宏观雨强增量呈线性正相关关系,相关系数均在0.98以上,并且声压级越大,拟合的线性斜率越小。研究结果对外场试验效果评价具有重要的参考意义和指导价值。

Through laboratory experiments,the characteristics of microphysical changes of microdroplet clusters under acoustic wave intervention were explored,the relationship between the characteristic particle size of droplet clusters and the radar reflectivity factor was established,and the quantitative relationship between the increment of particle size and the macroscopic rain intensity increment was discussed.The results reveal the following:(1)Optimal acoustic frequencies and critical sound pressure levels are observed.The experiments focused on clusters of drops with 120 Hz acoustic frequencies and exceeding the critical sound pressure level.The acoustic intervention causes the characteristic particle size of the microdroplets to increase,the right shift of the particle size spectrum to widen,the particle number concentration to decrease,and the radar reflectivity factor to increase.This conclusion is also applicable to the 30-280 Hz acoustic wave range.(2)The correlation coefficient of D90-Z is above 0.9,indicating that large particle sizes considerably contribute to the radar reflectivity factor.The fitting parameters a and b are in the ranges of[2.84×10^(−8),1.104]and[0.6713,9.2000],respectively.(3)The characteristic particle size increment of the droplets is linearly positively correlated with the macroscopic rain intensity increment,with correlation coefficients all above 0.98.In addition,as the sound pressure level increases,the linear slope of the fitting decreases.This study provides a substantial reference and guiding value for evaluating field test effects.