强台风“妮妲”降水过程惠州雨滴谱特征分析

Analysis of the Characteristics of Raindrop Spectra of the Precipitation in Huizhou with the Visit of Severe Typhoon Nida

利用惠州市惠阳观测站雨滴谱数据,分析了强台风“妮妲”过程期间台风降水的雨滴谱特征。强台风“妮妲”过程期间最大雨滴浓度为28662 m^(-3),最大瞬时降雨强度为96 mm/h,以小雨滴居多,直径小于1 mm的雨滴占总浓度的91.08%,平均雨滴直径D_(m)在0.5mm左右,众数直径D_(d)最多为0.437 mm,平均体积直径D_(v)的平均值为0.723 mm,优势直径中最多的为1.375 mm的雨滴,中数体积直径集中在1.062~1.375 mm之间,强台风“妮妲”惠州的降水以非对流性降水为主。随着强台风“妮妲”登陆靠近,大小雨滴的浓度均急剧增加,出现少量大于6.5 mm的大滴,接近台风中心后呈下降趋势,随后又增加并保持较高浓度小雨滴。应用指数分布和Г分布模型对雨滴谱进行拟合,结果表明指数分布拟合效果略优。

Using the data of raindrop spectra from observation stations in Huiyang,Huizhou,this work analyzes the characteristics of raindrop spectra during the visit of severe typhoon Nida.The results are shown as follows.During Nida’s visit,the maximum raindrop concentration is 28662/m^(3) and maximum transient rain rate is 96 mm/h,with fine raindrops(with the diameter less than 1 mm)taking up 91.08% of the total concentration.The average raindrop diameter(D_(m))is around 0.5 mm,the mode diameter(D_(d))is 0.437 mm(with the most appearances),and the mean value of average volume diameter(D_(v))is 0.723 mm.The raindrop with the most concentration to water content has the leading dominant diameter(1.375 mm)and the diameter of the median volume concentrates in the range from 1.062 to 1.375 mm.In Huizhou,the precipitation with Nida is mostly non-convective.With the landfall of the severe typhoon,the concentration of raindrops in all diameters increases rapidly,with a number of large raindrops with the diameter larger than 6.5 mm.The trend turns to decrease with the approach of the typhoon eye before increasing again and fine raindrops in high concentration stay for some time.As shown in a fitting of raindrop spectra using models of index distribution and Г distribution,the former has a slightly better fitting result.