遵义地区一次暴雨雨滴谱特征及在雷达中的应用

Raindrop Size Distribution Characteristics of a Rainstorm in Zunyi Area and its Application in Radar

根据遵义地区的OTT Parsivel雨滴谱仪观测的一次暴雨雨滴谱资料、天气雷达观测资料以及自动站降水资料,对暴雨过程中的雨滴谱参数和雨滴谱分布特征进行分析,发现中粒径雨滴贡献率最大;质量加权平均直径和粒子数密度成负相关;在对平均雨滴谱拟合时发现,Gamma分布在中粒径拟合效果比M-P分布好,而在大粒径和小粒径符合程度效果相差不大;比较雷达回波强度与雨滴谱特征参量的雷达反射率之间的关系,通过取3次平均来修正雷达回波强度,结果表明:修正后的数据和雨滴谱雷达反射率因子的相关系数高达99.59%,且均方误差和平均绝对误差都很小;再构建修正后的天气雷达反射率因子与雨滴谱计算的雨强的Z-I关系,得到拟合的Z-I关系曲线Z=133.98I^(1.12)利用拟合的Z-I关系计算的雨强与用雨滴谱数据计算的雨强相关系数达到99.53%。因此,通过雨滴谱参数修正后的雷达回波反射率可以准确估测降水。

According to the raindrop size distribution data of a rainstorm observed by OTT Parsivel Laser Weather Sensor,weather radar observation data and automatic station precipitation data in Zunyi,the raindrop size distribution parameters and distribution characteristics of raindrop size distribution in the process of rainstorm was analyzed,which could found that the contribution rate of medium-size raindrops is the largest.Meanwhile,the mass weighted average diameter is negatively correlated with the particle number density.Moreover,the Gamma distribution has a better fitting effect than the M-P distribution for the medium particle size when fitting the average raindrop size distribution,while the fitting effect for the large and small particle size is similar.By comparing the relationship between the radar echo intensity and the radar reflectance of the characteristic parameters of the raindrop size distribution,the radar echo intensity is corrected by taking the average of three times,the results showed:the correlation coefficient between the corrected data and the radar reflectance factor of the raindrop size distribution is as high as 99.59%,and the mean square error and mean absolute error are small.Then the Z-I relationship between the corrected weather radar reflectivity factor and the rainfall intensity calculated by the raindrop size distribution was constructed,and the fitted Z-I relationship curve(Z=133.98 I^(1.12))was obtained.The accuracy of the rain intensity obtained by the weather radar reflectivity factor and the rain intensity calculated by the raindrop size distribution reached 99.53%,by using the fitted Z-I relationship.Overall,using radar echo reflectance modified by raindrop size distribution parameters could estimated more accurately.