贵州正安夏季雨滴谱特征分析

Analysis of Summer Raindrop Spectrum Characteristics of Zheng’an in Guizhou

为了能更好地对正安夏季降水进行准确预报,需要对本地夏季降水的宏微观特征进行研究,研究2019年夏季6-8月降水持续时间在半小时以上的降水雨滴谱特征,根据降水状况分层积云、对流云及混合云3种情况,分别对粒径分布规律、粒径与降水速度的关系、降水强度与粒径的关系、粒径分布与降水强度贡献率、Z-I关系及降水分布特征几方面进行研究,得出如下结论:(1)3种降水状态,层状云降水粒径变化范围小,速度较低,粒径主要集中在小于1 mm,并且此部分粒子降水贡献率占71.41%;对流云降水粒子变化范围较大,速度可达10 m/s,粒径小于1 mm的粒子占64.4%,但降水贡献率只占16.95%;混合云降水粒子分布介于层状云与对流云之间,由粒径小于1 mm粒径粒子降水贡献率占50%。(2)层状云降水拟合的关系Z=154.86×I1.33,混合云降水拟合的关系Z=172.01×I1.39;对流云降水的Z-I关系Z=498.86×I1.12;3种状态降水拟合关系都比推荐的经典关系数值小。(3)3种状态降水分布特征用GAMMA分布拟合优于M-P分布,用分段拼接拟合,当粒径在0~0.937 mm使用GAMMA分布拟合,粒径大于0.937 mm使用M-P分布拟合的拼接拟合方式对雨滴谱进行拟合更为精确,层状云、对流云以及混合云拟合相关系数分别为99.6%、96.98%、97.16%.

In order to accurately forecast the summer precipitation of Zheng’an,it is necessary to study the macro and micro characteristics of local summer precipitation.In this paper,the characteristics of raindrop spectrum of precipitation lasting more than half an hour from June to August in summer of 2019 are studied.According to the precipitation conditions,there are three kinds of stratocumulus,convective clouds and mixed clouds.The law of particle size distribution,the relationship between particle size and precipitation speed,the relationship between precipitation intensity and particle size,the contribution rate between particle size distribution and precipitation intensity,the relationship between Z-I and the characteristics of precipitation distribution were studied.Get the following conclusions:(1)Among the three precipitation States,the particle size of stratocumulus precipitation has a small change range and a low speed,and the particle size is mainly less than 1 mm,and the contribution rate of this part of particle precipitation accounts for 71.41%.The convective cloud precipitation particles have a wide range of changes,and the speed can reach 10 m/s.The particles with a particle size less than 1 mm account for 64.4%,but the precipitation contribution rate only accounts for 16.95%.The distribution of precipitation particles in mixed cloud is between stratified cloud and convective cloud.the precipitation contribution rate of particles with particle size less than 1 mm accounts for 50%.(2)The relationship between radar reflectivity and precipitation fitted by stratocumulus precipitation is as follows Z=154.86×I1.33.The relationship between radar reflectivity and precipitation fitted by mixed clouds precipitation is as follows Z=498.86×I1.12.The relationship between radar reflectivity and precipitation fitted by convective cloud precipitation is as follows Z=172.01×I1.39.The fitted precipitation relations are all smaller than the recommended classical relations.(3)The distribution characteristics of precipitation in three states are better than M-P distribution by GAMMA distribution fitting.In this paper,piecewise stitching fitting is used that the GAMMA distribution is used to fit when the particle size is in the range of 0-0.937 mm and it is more accurate to fit raindrop spectrum by using M-P distribution fitting when the particle size is larger than 0.937 mm.The fitting correlation coefficients of layered cloud,convective cloud and mixed cloud are 99.6%,96.98%and 97.16%,respectively.