暴雨的发生是多尺度条件和宏微观物理过程相互作用的结果， 对暴雨降水微物理特征的分析是研究暴雨形成机制的重要一环。2021年7月20日15:25 -17:27（北京时， 下同）一强中尺度对流系统影响郑州， 累积降水量312.1 mm， 简称为极端暴雨降水。除极端暴雨降水时段， 20日08:00 -20:00其他时间累积降水量183.4 mm， 简称为暴雨降水。本文利用郑州降水现象仪观测资料， 对比分析了极端暴雨和暴雨降水的雨滴谱和积分参数特征， 主要结论为： （1）暴雨对流降水不同雨强的平均雨滴谱随着雨强增大， 直径D小于1.0 mm的小雨滴数密度增加得较少， 中等（1.0<D≤3.0 mm）和大（D>3.0 mm）直径雨滴数密度增加得较快； 极端暴雨不同雨强平均雨滴谱随着雨强增大， 各直径档雨滴数密度都明显增大， 同时平均雨滴谱粒子数密度之间的差异比较复杂， 有时小雨滴数密度差别大， 有时较大雨滴数密度差别大， 不同雨强平均雨滴谱之间的差异导致参数随着雨强增大的变化特征有显著不同。暴雨参数D _m（lgN _w）随着雨强增大而逐渐增大（稍微增大）， 表明粒子直径的增大是暴雨降水雨强增大的主要因素， 粒子浓度的增加是次要因素。极端暴雨降水参数D _m（lgN _w）随着雨强增大的变化趋势有不同的变化特征， 指示极端暴雨降水不同雨强雨滴谱的形成机制可能存在不同。（2）参数lgN _w-D _m分布显示， 暴雨和极端暴雨对流降水雨滴谱都是以大陆性对流降水为主， 暴雨对流性降水雨滴谱形成机制主要是暖雨-冰相混合和少量冰相控制； 而极端暴雨降水雨强小于100 mm·h^-1时雨滴谱形成机制主要是暖雨-冰相混合和冰相控制， 雨强大于100 mm·h^-1时雨滴谱形成机制主要是暖雨-冰相混合。（3）暴雨降水中存在少量平衡雨滴谱（约占2.8%）和较大比例的过渡谱（约占60.5%）。极端暴雨降水中没有平衡谱， 但过渡谱有极高比例（约占83.9%）， 表明雨滴破碎过程在极端暴雨降水中有更广泛的作用。

The microphysical characteristics is important for the formation mechanism of rainstorm which is the result of multi-scale conditions and the interactions of macro and micro physical processes.From 15:25 （Beijing Time， the same as after） to 17:27 on July 20， 2021， a strong mesoscale convective system affected Zhengzhou， and the accumulated precipitation was 312.1 mm， which was referred to as extreme rainstorm.Excluding the period of extremc rainstorm， from 08:00 to 20:00 on the July 20， the accumulated precipitation was 183.4 mm， which is referred to as rainstorm.Based on the observations data of disdrometer at Zhengzhou station， the characteristics of raindrop size distributions（DSDs） and integral parameters of extreme rainstorm and rainstorm are analyzed.The results showed that： （1）In rainstorm， the average DSDs increased with the increase of rain rate.The concentrations of diameter less than 1 mm increased less， and concentrations of large diameter which is greater than 2 mm increased faster.In extreme rainstorm， the average DSDs increased with the increase of rain rate， and the concentrations of each diameter increased significantly.Meanwhile， the differences between the concentrations of average DSDs at different rain rate were complex.Somewhile there were distinct differences in the concentrations of small raindrops， and there were also great differences in the concentrations of large raindrops.The differences of average DSDs of different rain rate categories lead to different parameters variation with the increase of rain rate.For rainstorm， the D _m increased with the increase of rain rate， while lgN _w increased slightly， indicating that the main source for the increase of rainstorm intensity was the increase of particle diameter， and the secondary factor was increase of particle concentrations.For extreme rainstorm， when the rain rate was between 50 and 100 mm·h^-1， D _m（lgN _w） increased （decreased） with the increase of rain rate， while the rain rate was greater than 100 mm·h^-1， D _m and lgN _w increased slightly with the increase of rain rate， suggesting that the formation mechanisms of DSD in different rain rate categories of extreme rainstorm may be different.（2）The distribution of lgN _w-D _m showed that the DSDs of rainstorm were mainly continental-like， and its formation mechanism was mainly warm-ice mixture process and a small amount of ice-based process.The scatter plot of lgN _w-D _m ofextreme rainstorm with rain rate less than 100 mm·h^-1 mainly clustered on the upper and right side of the continental-like area， and the formation mechanism of extreme rainstorm was mainly warm-ice mixture process and ice-based process； the scatter plot of lgN _w-D _m of extreme rainstorm with rain rategreater than 100 mm·h^-1were mainly distributed on the upperside of the continental -like area， and the formation mechanism was mainly warm-ice mixture process.（3）There were a small proportion（about 2.8%）of the equilibrium raindrop size distribution（EDSD） and a large proportion （about 60.5%）of transition DSDs in rainstorm.There was no EDSD in the extreme rainstorm， while the transition DSDs had a very high proportion （about 83.9%）， indicating that the breakup process played a much more role in the extreme rainstorm.