山东不同云系降水微物理参数特征

Characteristics of Rain Microphysical Parameters for Different Cloud Systems in Shandong Province

研究不同云系降水的微物理参数特征,对研究降水机制、人工影响天气、雷达定量测量降水、数值预报模式中微物理参数化方案的选择等都有一定意义。本文针对2015年济南地区的液态降水过程,基于微降水雷达(Micro Rain Radar,简称MRR)资料,研究不同云系降水的微物理参数。在400 m高度上,层状云降水0.02~0.2 mm h-1雨强样本数很大,但对累计降水量的贡献很小。混合云和对流云降水在大粒子端数浓度较高。在垂直方向上,层状云降水中的粒子的尺度较集中,中值体积直径D0平均在1 mm左右,随高度的变化不大。对流云降水在雨强大于20 mm h-1时,强垂直气流(包括上升气流和下沉气流)对粒子直径的影响较大,进而影响空中微降水雷达反演降水参数的数据质量。而垂直气流的影响对层状云降水影响较小,在层状云降水时,微降水雷达可以用来分析零度层亮带以下雨滴谱在垂直方向上的演变。

Investigating the microphysical parameter characteristics of precipitation in different cloud systems is of considerable significance to study the precipitation mechanism,weather modification,radar quantitative measurement of precipitation,and selection of the microphysical parameterization schemes using numerical prediction models.Further,the microphysical parameters of precipitation in different cloud systems were studied and evaluated on the basis of the micro rain radar(MRR)data in accordance with the liquid precipitation process that occurred in Jinan,Shandong Province,in 2015.The rainfall intensity samples of the stratiform precipitation were quite large at 0.02–0.2 mm h-1 at an altitude of 400 m;however,their contribution to the cumulative precipitation remained relatively small.The number concentration of large particles was high in convective and mixed precipitation.The particle diameter in case of stratiform precipitation was relatively concentrated in the vertical profile,and the average D0 was observed to be approximately 1 mm below an altitude of 1,400 m.Further,the vertical airflow(including the updraft and downdraft)considerably impacted the particle diameter when the rainfall intensity of the convective precipitation became greater than 20 mm h-1;the data quality of the precipitation parameters retrieved by MRR was relatively poor,especially at upper range gates.Meanwhile,the MRR data can be used to analyze the vertical evolution of the raindrop spectrum below the bright band during stratiform precipitation,which is minimally impacted by the vertical airflow.