春季粤北地区降水微物理特征分析

Analysis of the Microphysical Characteristics of Springtime Precipitation in Northern Guangdong Province

为揭示春季粤北降水微物理过程,选取2020年2—3月粤北2个站点雨滴谱仪观测资料,统计分析了春季粤北地区层云降水、混合性降水、对流性降水的微物理特征,结果表明:(1)对流性降水过程中大雨滴是影响雨强大小的重要因素;层云降水过程,小雨滴数浓度占比大于90%,平均雨强小于1 mm/h,雨滴数是影响雨强的重要因素。(2)层云性降水雨滴谱呈单峰结构,谱宽小;对流性降水雨滴谱为多峰结构,谱宽最大;混合性降水谱型与对流性降水相似。3类降水峰值均在0.2~0.3 mm范围,均是Gamma分布谱型拟合最优。(3)春季粤北地区对流性降水的Z-I关系为Z=173.9I^(1.452),混合性降水的Z-I关系为Z=72.77I^(1.97),层云性降水过程的Z-I关系为Z=194.3I^(1.296)。

To reveal the microphysical processes of springtime precipitation in northern Guangdong,the observational spectra for February and March 2020 from two sites in this part of the province are used to perform a statistical study of stratus precipitation,mixed precipitation and convective precipitation.The results are shown as follows.(1)Large raindrops for convective precipitation are an essential factor in determining the rainrate.For stratus precipitation,fine raindrops take up more than 90% of the number concentration and the average rainrate is smaller than 1 mm/h.The number of raindrops is an important factor governing the rainrate.(2)For the stratus precipitation,the raindrop size distribution(DSD)is unimodal with small spectral width.For the convective precipitation,it is mostly multimodal with the spectral width being the largest among the three types of precipitation.The DSD of the mixed precipitation is similar to that of the convective precipitation.For the three types of precipitation,the peaks are all within the range of 0.2 to 0.3 mm and the raindrop distributions all best conform to the DSD of Gamma distribution.(3)In spring in northern Guangdong province,the Z-I relationship is Z=173.9I^(1.452) for the convective precipitation,Z=72.77I^(1.97) for the mixed precipitation,and Z=194.3I^(1.296) for the stratus precipitation.