广东地区一次飑线过程的地面雨滴谱特征分析

CHARACTERISTICS OF THE RAINDROP SIZE DISTRIBUTION IN A SQUALL LINE MEASURED BY TWO-DIMENSIONAL VIDEO DISDROMETER IN GUANGDONG

利用3台二维视频雨滴谱仪(2DVD)、广州S波段双偏振雷达以及C-FMCW雷达资料,分析广东地区2017年5月8日一次飑线过程不同降水部位的雨滴谱特征。根据雨强随时间变化,区分对流降水区,同时以对流降水区为分界线,将此次飑线过程划分为飑线前部、飑线中部和飑线后部。结果表明,飑线不同降水部位雨滴谱特征存在明显的差别。飑线前部,粒子谱分布变化剧烈,中小粒径的粒子居多,粒子数浓度较飑线中部偏低;飑线中部,粒子分布较分散,中等粒子比重较高,粒子数浓度最高,雨强的增加主要与雨滴数浓度有关;飑线后部,降水粒子分布较集中,且以高浓度中小粒子为主。另外,还研究了μ-Λ关系和Z-R关系。μ-Λ之间存在较好的二项式关系;不同降水部位Z-R关系差异较大,分别为Z=8.94R2.70、Z=526.98R1.22和Z=467.56R1.42。飑线不同部位雨滴谱演变特征存在一些明显差别,同时,同一部位不同空间位置也存在着一定的差异。

Temporal evolution and spatial variations of the characteristics of raindrop size distribution(DSD)in a squall line in Guangdong on May 8,2017 are analyzed using data from three two-dimensional video disdrometers(2DVD)at Longmen Field Experiment Base on Cloud Physics,China Meteorological Administration,Guangzhou S-band Polarimetric Weather Radar and C-band Frequency Modulation Continuous Wave(C-FMCW)from Chinese Academy of Meteorological Sciences.This squall line is divided into leading edge,convective subject and trailing edge based on radar reflectivity and rain rate.Results show that,compared with the DSDs in the convective subject,the DSDs in the leading edge are characterized by a higher concentration of midsize and small drops,and a lower drop number concentration;in the convective subject,the concentration of raindrop within each size range is the highest,and the enhanced changes of rainfall are related to the raindrop number concentration;in the trailing edge,the DSDs are characterized by narrower and smoother spectra,and a higher concentration of midsize and small drops.Statistical characteristics of the Z-R andμ-Λrelationship are studied.The Z-R relationship of leading edge,convective subject and trailing edge is Z=8.94R2.70,Z=526.98R1.22 and Z=467.56R1.42,respectively.DSDs in different parts of a squall line have some obvious differences,while imparity can also be found in different spatial position within the same part of a squall line.