中国大范围雷暴大风事件（Derechos）研究:时空分布、环境背景和对流系统形态特征

基于2002—2019年高空、地面常规观测资料，卫星云图，部分新一代天气雷达单站资料以及2009年以后的中国雷达拼图资料，采用个例筛选与统计、动态合成分析、层次聚类和雷达图分析等方法，对发生在中国的大范围雷暴大风事件（Derechos）的时空分布、环境背景和对流系统形态特征进行了分析。结果表明:（1）Derechos事件主要发生在华北、华东、江南和华南地区，高频区有明显的季节变化，春季到夏季先向北移动后向南移动；Derechos事件主要发生在3—8月，6月频率最高，8月最低；造成Derechos的对流风暴多在正午前后生成，而Derechos事件多开始于午后到前半夜。（2）中国Derechos事件环境参数主要特征为:对流有效位能（CAPE）分布50%分位（中位数）为1420 J/kg，代表深层风垂直切变的0—6 km风矢量差50%分位数为18.0 m/s，对流下沉有效位能（DCAPE）的50%分位值为1090 J/kg。（3）Derechos事件环流背景的天气流型配置分为副高边缘型、弱槽型、高空干冷平流强迫型和强槽型，强槽型出现的频次最高，高空干冷平流强迫型出现的频次最低。（4）Derechos事件中最强对流大风产生时段的对流系统形态统计显示，出现频率由高到低分别为飑线、多单体风暴簇、超级单体或超级单体复合体。 

Investigation of Derechos in China:Spatiotemporal distribution,environmental characteristics,and morphology of Derechos producing convective systems

Based on the 36 Derechos that occurred in China during 18 years from 2002 to 2019,a study on the spatiotemporal distribution and environmental characteristics of Derechos as well as the morphology of Derechos producing convective systems have been conducted using proximity soundings,surface observations,satellite images,single Doppler weather radar data,and weather radar mosaics data.The results are as follows.(1)Derechos mainly occur in the eastern half of China,including North China,East China,South China,and regions to the south of the Yangtze River.The regions of high occurrence frequency show remarkable seasonal variation,which is manifested as the northward movement during the first phase and the southward movement during the second phase from spring to summer.Derechos activity has significant seasonal changes.They mainly occur from March to August with the highest frequency in June and the lowest in August.The convective systems producing the Derechos tend to initiate around noon,while the Derechos themselves tend to occur between mid-afternoon and early midnight.(2)The main characteristics of environmental parameters of Derechos in China are as follows:The 50 th percentile of CAPE is 1420 J/kg,the 50 th percentile of the0-6 km vertical shear is 18.0 m/s,the 50 th percentile of DCAPE is 1090 J/kg.(3)The weather pattern of Derechos can be divided into the following four types:The subtropical high periphery type,the weak trough type,the high level dry-cold advection forced type and the strong trough type,among which the strong trough type has the highest frequency and the high level dry-cold advection forced type has the lowest frequency.(4)During the period when the maximum wind gust occurs,the most frequent convective storm type is squall line,the second frequent storm type is multi-cell cluster storm and the third frequent storm type is supercell storm.