两个中尺度对流系统的降水结构和闪电特征

对两个处于不同发展阶段的中尺度对流系统(MCS)降水结构的分析结果表明,处于初生至发展阶段的MCS,对流降水和层云降水的面积比相对较大,处于成熟至消亡阶段的MCS的相对较小。本文进一步分析了这两个MCS个例在6km高度处的雷达回波特征及其和闪电的关系,结果表明处于初生至发展阶段的MCS的绝大部分事件(闪电资料的一种)集中发生在MCS中的强对流单体回波区,而对处于成熟至消亡阶段的MCS,事件集中发生在对流区和对流云向层云转化的回波区。

ANALYSIS OF THE STRUCTURES OF RAINFALL AND THE CHARACTERS OF LIGHTNING OF TWO MESO SCALE SYSTEMS

Two samples of mesoscale convective system (MCS) were selected for study, the structure of the rainfall and the characters of radar reflectivity at 6 km altitude were analyzed. The relationship between the characters of the radar reflectivity at 6 km altitude and the lightning characters was given. In the MCS at the new born to developing stage, the ratio of the area of the convective rain to the stratiform rain is larger than that of the MCS at the mature to dissipative stage. The ratio is only 0.15 of the MCS2, indicating large area of the stratiform rain. Three-dimensional rainfall structures of the two samples of the MCSs indicated that the shapes of the radar reflectivity of the convective rain were looked like columns, and that the altitude of the radar reflectivity height of the convective rain was obviously higher than that of the stratiform rain. It was always more than 10 km high. The radar reflectivity of the stratiform rain was relatively lower and broader. Generally, it was not higher than 6 km. Furthermore, the relation between the radar reflectivity and the characters of lightning was discussed. The result showed that most events (one kind of lightning data) occurred between 20 and 45 dBz, which corresponded to the area of the convective rain and part of the stratiform rain. Distribution of the events was different in developing stages of MCS. In the MCS at the new born to developing stage, the number of the events was relatively small. Most events occurred between 25 and 45 dBz, corresponding to the area of the convective monocase in the MCS. In the MCS at the mature to dissipative stage, the number of the events was relatively large. Most events occurred between 20 and 45dBz, corresponding to the area of the convective rain and the transition area of the convective cloud to the stratiform cloud in the MCS.