高级搜索

2022年广西雷暴活动特征分析

Statistic analysis of thunderstorm characteristics in Guangxi in 2022

  • 摘要: 基于2022年广西三维闪电监测资料、雷达三维拼图数据,融合利用风暴识别追踪技术(Storm Cell Identification and Tracking,SCIT)和DBSCAN (Density-Based Spatial Clustering of Applications with Noise)算法,识别提取1 131个雷暴单体构建雷暴特征数据集,并基于该数据集研究广西雷暴单体的时空分布、移动方向、持续时间、移动速度、移动距离等特征,并进一步对雷暴发生环境下雷达基本反射率、垂直积分液态水含量(VIL)、回波顶高等分布特征进行统计分析。结果表明:(1) 广西雷暴呈南多北少的特征,南部沿海地区的雷暴活动最强;夏季(6—8月)雷暴高发,占全年雷暴数的65.3%,冬季(12—2月)雷暴占比仅为0.18%。一天之中雷暴活动主要发生在11—19时。(2) 雷暴单体的移动速度集中在2~16 m·s-1,以4~6 m·s-1为最多;移动距离集中在100 km以内,以10~20 km为最多;移动方向以东北向、北向、西北向和东向为主。不同移动方向的雷暴单体移动距离、速度均存在一定差异,其中朝东方向移动的雷暴单体速度偏快(8~16 m·s-1),移动距离较远(10~40 km);朝南方向移动的雷暴单体速度总体偏慢(2~10 m·s-1),移动距离较短(0~30 km);其他移动方向的雷暴单体速度集中在4~12m·s-1,但峰值区间略有差异。(3) 雷暴内初闪常发生于雷达反射率大于45 dBz且VIL小于30 kg·m-2的区域中,初闪之后的闪电主要分布在雷达反射率为45~65 dBz且VIL≤40 kg·m-2的区域内;45 dBz的雷达强回波核顶高达到6 km可作为闪电预警的参考指标之一。

     

    Abstract: In order to improve the understanding of the characteristics of thunderstorms in Guangxi and better study its forecasting methods, based on the 2022 VLF/LF 3D lightning data and SWAN radar 3D composite data, 1 131 thunderstorm cases were identified and extracted by integrating SCIT (Storm Cell Identification and Tracking) and DBSCAN (Density Based Spatial Clustering of Applications with Noise), and thunderstorm feature data sets were constructed. Based on this data set, statistical analysis was carried out on the characteristics of thunderstorms in Guangxi, such as the spatiotemporal distribution, movement direction, duration, movement speed, and movement distance. Then further analyze the distribution characteristics of radar reflectivity, vertically integrated liquid water (VIL), and echo height in thunderstorm environments. The results are as follows. (1) Thunderstorms in Guangxi are characterized by more in the south and less in the north, with the highest thunderstorm activity in the southern coastal areas. Thunderstorms occur most frequently in summer (June-August), accounting for 65.3%, while they sharply decrease in winter (December-February), accounting for only 0.18%. Thunderstorms mainly occur from 11 ∶00-19 ∶00 BT during the day. (2) The thunderstorms speed was mainly concentrated in the range of 2~16 m·s-1, with the most frequent speed being 4~6 m·s-1. The movement distance was mainly within 100 km, with the most frequent distance being 10~20 km.The dominant movement directions of the thunderstorms were northeast, north, northwest, and east. There are certain differences in both speed and distance among thunderstorms moving in different directions. Specifically, thunderstorms moving eastward tend to be faster (8~16 m·s-1) and travel farther (10~40 km), those moving southward are generally slower (2~10 m·s-1) and travel shorter distances (0 to 30 km); thunderstorms moving in other directions have speeds concentrated 4~12 m·s-1, though with varying peak ranges. (3) The initial flash in thunderstorms often occurs in areas with reflectivity greater than 45 dBz and VIL less than 30 kg·m-2. Lightning after the initial flash is primarily occurs in the 45~65 dBz strong echo region and is highly correlated with VIL in the range of 0.1~40 kg·m-2. The strong echo core which threshold greater than 45 dBz with top height exceeds 6 km can be used as one of the reference indicators for lightning occurrence.

     

/

返回文章
返回