基于闪电聚类方法的西北太平洋区域雷暴活动特征

利用2010-2018年全球闪电定位网(WWLLN)观测资料,采用基于闪电密度的空间聚类算法(DBSCAN)建立了西北太平洋地区雷暴数据集,研究了该区域雷暴的时空分布特征,并进行海陆差异对比.研究结果表明,在合理设定DBSCAN参数阈值的条件下,基于WWLLN闪电聚类的雷暴与天气雷达观测在时空分布和过程演变上具有一致性...

CHARACTERISTICS OF THUNDERSTORM ACTIVITY IN THE NORTHWEST PACIFIC BASED ON LIGHTNING CLUSTERING METHOD

Based on lightning data from the World Wide Lightning Location Network (WWLLN) from 2010 to 2018, and the algorithm of Density-Based Spatial Clustering of Application with Noise (DBSCAN), this study establishes a thunderstorm dataset of the Northwestern Pacific. The temporal and spatial distribution characteristics of thunderstorms in this region are studied, and the characteristics of thunderstorms over land and ocean are compared. The results show that when the parameter thresholds of the DBSCAN algorithm are reasonably performed, the temporal and spatial distribution and evolution of thunderstorms based on WWLLN lightning clusters are consistent with the observations of weather radars. The average daily number, the average area of lightning cluster, the average extension scale, and the average lightning frequency of thunderstorms in the Northwestern Pacific region are 3869, 557.91 km2, 31.99 km, and 33 str/(h·thu), respectively. In terms of spatial distribution, thunderstorm activities are the most intense in the coastal areas of Southeast Asia and tropical islands. In addition, thunderstorm activities in the South China Sea are stronger than that in the deep ocean. The average area of offshore thunderstorms increases with the shortening of its distance from the coastline. As for seasonal variation, thunderstorm activities throughout the region reach their peak in summer (June to August) with the peak of that over the South China Sea in June, while thunderstorm activities off the coast of eastern Japan reach their peak in winter. In the southern part of China''s inland areas, thunderstorm activities begin to increase significantly in March and the average area of thunderstorms reaches its maximum at that time; however, the average lightning frequency of thunderstorms reaches its peak in May. In terms of diurnal variation, the distribution of continental thunderstorm activities is typical unimodal, and most thunderstorms occur in the afternoon and evening. The diurnal variation of marine thunderstorms is relatively moderate, and a unique diurnal pattern can be found in the thunderstorm activities in the South China Sea.