江西省地闪气候特征及其活动强弱评价方法探讨  

CLIMATIC FEATURE OF CLOUD-TO-GROUND LIGHTNING IN JIANGXI AND THE PRELIMINARY STUDY OF EVALUATION METHODS OF ITS ACTIVITY

作　　者：支树林[1] 许爱华[1] 李俊[1] 孙素琴[1] 

机构地区：[1]江西省气象台,江西南昌330046

出　　处：《气象与减灾研究》2012年第2期37-44,共8页Meteorology and Disaster Reduction Research

基　　金：公益性行业(气象)项目(编号:GYHY201006002);中国气象局气象关键技术集成与应用项目(编号:CMAGJ2011Z10)

摘　　要：为科学评价雷电活动强弱和为雷电预报的效果检验提供参考依据,基于2003—2010年江西省闪电监测定位系统资料,分析了逐小时的闪电频数变化,发现0.01°×0.01°经/纬度分辨率格点上的地闪频数最大值出现在2004年9月18日17:00—18:00,为64次/h;相较其他时段而言,16:00—17:00闪电活动最强。基于地闪观测资料、探空及多普勒雷达资料,分析了雷达回波强度与地闪数的相关性统计特征发现,在0.1°×0.1°经纬度网格点上,0℃层以上最大回波强度大值与相应时段内的地闪频数大值常不一一对应,但地闪频数大值多出现在强回波附近。格点上的12 min内的地闪数大都≤60个,以1—20个为最多;地闪数≥40个的格点数则明显减少;对应的0℃层以上最大回波强度集中于35—60 dBz,回波强度≤35 dBz或≥60 dBz的格点数则明显偏少。回波强度介于45—55 dBz的格点数明显大于回波强度>55 dBz以及<45 dBz的格点数,表明这个区间内的闪电活动最强。因此,借助0℃以上最大回波强度可简单地区分闪电活动强弱。For the purpose of scientific description of cloud-to-ground lightning activity and evaluation of the lightning forecast, this paper analyzes the hourly flashes features by using the 2003--2010 lightning data in Jiangxi province. The results show that the most intense lightning activity appeared during 17：00--18：00, Sept. 18 2004, with the hourly flashes amount reaching 64 on the grid of 0.01°×0.01°. The most intense lightning activity occurred during the period of 16：00--17：00. The historical flashes data, sounding data and Doppler radar data are used to analyze the statistic features of the inter-relationship between radar echo intensity and cloud-to-ground lightning frequency. The results indicate that although the maximum echoes over 0 ℃ layer were not always one-to-one corresponding to the highest cloud-to-ground lightning frequency, the higher lightning frequency always occurred adjacent to the stronger echo area. Most flashes in 12 minutes were less than 60, with the majority less than 20, and the grid number decreased rapidly when the flashes exceeded 40. Accordingly, the maximum echo reflectivity over 0 ℃layer concentrated 35--60 dBz. The grid amount with 45--55 dBz reflectivity was larger than those of less than 45 dBz or larger than 55 dBz, which means that the 45--55 dBz reflectivity lightning is strongest. Therefore, the echo intensity over 0℃ layer can be simply used to forecast the lightning activity.

关 键 词：地闪频数 回波强度 相关性 格点 

分 类 号：P427.321[天文地球—大气科学及气象学]