城区与郊区不同地形地貌下云地闪分布规律初步研究

利用上海3台SAFIR3000闪电定位仪的测量数据、计算机软件技术和数据统计方法对上海地区云地闪的分布规律进行了研究,得出了以下结论：①受地形地貌及高大建筑的影响,上海地区的云地闪分布规律是南北多,东西少,城区多,郊区少;②在郊区发生的云地闪密度虽然低于城区,但是其雷电流的平均强度要高于城区;③上海地区14：00-21：00是云地闪发生最为频繁的时间段。雷暴日是用于表征某地雷电活动的频繁程度并据此进行风险评估及确定雷电防护等级的一个重要参数,但此参数在实际应用过程中存在着一些问题,文章提出了用＂闪电密度＂或者＂地闪密度＂代替雷暴日的设想。

Distribution Regularities of Cloud to Ground Lightning Flashes in Urban and Rural Landforms

By means of the software programming and statistic methods, the data collected by three SAFIR3000 thunderstorm sensors are studied. Some useful conclusions about the distribution regularities of cloud to ground flushes in the Shanghai area are obtained: (1) because of the topography and high buildings in Shanghai, there occur more frequently lightning flushes in the north and south parts than in east and west parts, more frequently in the urban areas than in the rural areas; (2) although there are less flushes in the rural areas, the current is more powerful than that in the urban areas; (3) cloud to ground flushes happen mostly from 14:00 to 21:00. The number of lightning days is an important parameter that can be used to express the frequency of local lightning activity, but there are some problems in the use of this parameter in lightning protection grade estimation and risk assessment. A suggestion to replace the number of lightning days with lightning density is presented and discussed.