The characteristics of lightning risk and zoning in Beijing simulated by a risk assessment model

Abstract

Abstract. In this study, the Cloud-to-Ground (CG) lightning flash/stroke density has been derived from the Lightning Location Finder (LLF) data recorded in recent years. Meanwhile, the vulnerability on land surfaces has been assessed by the classification of the building, outdoor area under the building canopy and open-field area, which makes it convenient to deduce the location factor and confirm the protective capability. Then, the number of dangerous lightning event can be estimated by product of the CG stroke density and vulnerability. Although the human beings and all their material properties are identically exposed to lightning, the lightning casualty risk and property loss risk have been assessed respectively due to their vulnerability discrepancy. The analysis of the CG flash density in Beijing revealed that the JuMaHe river-valley in the southwestern region, the ChangPing–ShunYi zone downwind of the Beijing metropolis, and the mountainous PingGu–MiYun zone near the seashore are the most active lightning areas, with densities greater than 1.5 fl km-2 yr-1. Moreover, the mountainous northeastern, northern, and northwestern rural areas are relatively vulnerable to lightning due to the ability of high elevation terrain to attract lightning and the lack of protection measures. In contrast, lightning incidents by indirect lightning are most likely to occur in urban areas with high population density and aggregated properties, and the property damages caused by lightning are more extensive than those in suburban and rural areas. However, casualty incidents caused by direct lightning strokes seldom occur in urban areas. On the other hand, the simulation based on the Lightning Risk Assessment Model (LRAM) demonstrates that the casualty risk is higher in rural, whereas the property loss risk is higher in urban, and this conclusion is also supported by the historical casualty and damage reports.