Study On The Characteristics Of Lightnin Activity And Risk Zoning Of Lightning Disaster In Shandong Province

Shandong, which locates at the eastern coast, is one of the high lightning disaster incidence areas in China due to the frequent severe convection weather. Based on the data of thunderstorm day, lightning location and lightning disaster information, the characteristics of the spatial and temporal distribution of the thunderstorms and lightning flashes as well as lightning disasters in Shandong Province have been analyzed in detail in this paper by using several statistical methods, such as linear tendency analysis, Morlet wavelet analysis and Mann-Kendall methods, etc., furtherly the lightning disaster risk diagram of Shandong province has been provided through lightning disaster risk analysis.(1)There is a close relationship between the spatial distribution of thunderstorm day and the geographical condition and the underlying surface characteristics in Shandong province,and more thunderstorm days occur in the central area, while less ones in the eastern and western areas. The annual average thunderstorm day in the central area is more than25days, which makes the central area the medium thunderstorm activity region; while the annual average thunderstorm day in the eastern and western areas is less than25days, which makes the eastern and western areas the less thunderstorm activity region. The annual average thunderstorm day in Shandong Province is25days, showing a trend of fluctuating downward from1967to2011.There are two abrupt change points in1979and1999, which separate the whole process into3periods:declining phase, stable phase and another declining phase. In the past45years, there are is one primary period of24year and one secondary period of9year of the thunderstorm activity in Shandong Province.(2) The cloud-to-ground (CG) lightning activity in Shandong Province is influenced by different geographical condition, terrain, underlying surfaces, altitude and monsoon climate, and appears significant differences in spatial distribution. The CG flashes in the southern area are more than that in the northern area, more in mountain areas than in plains, and more in inland areas than in coast areas. CG flashes usually occur near the mountains and bodies of water. It is found that the majority of CG flashes are negative, occupying98.52%of the total, which is about348.7thousand times per year; while the positive CG flashes account for only1.48%of the total amount. There are obvious seasonal variation and diurnal variation in CG lighting flashes.The CG flashes occur more frequently in summer, especially in August, and the CG flashes appear frequently during afternoon and reach the peak during16-17h (Beijing Time).The average current intensity of CG flashes is about11.61kA, among which, the average current intensity of positive CG lightning is about25.10kA, and the negative CG lightning is11.41kA.(3) Based on the statistics of the lightning disaster, lightning disaster events occur mostly in summer, accounting for79.50%of the total amount. From2004to2011,there were161personnel casualty events caused by lightning strikes, which led to the death of156people and the injury of105people. The types of lightning disaster are related to the economic development and the level of urbanization of the cities. For example, personal casualty accidents caused by lightning strikes occur mainly in rural areas, and equipment damage and serious economical damage occur mainly in city areas.(4) A disaster risk evaluation index model is designed with the guidance of disaster formation theory, which is consist of hazard, hazard formative environment, hazard affected bodies, disaster prevention capacity and their interactions. After that, the lightning disaster risk situation in Shandong is analyzed and the Shandong Province lightning disaster risk diagram is produced on the base of the GIS spatial analysis technique, AHP and WCA methods.At last, all the areas in Shandong are divided into five risk categories:high, secondary high, medium, secondary low and low respectively. The central Jinan, southern Zibo, Laiwu, central Qingdao, southern Binzhou, central Jining, southern Linyi and southwest Heze are the districts of the highest risk level, the eastern Taian, northern Linyi and Rizhao are the districts of secondary high risk level, the northern Binzhou, northern Jinan, western Taian, Dongying, Weifang and Yantai are the districts of medium risk level, the northern Qingdao, eastern Liaocheng and eastern Dezhou are the districts of the secondary low risk level, the north Heze, western Liaocheng and southwest of Dezhou are the districts of the lowest risk level.