| Thunder and lightning is instantaneous electric discharge phenomenon in the atmosphere. It has characteristics of strong current, high temperature and strong electromagnetic radiation etc. Lightning has a great destructive force, with modern social information level continuously improving; lightning disaster is becoming more and more serious. The climate characteristics of lightning activity is an important aspect of the lightning research, it reflects spatial and temporal distribution of lightning activity. Application of lightning detection system play an important role of scientific and accurate prediction work, and provide source data for meteorological service.According to the historical data, Nantong region is one of the regions in Jiangsu coastal area hit most frequently by thunders and lightning, where lightning causes several casualties and economic losses worth of at least one million Yuan each year.It is important to master of laws of thunder and lightning activities and risks from thunder and lightning related disasters.According to the data of lightning location system of Nantong for2008-2010, this paper make a statistical analysis on spatial distribution and temporal variety of meteorological field, and using GIS technology studies the characteristics of lightning activity of Nantong region, and the influence of various factors of the distribution. Application research of lightning data play an important role of lightning disaster forecast, which show extensive useful foreground. Lightning prediction work is significant in improving the level of preventing lightning disaster and also in enhancing meteorological service. Analysis from three aspects, such as climate characteristics of lightning activity, intensity of lightning and density of lightning, the result helps us to understand lightning activities over Nantong region, and supplies theoretical reference on surveillance of lightning, and also offer practicality of lightning protection. Using the data of and the mathematical statistics method, we analysis spatial and temporal distribution of lightning activity. The results appear as shown below:(1) There is a certain regularity in the time of lightning activity of Nantong region. During15:00-20:00, lightning occurs at a higher rate. Since every February it have increased a great deal of lightning activity, reached a peak in August.(2) The intensity of lightning is on the increase each year. According to the statistics, it shows that negative lightning as the principal. From2008to2010, negative lightning frequency in Nantong region accounts for95.2%of all lightning and far higher than positive lightning for4.8%.The main concentration of lightning current amplitude is about60kA and below. The average of negative lightning current magnitude is much higher than that of positive ground lightning.(3) It is shown that the area of Yangtze River have a higher risk, on the hand, inland plain area have a lower risk.Greatly influenced by human activities, urban heat island effect and development, all of those factors above are to some extern to face up to the ethical questions raised the intensity of lightning. There are some correlations density of lightning and disasters, but the intensity of lightning is not generally associated with disasters. Owing to the influence of the land-sea distribution and town-country distribution, lightning activity increase a great deal at the riverside and coastal areas. With the development of the city, urban surface temperature has obvious rise. According to the data, these changes have caused the average temperature to rise by0.11℃per year. And the annual wind speed has reduced around0.32m per second on average.(4) According to the results of lightning disaster risk zoning, it is shown that the area of Yangtze River have a higher risk, on the other hand, inland plain area have a lower risk. The conclusion is that Chongchuan and Gangzha districts are regions with higher lightning risk and the rest are medium lightning risk. |
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