Studies On Temporal And Spatial Variations Of Thunderstorm Day In Jiangsu And Lightning Prediction In Nanjing

Lightning can cause not only endanger human' lives but also hazards aviation, electric power, computer network and building. Lightning detection and prediction become a part of meteorologic service by setting up lightning detecting net. At the same time, application research and product exploitation of lightning data play an important role of disaster weather forecast, which show extensive useful foreground. Therefore, it is important to study lightning evolvement and distributing characteristic, especially to explore appropriate prediction method. Lightning prediction work is significant in preventing calamity and also in enhancing meteorologic service.Climate character of thunderstorm activity is very important in thunderstorm study. It reflects spatial and temporal distribution of thunderstorm activity .Climate character of thunderstorm activity is also significant to lightning protection work. Moreover, long-playing data should be accumulated in thunderstorm climate research, for long-playing data will have typical climate representation. Usually ten years data is least needed. The article statistically studies the climate characters of thunderstorm in Jiangsu Province using the data of thunderstorm days of thirty years. The result helps to understand thunderstorm activities over Jiangsu Province, and supplies theoretical reference on surveillance of lightning, and also offer practicality of lightning protection. The article is useful for Nanjing region's thunder and lightning prediction and real time protection simultaneously based on lightning location system (LLS) data and radiosonde data. Using the observational data of thunderstorm days of sixty stations in Jiangsu Province from 1971 to 2000, the characteristics of the thunderstorms over Jiangsu are studied by means of empirical orthogonal function (EOF) method and the Morlet wavelet analysis. EOF has been proved to be original in analyzing the characteristic of spatial distribution and temporal variety of meteorologic field. It has property of quick convergence, so, several former eigenvector can describe the characteristic of variable field. A Wavelet Analysis is a new technology of signal disposal in recent ten years and is useful in numerical value management. The results show that the mean annual number of thunderstorm days in whole area of Jiangsu Province had a decreasing trend during last 30 years. The south thunderstorm days variable gradient is greater than the north variable gradient, based on this, the southeast and the northwest has opposite trend. The changing of thunderstorm days has a certain periods. At last, along with the lightning flash data of Jiangsu province in 2004 and 2005, this article analyzes the detecting efficiency of the lightning flash ,further more, According to the data of lightning location system of Jiangsu province, this article analyzes the regulation of the lightning flash of Jiangsu province in 2005, and along with the radiosonde data of Nanjing, the situation of the lightning flash within the domain of 1°×1°grid around the city ,and the time during releasing balloon-sonde twice a day during 7:15 to 8:15 and 19:15 to 20:15. The results showed that Showalter index, difference of pseudo-equivalent potential temperature (θse) between 700hpa and 1000hpa level,θse difference of 500hpa and 700hpa level, temperature of 1000hpa level and temperature of 500hpa level, these factors have been found with obvious effect on lightning flash early warning in the city of Nanjing. This article also defines the lightning flash index of probability, which gives primary forecast ofthe lightning flash would happen in 0-30 minutes. This article is divided into sixchapters. In the first chapter, the developing process of lightning detecting technology and the effort in lightning study are introduced. In Chapter2, The theory and character of ADTD lightning location system is presented , which is manufactured by Chinese Academy of Science. In Chapter 3, the lightning localization theory has been introduced. In Chapter 4, the characteristics of the thunderstorms over Jiangsu are studied by means of empirical orthogonal function (EOF) method and the Morlet wavelet, statistics results are given by using the lightning observational data of Jiangsu Province. In Chapter 5, besides the data of lightning location system of Jiangsu province, the radiosonde data of Nanjing are used to predict lightning in short-time forecast. In the last chapter, the remaining problems in the study are pointed out and a tentative plan for the future study is outlined.