Lightning Distribution And Its Potential Forecast Research In The Southwest Region Of Henan Province

Thunderstorms are occurring in the atmosphere with fierce winds, heavy rain, hail and lightning and other weather phenomena, lightning is one of the most intense. Lightning brings the instantaneous high voltage,large current, strong electromagnetic radiation physical effects will bring great destruction in an instant effect. With the development of social economy, information network technology and modem high-tech gradually obtained the widespread application in each domain, lightning hazard degree and caused economic losses and social influence is also growing. The southwest of Henan area including Nanyang, Zhumadian, Xinyang and other cities in the region, due to its special geographical environment, easy to produce severe convective weather, so it belongs to the high incidence area of Thunderstorm in Henan Province. To carry out research on southwest of Henan thunderstorm characteristics of temporal and spatial variation, beneficial to master the law of local lightning activity, for local government defense lightning provide useful basis.In this paper, with the observational thunderstorm data of30stations in southwestern Henan during55years (1951-2005),the change of the Henan Southwest thunderstorm days, monthly change, cyclical regularity and spatial distribution are analyzed by means of mathematical statistics, the wavelet analysis and the empirical orthogonal decomposition method. The characteristics of temporal variation in southwestern Henan are as follows, inter-annual variation range is bigger and stage of change is more obvious, the numbers of thunderstorm days are decreasing. The thunderstorms can occur in all the year, mostly in summer. In the1960s to the early21st century, there exist8years variation of short period and17tol9years of long periodic change. The spatial distribution characteristics in this area are, the whole area of thunderstorms anomaly variation is consistent, but due to the influence of climate characteristics of thunderstorm days, changes to Qinling Mountains-Huaihe line for the community there are differences between the north and the south, while the existence of local features.Use of Henan province2008-2010lightning detection system data analysis of lightning current parameter characteristics in southwestern Henan Province. the study found that the region of negative percentage of flash frequency is far greater than the positive lightning. Positive and negative lightning average intensity are respectively54.25kA and-36.26kA, average steepness are respectively14.13kA·μs-1and-12.56kA·μs-1. The current strength of most of the flash are distributed between20-40kA, after40kA with increasing intensity of lightning flashes, the frequency decreased. The current strength of40-60kA positive and negative flash distribution probability watershed, this range before, the probability occurrence of negative lightning is bigger than the positive one, the next range is less than positive flashes. Henan southwest region lightning frequency distribution presents a single peak state of a double-dip with a high incidence of lightning in the afternoon from14am to20:00, and the morning of6pm to10PM lightning frequency is the lowest value.The use of Southwest Henan55years of temperature data and the Arctic Oscillation Index Analysis of the impact of these two factors on the thunderstorm activity research area:the variation of the research areas of lightning activity is consistent with the local temperature variation, when the temperature is cold(warm) period, which corresponds to the thunderstorm activity presents less (more); the thunderstorm day of change with the change of the Arctic Oscillation Index is basically a negative correlation, the correlation is more significant.BP neural network method and GA-BP method were selected to forecast thunderstorms in Nanyang area, according to analysis of forecast factors, the better atmosphere unstable conditions (the higher K. index, lower SI index), higher energy (larger TT index), dynamic and thermodynamic conditions more good (larger SWEAT and SSI index), the greater possibility of thunderstorms; comparison of the two model predictions, compared with the simple use of BP neural network, the neural network convergence speed, mean square error and forecast accuracy are improved, the GA-BP method, compared with the traditional method of BP neural network are feasibility and superiority in thunderstorm forecast.