Liu X.-D.,Nanjing University of Information Science and Technology |
Liu X.-D.,Inner Mongolia Lightning Warning and Protection Center |
Zhang Q.-L.,Nanjing University of Information Science and Technology |
Feng X.-Y.,Inner Mongolia Lightning Warning and Protection Center |
And 2 more authors.
Journal of Natural Disasters | Year: 2010
Using the observational thunderstorm data of 115 stations in Inner Mongolia from 1971 to 2007, the spatiotemporal distribution characteristics and its change law of thunderstorm were studied by means of mathematical statistics and analysis of empirical orthogonal function (EOF). The results show that the mean annual thunderstorm days of whole autonomous region are 28.6d;the annual-average thunderstorm days are less in the north-west region but more in the south-east region, and interannual thunderstorm variability is obvious. The annual number of thunderstorm days has a decreasing trend of 2.09d/10a, but has an increasing trend in Dongsheng area. The seasonal variation of thunderstorm in Inner Mongolia is obvious. The thunderstorm concentrates within the period from June to August and has three or four active centers. The main active area of thunderstorms concentrates on the area to the east of 110°E. The analysis of EOF shows that the abnormal features of spatial distribution of thunderstorm in Inner Mongolia is comprised in several types ; types of entire area , southeast-northwest, latitude and longitude directions. Preliminary analysis shows that water vapor reduction is the main reason for the reduction of thunderstorms.
Liu X.,Inner Mongolia Lightning Warning and Protection Center |
Liu X.,Nanjing University of Information Science and Technology |
Zhang Q.,Nanjing University of Information Science and Technology |
Feng X.,Nanjing University of Information Science and Technology
Gaodianya Jishu/High Voltage Engineering | Year: 2012
In order to analyze the effect of finite conductivity on the rise time and field strength amplitude of radiation field of return stroke radiation field of cloud-ground flash, we calculated the propagation characteristic of lightning return stroke electromagnetic field along the different conductivity in imperfectly ground surface such as wetland, dry land and sand by using the Cooray-Rubinstein algorithm. The results show that, due to the decrease of ground surface conductivity, the observed rise time of lightning radiation field increases obviously, which will affect the error in lightning location by using the method of time lag in arriving peak time, so the relationship formula of rise time and observed distance can be used to calculate the distance of lightning detection or the ground surface conductivity of propagation path. The results also show the lighting magnetic induction intensity amplitude attenuation decays with the ground conductivity decreasing and the observation distance increasing. Lastly, the correction curve was presented for inversion of lightning current after taking ground conductivity situation into the consideration based on the formula commonly used in inverting the strength of lightning current.