Comparison Analyses of Climate Characteristics of Thunderstorm and Its Variations between Urban and Rural Areas in Beijing

Using thunderstorm data from 1961 to 2007 in Beijing, statistical of tendency rate, polynomial curve fitting, and Morlet wavelet method, comparison analyses of the climate characteristics of thunderstorm and the trend of climate change were given. The results show that: 1）Thunderstorm occurring from March to November had obvious monthly variation and daily variation, which increased abruptly in May, decreased abruptly in September, and reached maximum in July. 2）In contrast to the rural area, the urban area had more obvious phenonmenon that the first day of thunderstorm advanced, the terminal day of thunderstorm delayed, and the period of thunderstorm extented. 3）Annual average days of thunderstorm in the urban area had an extreme opposite variation tendency to the rural area. Although more annual average days of thunderstorm occurred in the rural area, it decreased in a fluctuating tendency. And although less annual average days of thunderstorm occurred in the urban area, it increased in a fluctuating tendency. The increment tendency of annual average days of thunderstorm in urban area was possibly related to greenhouse effection and the increment of days on which relative humidity≥85％. The decrement tendency of annual average days of thunderstorm in the rural area is possibly related to the evident decrement of relative humidity. 4）The variations of annual average days of thunderstorm had multiple period oscillations in both the urban and rural areas, among which 16-18-year and 3-5-year period oscillations were especially obvious.