关键词: 雷暴, 气候特征, 趋势, 小波分析, 宁夏

Abstract: The daily thunderstorm data of Ningxia during 1961—2005 are used to analyze the climatic change characteristics by methods of mathematical statistics, linear analysis, and wavelet analysis and so on. Some conclusions are drawn as follows: Ningxia is located in the region with middle thunderstorm frequency, and the number of annual mean thunderstorm days is 86.62 days. During the last 45 years, there were 7 years with more thunderstorm days and 7 years with less thunderstorm days; the number of the most annual thunderstorm days was 118 and the least was 65; the inter-annual change range was large. There was a decreasing trend of thunderstorm weather frequency in these 45 years, with a decreasing rate of 3.072 d/10a, and a 3~4 years relatively short period and a 8 years relatively long period viration. Thunderstorm events mainly occurred in March to October, mostly in summer, and especially in July, it has obviously seasonal and monthly change, and the probability was extremely low in winter. The first thunderstorm occurred in mid-April and the last occurred in mid-September by mean; the mean duration between the first and the last in the whole region was about 139 days. There was obvious diurnal variation in thunderstorms occurrence, showing bimodal or unimodal types; most occurred during 11:00—22:00, with high frequency before or after 15:00. The occurrence of thunderstorms has close relationship with the terrain and topography.

Key words: thunderstorm, climatic characteristic, tendency, wavelet analysis, Ningxia