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利用华北地区1961～2005年逐日降水数据资料,统计分析了华北地区作物生长期暴雨强度和暴雨过程发生的时空分布特征。结果表明,华北地区作物生长期暴雨强度和暴雨过程具有明显的年际波动和年代变化特征;华北地区虽然年年都发生暴雨和大暴雨,但年际变化较大,变异系数分别高达36.9%和53.1%;特大暴雨每4～5年发生1次,暴雨过程则平均11年一遇,特大暴雨和暴雨过程虽然只发生在较少的年份,但年际间波动更加明显;20世纪60年代是暴雨强度较大和暴雨过程多发期的峰值区,而1999年以后暴雨强度和暴雨过程则处于1961～2005年历史阶段的低值区;70～90年代则处于两者之间,期间不同强度暴雨发生并不同步。此外,华北地区年均暴雨日数空间分布呈现从西北向东南明显增加的趋势,暴雨日数变异系数则呈现自东南向西北逐渐增大的趋势。一般地,年均暴雨日数越多,变异系数越小,反之亦然。统计还表明,华北地区降水量与暴雨日数之间存在明显的正相关关系。
Based on the daily precipitation data from 1961 to 2005 in North China, the temporal and spatial distribution characteristics of storm intensity and torrential rains during the crop growing season in North China were statistically analyzed. The results showed that the intensity and storm process of rainstorm during the crop growing season in North China had obvious interannual fluctuation and chronological variation. Although heavy rains and heavy rainstorms occurred annually in North China, the annual variation varied greatly with the coefficients of variation as high as 36.9% and 53.1 %; Heavy rainfall occurred once every 4 to 5 years, while heavy rain occurred an average of 11 years. The heavy rainfall and heavy rainfall occurred only in a few years, but the fluctuation was more obvious in the inter-annual period. The heavy rainfall in the 1960s Intensity and heavy rainfall during the peak period, and after 1999, the intensity and torrential rainstorms in the history of the 1961-2005 period in the low value area; 70 to 90 years are in between the two during the occurrence of different intensity heavy rain and Not synchronized. In addition, the spatial distribution of mean annual number of rainstorms in North China tends to increase significantly from northwest to southeast. The coefficient of variation of the number of rainy days shows a trend of increasing from southeast to northwest. In general, the greater the annual average number of rainstorms, the smaller the coefficient of variation and vice versa. Statistics also show that there is a clear positive correlation between the precipitation in North China and the number of rainstorm days.