都江堰短时强降水时空分布统计分析

根据气象观测站逐5 min雨量资料的统计结果,分析了四川都江堰地区短时强降水的时空分布变化特征,结果表明：①都江堰各年1 h雨量极值均出现在较高海拔的地区,且1 h雨量极值在当次降水过程总雨量中所占的比重很高，说明都江堰短时强降水的强度非常集中;②受地形与夜间云顶辐射冷却作用,都江堰短时强降水的夜雨特征突出,且后半夜比前半夜多;③都江堰地区夏季的对流过程一般是沿西北山脉迎风坡生成与发展的,随后对流系统发展到东南平原地区;④都江堰短时强降水主要集中在60～130 min,最长可持续210 min。

Temporal Spatial Distribution Characteristics of Short Period Heavy Precipitation in Dujiangyan

The statistical results from the rain gauge data extracted every 5 minutes are used to analyze the temporal spatial distribution variations of short period heavy precipitation in Dujiangyan. The results show： （1） the maximum of hourly rainfall occurs usually in high altitude areas. The maximum hourly rainfall has a big weight in total precipitation in the same event, which reflects that the rainfall in Dujiangyan is characterized by high intensity and concentrative precipitation time. （2） Influenced by the effect of landform and the radiative cooling of cloud tops, short period heavy precipitation in Dujiangyan primarily occurs at night, and there occur more freguently rains after midnight than before midnight. （3） Heavy precipitation occurs first along the windward slope of the mountains in summer, and afterwards，convection systems move towards southeast areas. （4） The durations of short period heavy precipitation in Dujiangyan are calculated. The precipitation duration ranges from 60 to 130 minutes generally, with the maximum up to 210 minutes.