三种不同天气系统强降水过程中分钟雨量的对比分析

The Comparative Analysis of Minute-Class Rainfall on Three Different Heavy Rain Processes

通过使用高时间分辨率的分钟级雨量资料并结合雷达回波,对比分析了近年来飑线、梅雨锋和热带系统影响下的三次强降水过程,并通过降水率、降水持续时间和降水变率的统计,探讨三次强降水过程的特征,最后给出强降水时段对应所有站点最初1小时降水的平均状态。结果表明:用分钟雨量资料辨识出的强降水时段降水序列,结合雷达回波和小波分析发现其可以很好地表现γ中尺度对流系统的降水特征,弥补了小时雨量时间分辨率低的缺陷。分析三个过程中强降水时段的样本发现华北飑线的强降水过程单站只有一次强降水时段,累计雨量基本在50 mm以下,具有降水率大,持续时间短,突变性强的特点,预报难度较大;在热带对流系统的影响下,单站降水由多次强降水时段构成,且强降水时段样本累计雨量可达100 mm以上,降水率较其他系统偏小,但持续时间最长,降水均匀稳定;梅雨锋对应的降水持续时间以1～2 h为主,但降水率高于热带系统,强降水时段样本累计雨量基本在100 mm以下,降水性质的特点是介于飑线和热带强降水系统之间,预报最为复杂。

The minute＇s rainfall data and radar echoes in three heavy rain processes, which are chosen from Meiyu-front, squall line and tropical system respectively in recent years, were used to analyze features of minute-class rainfall distribution. The statistical features of three heavy rainfall processes were discussed through the precipitation rate, duration of precipitation and precipitation changers rate. Finally, the average state of first one-hour precipitation in strong precipitation periods was given. The results showed that minute＇s precipitation series could be a very good performance of precipitation features in meso-γ scale convective system. If combined with the radar echo and wavelet analysis, it could make up for the low time resolution of hour precipitation series. Analysis of samples in three heavy rain processes found that in the squall line, one single station only had once strong precipitation period, and the accumulative rainfall was less than 50 mm almost. It had high precipitation rate, but short duration periods and high variability, therefore, the prediction was difficult. However, under the influence of tropical convective systems, the single station precipitation was composed of many strong precipitation periods, and its accumulated rainfall up to 100 mm. Its precipitation rate was small, but had the longest duration time, and precipitation was more even. For the third heavy rain process, strong precipitation period in Meiyu front system corresponded to duration of 1--2 h, higher rate of precipitation than tropical convective systems, and the accumulative rainfall less than 100 mm. The precipitation nature was between squall line and tropical system, thus the prediction was the most complicated.