2010-2019年遵义4-8月短时强降水的时空特征分析

该文利用2010—2019年4—8月遵义13个国家站逐时地面降水观测资料,从年变化、月变化、日变化以及空间分布等多个角度进行统计,从不同等级雨强的时空分布进行分析,初步得出了遵义短时强降水事件的时空分布特征:①从短时强降水总频次的空间分布上看,东部发生频次较其余地区高;4月,发生频次地区差异小;5—8月,地区差异大。②从月分布来看,短时强降水高频中心有如下变化:4月集中在东北部、5月在南部和东南部、6月西移北抬到西部和中部、7月西移南压到西部和南部、8月东北移至东北部,高频中心的变化和副热带高压的南北位移有很好的对应。③从年分布来看,短时强降水事件平均每年发生49次,最多的是65次(2019年),最少的是33次(2017年)。4—6月事件频次迅速增加,6月到达峰值,6—8月事件频次开始逐渐减少,74.1%的短时强降水事件发生在夏季,尤其以6月份居多。④从日变化来看,08—13时短时强降水事件发生频次逐渐减少,13时达到一日中最低值,13—07时事件发生频次逐渐增加,有3个峰值,17—19时、20—22时和01—07时,期间有2个短暂的间歇期。4—7月白天平均发生频次较夜间少,8月反之。⑤6—8月是较高等级短时强降水事件的高发季节,尤其以6月份居多,但统计个例中≥70 mm/h的雨强却是在5月份出现。

Analysis of Temporal and Spatial Characteristics of Short-Time Heavy Rainfall in Zunyi from April to August during 2010 to 2019

The hourly ground precipitation observation data of 13 national stations in Zunyi from April to August during 2010 to 2019 were used to make statistics from multiple perspectives including annual,monthly,daily and spatial distribution,and the spatial and temporal distribution of rain intensities of different levels were analyzed.The spatial-temporal distribution characteristics of short-time heavy rainfall in Zunyi were obtained preliminarily through analysis:①From the spatial distribution of the frequency of short-term heavy rain,the frequency of occurrence in the east region was higher than that in the rest of the region;in April,regional difference in frequency is small,but from May to August,the regional difference is large.②From the perspective of monthly distribution,the high-frequency center of short-time heavy rainfall has the following changes:It is concentrated in the northeast in April,in the south and southeast in May,moved from west to the north to west and central in June,in July westward and southward to the west and south,and northeastward to the northeast in August.The change of the high-frequency center corresponded well with the north-south displacement of the subtropical high.③From the annual distribution,short-term heavy rain events occur on average 49 times per year,the highest being 65 times(2019)and the lowest being 33 times(2017).The frequency of events increased rapidly from April to June,reaching a peak in June,and began to gradually decrease from June to August,74.1%of short-time heavy rainfall occurred in summer,especially in June.④Judging from daily changes,the frequency of short-time heavy rainfall gradually decreased from 08∶00 to 13∶00,reaching the lowest value of the day at 13∶00.From 13∶00—07∶00the frequency of rainfall gradually increased,with three peaks:17∶00—19∶00,20∶00—22∶00,and 01∶00—07∶00 in the next day,and there were two short pauses in this period.The average frequency during the daytime was less than that of nighttime from April to July,and so as in August.⑤June to August is the season of high-level short-time heavy rainfall,especially in June.But the rainfall intensity≥70 mm/h in statistical cases occurrs in May.