贵州省汛期短时降水时空特征分析

Spatio-Temporal Characteristics of Short-Time Strong Precipitation in Guizhou Province

利用贵州区域84测站1991—2009年汛期(4—9月)逐小时降水量资料,分别定义各站点的小时降水量的强降水阈值。阈值的分布有两个高值中心,最强中心在西南部望谟站,西北部的强降水阈值较低。同时利用各站点阈值统计19年不同月份的强降水事件频数,其分布显示:4月份东部和中部偏南地区频数较高,5月份频数高值区呈东北—西南向,随后几个月逐渐向西北推进。4—6月事件频数逐渐增大,7月维持,8—9月开始减少。各月强降水事件发生时次统计表明:一天中有三个相对高值时段,23:00—02:00、05:00—08:00和17:00—20:00,而白天强降水事件很少。短时强降水事件发生时次的空间分布表明,西北部的强降水事件多数发生在傍晚到23:00,中部的强降水集中在23:00—02:00,东南部在05:00—08:00。

In order to investigate the characteristics of short-term heavy rainfall in Guizhou Province,the hourly rainfall data from 84 stations in Guizhou through 1991—2009 are analyzed,with defined a threshold value for each station by the method of threshold value.The distribution of threshold value shows that there are two heavy precipitation high value centers,the stronger one is in Wangmo,southwest in Guizhou,while the other one is in northwest of Guizhou.The precipitation event frequency increases gradually during April to June,maintains in July and begins to reduce during August to September.Precipitation often occurs during the three time periods of 23：00-02：00 BT,05：00-08：00 BT,and 17：00-20：00 BT,there is very little precipitation event during daytime.Most of the heavy precipitation events occur in the evening in northwest Guizhou,while in the middle of Guizhou,heavy rainfall is concentrated in the time period of 23：00—02：00 BT,and then in 05：00—08：00 BT in the southeast Guizhou.