甘肃省短时强降水的时空特征

基于甘肃省81个自动气象站2002—2012年逐小时降水数据,分析了甘肃省近11 a来短时强降水的时空变化特征。结果表明:短时强降水频次自甘肃省西北向东南逐步递增,陇东南地区是甘肃省短时强降水发生频次最多、强度最强的地区。短时强降水存在2个高发中心,一个在以合水为中心的陇东地区,另一个在以徽县为中心的徽成盆地。短时强降水主要发生在午后至前半夜,出现时段集中在16:00—00:00,17时前后是短时强降水天气高发时段。短时强降水主要出现在5—9月,其中7—8月是一年中出现最多的月份,其次是6月。近11 a来,短时强降水频次呈上升趋势,2006年和2010年出现了2个峰值,其中2010年最多,发生52次,2004年最少只有17次。

The Temporal and Spatial Distribution Characteristics of Short-duration Heavy Rainfall in Gansu Province

Short-duration heavy rainfall (SDHR) forecasting is important and difficult in severe convective weather forecasting. Especially in Gansu Province, the arid and semi-arid area, a severer disaster can be brought about by SDHR. Based on the hourly precipitation data on 81 stations in Gansu Province from 2002 to 2012, the characteristics of SDHR are studied in the spatial and temporal variation. The results show : in Gansu Province, SDHR mainly occurs in Hedong area of Gansu Province, the occurring frequency of SDHR gradually increase from the northwest to the southeast, SDHR is the most intensive in the southeast parts of Gansu Province. There are two centers of high value, and one in Heshui county, located in eastern parts of Gansu Province, another in Huicheng basin located in Hui county. SDHR is concentrated in May to September, especially in July and August. The interannual variations of SDHR show that the frequency of SDHR increased from 2002 to 2012, and with peaks in 2006 and 2010. SDHR occurred most frequently in 2010 with 52 occurrences, and only occurs 17 in 2004. SDHR mainly occurs during the night, especially in the early night, concentrated in the period between 16:00 to 00:00, with high-incidence time around 17:00. Anomalous south winds and enhanced water vapor transport are important circulation backgrounds for SDHR.