陕西省短时强降水时空分布特征研究

Spatio-Temporal Characteristics of Short-Time Heavy Rainfall in Shaanxi Province

对近几年陕西省98个自动站逐小时降水资料统计分析,研究陕西省短时强降水的时空分布特征。结果表明,小时强降水阈值各地不同,≥10 mm/h较适宜于全省短时强降水界定;陕西省短时强降水多以零散分布、阵发性为主,且其对暴雨日具有较大贡献;陕北、陕南短时强降水频次多且强度大,关中地区则相反;秦岭以北地区多在夜晚和早晨出现短时强降水,而秦岭以南地区短时强降水日变化较小。地形和低空急流的日变化对陕西省短时强降水的形成有显著的影响作用。

Spatio-temporal distribution characteristics of short-time heavy rainfall in Shaanxi were explored by analyzing hourly rainfall statis- tics of 98 auto-stations. The results show that hourly heavy rainfall threshold varies from regions, ≥ 10 mrn/h is suitable for defining short-time heavy rainfall in Shaanxi. Local short-time heavy rainfall is characterized by scattered shower, and it contributes a lot to days of heavy rainfall ; short-time heavy rainfall in south Shaanxi and north Shaanxi are characterized by higher frequency and intensity, that in Guanzhong area has much lower frequency and intensity; in the north of Qinling Mountains, short-time heavy rainfall occurs mostly in the evening and morning, but daity variation of short-time heavy rainfall is lower in the south of Qinling Mountains. Terrains and daily changes of low-altitude jet stream have significant influence on the formation of short-time heavy rainfall in Shaanxi Province.