近10a气候变化影响下四川山地暴雨事件的演变特征

Evolution characteristics of mountain rainstorms over Sichuan Province in the past ten years under the influence of climate change

利用近10 a(2010—2019年)国家气象基本站与加密气象自动站降水资料从气候态探究了四川省山地暴雨事件的空间分型与时间变化特征。在将四川山地暴雨事件划分为川西暴雨(SC-A)、川东北暴雨(SC-B)和川西、川东北两地并发型暴雨(SC-C)这三种类型的基础上,统计分析得到以下结果:(1)近10 a四川山地暴雨的频次略有减少,但累计降雨量和地质灾害却有所增加。SC-A近10 a发生的频次和强度呈增加趋势,而SC-B表现出不规则的振荡趋势。在三类暴雨事件中,SC-A在发生频次和强度上均为四川山地暴雨中最高的一类。(2)暴雨峰值逐年变化中,SC-A暴雨峰值雨量总体大于另两类暴雨,近10 a中,峰值雨量除在8月呈上升趋势外,其余月份山地暴雨强度无明显的线性增减趋势。(3)三种类型的山地暴雨事件累积雨量和频次变化趋势比较一致,5—7月逐渐增加,7月达到最高,8—9月逐渐下降。5月和9月发生的暴雨事件主要为SC-B山地暴雨,6—8月则为SC-A山地暴雨为主。(4)四川山地暴雨事件夜间出现暴雨峰值的频次远高于白天,主要集中在北京时00—06时,在研究的三种类型山地暴雨事件中,SC-A的夜间暴雨峰值出现次数最多。

Based on the precipitation data from national meteorological stations and intensive automatic weather stations in Sichuan Province over the past ten years(2010-2019),the temporal evolution of mountain rainstorms in climate scale over Sichuan are studied.By dividing the rainstorm events into rainstorms in western Sichuan(SC-A),rainstorms in northeastern Sichuan(SC-B),and rainstorms in western and north⁃eastern Sichuan(SC-C),statistical analysis yielded the following results:(1)The frequency of mountain rainstorms in Sichuan over the past 10 years shows a decreasing trend year by year,which is in contrary to the trend of accumulated rainfall and geological disaster.Both the fre⁃quency and intensity of SC-A shows an increasing trend in the past decade and the SC-B shows a trend with irregular fluctuations.At the same time,the SC-A shows a higher frequency than the other two events.(2)In the annual change of rainstorm peak,SC-A rainstorm peak is generally higher than the other two types of rainstorm.During the 10 years,except for the increase trend in August,the peak rainfall intensity in other months has no obvious linear increase or decrease trend.(3)The trends of accumulated rainfall and frequency of the three types of mountain rainstorm events were consistent,increasing from May to July,reaching the highest in July,and then gradually decreasing from July to September.The main feature is that the heavy rains in SC-B occur during May and September while the heavy rains in SC-A occur from June to August.(4)The frequency of strong precipitation at night is much higher than that during the day,mainly at 00-06.Furthermore,strong precipitation at night is more likely to occur in SC-A among the three types of mountain rainstorms.