摘要
利用西安市1971-2013年7个县区逐日降水资料,根据百分位值方法定义不同县区的极端降水阈值,利用平均值法计算全市气候背景和局地变化,应用线性趋势分析法检验序列的变化趋势,对西安夏季极端降水事件的时空分布特征进行分析;并选取7个县区2004-2013年的逐日降水量、逐时降水量,分析西安市暴雨日及短时强降水的时空分布特征;最后探讨其城市化的影响。结果表明,西安市极端降水阈值根据下垫面差异略有不同,中到大雨为极端降水事件的标准;极端降水阈值空间分布与年降水总量的分布相似;强降水多发区与阈值高值区基本对应,极端降水和极端雨日的多发区集中在山区。近43年西安夏季极端降水事件平均强度及频数呈增加趋势,20世纪80年代、21世纪以来极端降水平均强度大、极端降水天数多;西安市极端降水事件具有明显的局地性特征,与夏季降水量的时空分布吻合。西安市极端降水强度表现为市区、中部呈减少趋势,周边呈增大趋势;频数表现为北部、东南部呈减少趋势,中部、西南部呈增加趋势。近10年西安暴雨季节多出现在5月下旬-10月上旬,西部、南部、东部县区暴雨日发生频数较高;西安短时强降水7-8月最为活跃,南部山区多于北部,表现为明显的夜雨型特征,自5月起随时间从中部向东西部扩展,8月扩展至最大,9月迅速收缩;10 mm≤1 h降水量〈20 mm的短时强降水7月多于8月,1 h降水量≥30 mm的短时强降水8月多于7月。2000年前西安的发展处于城市化缓慢期,2000年后为快速城市化时期;城市周边县区的极端降水强度受城市发展的影响最大,城市化缓慢期东南县区的极端降水频率受城市化影响较大,城市化快速发展期西部县区受城市化影响较大。
Based on 7 stations daily rainfall data of Xi＇ an City from 1971 to 2013, according to the percentile value methods with different stations of extreme precipitation threshold, using the method of average to calculate the city climate background and local change, the sequence change trend was inspected with the method of linear trend analysis. The time and space distribution characteristics of Xi＇ an summer extreme precipitation events were analyzed; selecting the＇ daily and hourly precipitation of 7 counties from 2004 to 2013, the spatial and temporal distribution characters of Xi＇ an City rainstorm day and short-time strong precipitation were analyzed; finally the influence of urbanization was discussed. The results showed that ： The extreme precipitation threshold according to the different underlying surface is slightly different in Xi＇ an, moderate rain to heavy rain is extreme precipitation events in standards ; spatial distribution of extreme precipitation threshold is similar to the distribution of the total annual precipitation; strong precipitation prone areas and the high value area basically corresponding threshold, extreme precipitation and extreme rain day incidence of concentrated in the mountainous area. In recent 43 years, summer extreme precipitation events average intensity and the frequency is increased in Xi＇ an; in the 1980 s and the 21 st century, extreme precipitation average strength, extreme precipitation days more ; the extreme precipitation events has obvious local characteristics in Xi＇ an, match the space-time distribution of xi＇ an summer rainfall. In the middle of downtown, extreme precipitation intensity decreased, the extreme precipitation intensity surrounding showed a trend of increase;The frequency of southeastern North, showed a decreasing trend, central,southwest frequency increased. Nearly 10 years of Xi＇ an storm season appear in late May and early October, most western, southern, eastern counties of rainstorm days with high frequency ; short time strong precipitation in Xi＇ an from 7 to August is the most active, southern mountains more than the north, the performance for the night rain features, since May with time extending from the middle to the East and West, August extended to the maximum, September rapid contraction; 10 mm ≤1 h rainfall 〈 20 mm short time strong precipitation in July more than in August, 1 h precipitation ≥30 mm short-time strong rainfall in August than in July. 2000 years ago, Xi＇ an show period in slow development of urbanization, after 2000 years, Xi＇ an show period in rapid urbanization ; urban development has been the biggest influence on extreme precipitation intensity in the city surrounding counties, southeast district of extreme precipitation frequency greatly influenced by the urbanization in slow urbanization period, western counties are greatly influenced by urbanization in rapid urbanization development.
出处
《安徽农业科学》
CAS
2015年第25期197-201,204,共6页
Journal of Anhui Agricultural Sciences
基金
2014年陕西省气象局预报员专项(2014Y-13)
2013年陕西省气象局火车头项目(2013Y-19)
关键词
西安
极端降水
时空分布
城市化
Xi＇an
Extreme precipitation
Time and space distribution
Urbanization
