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陕西省汛期极端降水时空演变特征

  

  1. 1.陕西省西安市气象局,陕西 西安 710016;
    2.成都信息工程大学大气科学学院,四川 成都 610225
  • 出版日期:2016-12-30 发布日期:2016-12-30
  • 作者简介:王雯燕(1972-),女,陕西大荔人,高级工程师,主要从事综合观测数据分析应用研究. E-mail:xawwy@163.com
  • 基金资助:

    公益性行业专项(GYHY201306045)和全国新增千亿斤粮食气象保障工程项目“自动土壤水分观测网保障系统”共同资助

Temporal and Spatial Characteristics of Extreme Precipitation in Flood Season in Shaanxi Province During 1961-2013

  1. 1. Xi’an Meteorological Bureau of Shaanxi Province, Xi’an 710016, China;
     2. College of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, China
  • Online:2016-12-30 Published:2016-12-30

摘要:

基于陕西省78个气象站1961—2013年汛期(5—9月)逐日降水资料,统计了陕西汛期极端降水阈值,并利用线性倾向率、Morlet小波分析、经验正交函数分解(EOF)等方法研究分析了汛期极端降水事件的时空演变特征。结果表明:(1)陕西汛期极端降水阈值为25.5~57.5 mm·d-1,平均33.4 mm·d-1,空间上以秦岭为界,以南大部分站点高于平均值,以北低于平均值。(2)汛期极端降水事件频次月际变化较为集中,7月最多,5月最少;年及年代际变化较大,1975—1981年呈增加趋势,1982—1993年呈下降趋势,1993年以后又呈上升趋势,但整体上呈微弱增加趋势,其中关中、陕南地区汛期极端降水事件频次年及年代际变化与全省变化趋势基本一致,而陕北地区年际变化较小,与全省差异较大。(3)各分区汛期极端降水事件频次均存在多时间尺度特征,陕南、关中大尺度和中尺度的时间周期性基本一致,大尺度周期24~32 a,中尺度周期6~10 a,而小尺度周期略有不同;陕北完全不同,大尺度周期26~30 a,中尺度周期15~18 a。(4)陕西汛期极端降水事件频次的第1模态是陕北北部与其他地区呈反位相变化,第2模态是以秦岭为界的南北反相变化,第3模态是关中与陕南、陕北反相变化。

关键词: 极端降水, 汛期, 陕西, 百分位法, EOF

Abstract:

Based on the daily precipitation data of 78 meteorological stations in Shaanxi Province from May to September during 1961-2013, the thresholds of extreme prcipitation in flood season were statistically studied. And on this basis the temporal and spatial characteristics of extreme precipitation in flood season from 1961 to 2013 in Shaanxi Province were analyzed by using linear trend, Morlet wavelet and empirical orthogonal function (EOF) methods. The results are as follows:(1) The thresholds of extreme precipitation in flood season in Shaanxi Province were from 25.5 to 57.5 mm·d-1, the average was 33.4 mm·d-1, and that decreased gradually from the south to the north in space. The thresholds of extreme precipitation in the south of Qinling Mountains were higher than the average, while that in the north of Qinling Mountains were less than the average. (2) The frequency of extreme precipitation in flood season in Shaanxi Province was mainly located in July, while that in May was the least. The annual and decadal variations of extreme precipitation in flood season were obvious during 1961-2013, and the frequency of  extreme precipitation increased from 1965 to 1981, decreased from 1982 to 1993, and increased again after 1993, but appearred a weak increasing trend on the whole. The variation trends of extreme precipitation frequency in central Shaanxi plain and southern Shaanxi during 1961-2013 were consistent with the whole of Shaanxi, while that in northern Shaanxi was relatively smaller. (3) There were multiple scacle periods for extreme precipitation frequency in flood season during 1961-2013. The large-scale and meso-scale periods of extreme precipitation frequency in southern Shaanxi were same as the central Shaanxi, were respectively 24-32 a and 6-10 a, but the small-scale periods of them were lightly different, the former was 2-3 a in the 1980s, the latter was 3-5 a throughout. However the periods in northern Shaanxi were different to other areas, the large-scale period was 26-30 a and meso-scale period was 15-18 a. (4) The variations of extreme precipitation in the north of northern Shaanxi were opposited to other regions under the first mode of extreme precipitation events, that in the north of Qinling Mountains were opposited to the south of Qinling Mountains under the secondary spatial mode, and that in central Shaanxi plain were opposited to the north and south of Shaanxi under the third spatial mode.

Key words: extreme precipitation, flood season, Shaanxi, percentile method, EOF

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