近54a云南西北地区极端降水频数和强度特征

Analysis on the Frequency And Intensity of Extreme Precipitation in the Northwest Yunnan during Last 54 Years

为探究云南西北地区极端降水的变化特征,采用云南西北地区6个典型的气象站1960~2013年的逐日降水数据,通过百分位阈值选取、线性倾向、小波分析、突变检验、滑动t检验等对云南西北地区近54a极端降水频数和强度的时空变化特征进行了研究。结果表明：年极端降水频数的范围在3.3~11.2 d,自东向西逐渐增大。年极端降水强度的范围在42.6~26.2 mm/d,自北向东南逐渐增大。云南西北地区的极端降水频数总体上是增加趋势,但并不显著。年极端降水频数在80年代末达到最大。极端降水强度也呈现弱增长趋势。年极端降水强度在20世纪60~70年代先出现减少,之后平稳上升。极端降水频数主要有一个6~7 a的短振荡周期,以及11~12 a的中振荡周期和一个27~28 a的长振荡周期。而极端降水强度主要存在一个27~28 a的长振荡周期。年极端降水频数发生了2次突变,1966年由偏多转为偏少,1977年后极端降水量开始增加。年极端降水强度在1979年发生突变,由减少转为增加趋势。

In order to explore the variation characteristics of extreme precipitation in northwest Yunnan. The daily precipi- tation data of six typical meteorological stations in northwest Yunnan were analyzed by using percentile threshold method, linear trend, wavelet analysis, Mann-Kendall test and moving t-test so as to research on the temporal and spatial distri- bution of the change in the frequency and intensity of extreme precipitation from 1960 to 2013. The results showed that the annual frequency of extreme precipitation was 3.3-11.2 d and had the trend increas from east to west. The annual intensity of extreme precipitation was 42.6-26.2 mm/d and had the trend from north to southeast. The frequency of ex- treme precipitation of northeast of Yunnan province presented increasing tendency, the tendency was not obvious. The annual frequency of extreme precipitation reached the maximum at the end of the 80＇ s. The intensity of extreme precipi- tation also presented a weak increasing tendency, the annual intensity of extreme precipitation showed trend during the 60＇ s to 70＇ s, after that had a smooth rise. The frequency of extreme precipitation had a short periodic oscillation, a pe- riodic oscillation and a long periodic oscillation, while the intensity of extreme precipitation mainly had long periodic os- cillation. The annual frequency of extreme precipitation had two abrupt change points, it changed from more to less in 1966 ,then began to increase in 1977. The annual intensity of extreme precipitationed a abrupt change in 1979, from re- due to increas.