1961～2009年四川强降水变化的时空特征

利用四川143个气象站1961～2009年逐日降水资料,采用气候倾向率、Mann-Kendall检验、Morlet小波分析等方法,分析了四川极端降水事件的变化趋势、突变特征和周期性特点,结果表明,近50年来,四川区域性暴雨次数、暴雨日数和极端降水日数呈略微减少趋势,气候倾向率分别为-0.36次/10a、-0.06d/10a、-0.1d/10a,极端降水强度、极端降水量占年降水量的比例呈微弱增加趋势,但极不显著,与我国极端降水趋多趋强的变化特征不一致。5个指数均有明显的25年左右的年代际振荡周期,年际振荡周期5～8年,5个指数都表明当前正处于极端降水事件的多发期。从空间格局看,四川极端降水事件从西向东呈＂增-减-增＂的分布特征,即四川盆地东部和川西南山地及川西北高原呈增多增强趋势,四川盆地西部、北部和南部则呈减少减弱趋势。大部分站点极端降水指数未发生突变,少数发生突变的站点其突变时间均发生在60年代初。

Change Characteristics of Extreme Precipitation Events in Sichuan Province in Recent 50 Years

According to the daily precipitation data of 143 meteorological stations in Sichuan from 1961 to 2009,by using climate trend rate,Mann-Kendall check,Morlet wave etc.methods,the change trend and mutation site and cyclicity were analyzed.The results show that the regional rainstorm times,rainstorm days and extreme precipitation days undergoes a slightly decreasing t rend,the climate trend rate respectively was-0.36 times,-0.06 d and-0.1d per 10 years,intensity of extreme precipitation and its proportion in annual rainfall appear faint increase trend,but highly no significant,it was inconsistent with the change characteristics that the extreme precipitation was increased and enhanced in CHINA.The all five extreme index appear around 25 years interdecadal oscillation cycle,and interannual oscillation cycle about 5-8 years,they show That is currently in more extreme precipitation event period.Look from the spatial distribution,the extreme precipitation event present the characteristics of "increased-decreased-increased" from west to east in Sichuan,that is the extreme precipitation event appear increased and ehhanced trend in Sichuan Basin,Sichuan southwest mountainous region and Sichuan northwest plateau,and appear decreased and weakened trend in west,north and south of Sichuan Basin.The extreme precipitation index was not mutation in most stations,the mutation site was at early 1960s in few station.