摘要
利用1948～2008年NCEP/NCAR逐月再分析资料和1958-2007年中国560站夏季降水资料,设计了一个区域西风指数,探讨了高原夏季风和500百帕中纬度西风带活动的时间-频率多层次年际、年代际时间尺度变化特征以及对我国夏季降水的影响。结果表明:高原夏季风对区域西风带活动具有显著的影响,近61年来,两者总体变化趋势相反,前者增强后者减弱。除了都具有1-2年、27-28年和线性趋势变化的共同周期外,还呈现出各自的周期变化,并且均发生过一次年代际气候跃变现象,前者发生在20世纪70年代中期,后者发生在80年代中期,高原夏季风由偏弱转为偏强,区域西风由偏强转入偏弱,在跃变前后两者各种周期的时间尺度和强度存在明显的不同。如果排除1-2年周期的不确定性,预计接下来高原夏季风将直接进入偏弱期,区域西风指数可能在3-4年后才转入偏强期,并且高原夏季风会比区域西风指数提前发生突变,对区域西风指数具有一定的指示意义。高原夏季风不仅自身对我国夏季降水产生重要的作用,同时,它通过影响中纬度西风带的活动,间接地影响着我国的夏季降水。
Based on monthly NCEP/NCAR reanalysis from 1948 to 2008 and 560-station summer precipitation in Chi- na from 1958 - 2007, we discussed the changing characteristic of time-frequency on interannual and interdecadal time scale of the plateau monsoon and 500hPa westerly activities in mid-latitude, as well as its impact on summer precipita- tion in China. The result shows that： plateau monsoon has a great impact on regional westerly index. Nearly 61 years, the overall trend of plateau summer monsoon and mid-latitude regional westerly index is opposite, the former strengthened and the latter weakened. In addition to common cycles of 1 - 2 years, 27 - 28-year and linear trend, they also show changes in their own cycle. Both have an interdecadal climate mutation, the former occurring in the middle 1970＇s from weak to strong, the latter in the middle 1980＇s from strong to weak. Before and after of change, the time scales and strengthen of all kinds of cycles are obviously different. If the uncertainty of one-two-year cycle is excluded, it can be estimated that the plateau summer monsoon will be directly access to a weak phase and the region- al westerly will be in a strong period after 3 -4 years later, and the time of plateau monsoon mutation will probably be earlier than the regional westerly index＇ s, which has a certain indicative significance to the latter. The plateau summer monsoon not only has a direct impact on the summer precipitation in China, but also has an indirect influence by affecting mid-latitude westerly activities.
出处
《成都信息工程学院学报》
2010年第1期61-68,共8页
Journal of Chengdu University of Information Technology
基金
国家自然科学基金资助项目(40375031)
关键词
小波变换
多时间尺度
高原季风
区域西风指数
年际年代际变化
中国夏季降水
plateau monsoon
regional westerly index
interannual and interdecadal changes
the summer precipitation in China
wavelet transform
multi-time scale
