【摘要】 用小波分析方法研究了1993年和1994年青藏高原雨季降水的多时间尺度变化特征,结果表明,小波变换对高原上降水从活跃期到中断期之间突变的时间有很好的分辨能力,并发现强弱季风年高原降水的变化特征有很大的差异:即高原降水除了其季节变化外,强东亚季风年(1994年)还有明显的30～60天低频变化;弱东亚季风年(1993年)却是准双周的变化明显。另外,还将高原上降水从活跃期到中断期的变化与同期的NCEP资料作了一些对比分析,发现高原雨季的开始与东亚夏季风爆发可能有一定的联系,即高原东部夏季降水的第一次活跃期与东亚夏季风的爆发时间基本一致。更多还原

【Abstract】 The wavelet transform is of good resolvable ability for the sudden change between active and break periods of the rainfall, and it is found that there is a large difference for the change features of Plateau rainfall between strong and weak monsoon years. A wavelet transform is employed to investigate multi-time scale variations of summer precipitation over Qinghai-Xizang Plateau in 1993/1994. In 1993, the East Asia monsoon is weak and its onset is late, the precipitation of Qinghai-Xizang Plateau mainly occur in July and August, which has characters of the quasi-biweekly variations. In 1994, the East Asia monsoon is strong and its onset is early, which relates to the precipitation of Qinghai-Xizang Plateau in May and June, marked by the 30～60 day oscillations. In addition, comparing with active and break periods of the rainfall and the NCEP data, the beginning of rainy season over Qinghai-Xizang Plateau related to the East Asia monsoon onset very well in two years, which is in good correspondence to the monsoon onset during the first active-rainfall.更多还原