夏季青藏高原“湿池”变化特征的小波分析

Wavelet analysis of variations of moist pool over Qinghai-Xizang Plateau in summer

采用1948-2007年共60年的NCEP/NCAR资料,计算了夏季青藏高原地区的可降水量,并采用小波分析方法对可降水量的变化特征进行分析。结果表明:夏季青藏高原上有一个明显的"湿池",湿池有3个可降水量中心,分别位于高原西南部、高原南侧和高原东南部。湿池3个中心的可降水量变化有着明显的年代际特征,高原西南部以13.9a的周期变化最为明显,高原南侧9.2a的周期变化最为明显,高原东南部时间尺度2.6a的周期变化最为明显。趋势分析表明,高原西南部的可降水量可能开始增加,而高原南侧和高原东南部的可降水量应该依然处于偏少的阶段。

Based on the NCEP/NCAR reanalysis data between 1948 and 2007 the precipitation over Qinghai-Xizhang Plateau in summer are calculated. Using the wavelet method the precipitation is analyzed. The results show that there is a ＂moist pool＂ over the plateau and there are also three moisture centers located over southeastern part, southwestern part and south part of the Qinghai-Xizhang Plateau respectively. The precipitation of the three centers has different decadal change features： 13.9- year period osdllation in the southwestern part, 9.2-year period oscillation in the southern part and 2.6-year period oscillation in the southeastern part. The trend analysis shows that the precipitation of the southwestern part may be increasing and that of the southern and the southeast part may be still lower.