1998年东亚夏季风环流相互作用的低频耦合模态及其位相特征

LF COUPLED MODES AND PHASE CHARACTERISTICS OF EASMC INTERACTION IN 1998

利用1998年SCSMEX试验期降水观测资料和NCEP/NCAR再分析资料, 将物理量场在降水EOF分析得到的时间系数上展开,分析东亚夏季风环流低频变化特征。在揭示环流及我国东部降水异常观测事实的基础上,研究了它们之间相互作用的低频耦合模态及其可能机理,并讨论了低频位相变化与长江流域降水的关系,指出暴雨期次级环流是高低空环流相互作用的可能纽带。

By use of the SCSMEX situ observational precipitation and NCEP/NCAR reanalysis data sets, this study discussed the low frequency (LF) variational characteristics of the East Asian summer monsoon circulation (EASMC) with EOF and MSSA analysis methods. The results show that there were some interaction in LF coupled modes while the precipitation and circulation systems were anomaly in 1998, and the rainfall over southern China was related to mid-latitude blocking high, but the rainfall over Yangtze river region was related with EAP teleconnection mode. Evidence suggests that the second circulation cycle may be an important mechanism in torrential rain periods. The relationship between LF phase variability and the precipitation in East Asian monsoon region are discussed.