南海夏季风持续异常的特征及其对全球环流的影响Ⅰ.诊断分析

用1980～1996年OLR资料及NCEP/NCAR再分析资料研究了南海夏季风持续异常的基本特征及其与全球环流的关系.对比分析结果指出,强弱南海夏季风期大尺度环流(副热带高压、局地 Hadley环流及 Walker环流等)变化基本相反.在南海地区出现强弱持续异常的季风活动时,该地区的对流活动不仅与大尺度热带和副热带流场有关,而且还反映出北半球西风带环流的调整.北半球中高纬大气环流对南海夏季风持续异常是有响应的.南海地区季风的强弱,特别是出现持续异常时,强弱季风所对应的动能差异是全球性的,其相应的大气热状态也截然不同.南海夏季风强烈而持续的对流活动明显通过改变大气热源的分布和大尺度垂直环流的结构,影响到更大范围地区的环流状况.

Characteristics of Persistent Anomalies of the South China Sea Summer Monsoon and Its Influences on the Global Atmospheric Circulation

The characteristics of persistent anomalies of the South China Sea Summer Monsoon (SCSM) and its relationship with atmospheric circulation are studied by using OLR and NCFP/ NCAR reanalysis data (1980-1996). Comparative analysis shows that the variation of the large scale circulation (including the subtropical high. Hadley and Walker cells), is basically contrary between the strong and weak SCSM. The persistent anomalies of SCSM not only relates to the tropical and subtropical large scale flow fields, but also reflects the adjustment of the northern extratropical cir-culation. Moreover, the response of large scale circulation in the Northern Hemisphere to the SCSM persistent anomalies is further evidenced. The contrary distribution of kinetic energy for the strong and weak SCSM, especially in their persistent anomaly period, almost covers the whole globe. The apparent heat source and moist sink illustrate a totally different features for those two periods. The intense and persistent convection resulting from strong SCSM would cause a remarkable change of heat source in the atmosphere, and then influence the vertical circulations.