摘要
利用ＮＣＥＰ风场资料和候平均向外长波辐射（ＯＬＲ）资料分析了南海区域低层风场与对流活动的关系，在此基础上，采用南海中南部的纬向风平均值来定义南海夏季风的爆发，确定了长序列（１９４９～１９９８）的南海夏季风爆发日期和强度指数，并研究南海夏季风活动的年际和年代际变化特征。结果表明：南海夏季风爆发日期和强度指数呈显著的反相关；５０年来的气候趋势是，爆发日期逐渐偏晚，强度指数逐渐减弱。二者都存在着明显的年际和年代际变化，它们在不同阶段上的波动是各种时间尺度振荡叠加的结果，而年代际尺度具有非常重要的作用。东印度洋海温异常在南海夏季风爆发前后，均与南海夏季风强度指数呈显著的反相关。东太平洋海温异常在南海夏季风爆发之前，与强度指数反相关，而爆发之后，与强度指数正相关。这体现了南海夏季风活动与ＥＮＳＯ事件的密切关系。
The relationships between wind field at low level and convection activities over the South China Sea (SCS) are investigated based on pentad wind and OLR data from NCEP. The onset time and intensity of SCS summer monsoon are determined by area-averaged zonal wind component over central and south SCS. So we possess long-term time sequence of SCS summer monsoon activities for the period of 1949-1998. Interannual and interdecadal variations are examined by using this time series. The results show that onset time of SCS summer monsoon is significantly negative related with its intensity. Climatic tendency for 50-year manifests that the onset date of SCS summer monsoon gradually gets delayed and its intensity gets weak. Both of them displays considerable interannual and interdecadal variability, they are the results that many waves interact on a wide range of timescales, among them do interdecadal timescale waves play important roles. Whether before SCS summer monsoon bursts or not, the correlation between surface sea temperature anomalies (SSTA) over the East Indian Ocean and intensity index of SCS summer monsoon are remarkably negative. However, the correlation of SSTA over the East Pacific with SCS summer monsoon intensity index is negative before onset, but after onset their correlation become positive. These reflect that SCS summer monsoon activities have close relationships with ENSO events.
出处
《气候与环境研究》
CSCD
2000年第4期363-374,共12页
Climatic and Environmental Research
基金
国家科技部攀登项目A"南海季风试验研究"
国家自然科学基金资助项目!49975023联合资助
