摘要
利用 196 1～ 1999年海温和地温月平均资料 ,定义了一个海陆热力差指数 ,来表示东亚季风环流的纬向和经向海陆热力差异的变化强度 ,研究了夏季指数与东亚夏季风环流场和中国东部夏季降水的年际变化关系。结果表明 :(1)海陆热力差指数可用来表示东亚夏季风的强弱变化。强指数年东亚季风区低空西南夏季风气流和高层的东风气流明显偏强 ,表明这一年夏季风偏强 ,弱指数年反之。 (2 )海陆热力差指数能较好地反映东部季风区夏季降水的异常状况。强指数年 ,雨带偏北 ,江淮流域和长江中下游明显干旱 ,华南、华北降水偏多 ,弱指数年反之。这一降水异常特征可以从强弱海陆热力差指数年的环流场得到解释。 (3)海陆热力差指数所反映的东亚夏季风具有明显的准 2a和 3～ 6a周期的年际振荡 。
An index of land sea thermal difference ( I LSTD ) has been designed to study its relation to the variation of East Asian monsoon circulation in summer.The results are as follows:(1) I LSTD can be used to identify the strength of East Asian summer monsoon.The years of strong(weak) I LSTD are associated with stronger(weaker)summer monsoon circulation.(2)The index also can reflect summer rainfall anomaly over eastern China.In the years of strong I LSTD ,rainfall belt is mainly located over northern China,and obvious drought emerges in Huaihe River valleys and the mid-lower reaches of Yangtze River.However,during the weak years,summer monsoon is weak and summer rainfall belt is located over the mid-lower reaches of Yangtze River.The circulation fields of strong (weak)index years can explain the features of rainfall anomaly.(3)Besides,the I LSTD has obviously QBO and quasi-4-year and interdecadal oscillations.
出处
《气象学报》
CAS
CSCD
北大核心
2002年第2期164-172,共9页
Acta Meteorologica Sinica
基金
国家攀登项目A"南海季风试验"
