【作者】 江丽俐；

【导师】 管兆勇；

【作者基本信息】 南京信息工程大学 ， 气象学， 2008， 硕士

【摘要】 利用NCEP/NCAR再分析资料和地面观测站逐月降水和气温资料,使用多种季风指数对比研究了东亚夏季风年际变化与IOD、ENSO间联系的年代际改变,并使用位涡构造了一个新的夏季风位涡指数(I_PV)。采用该位涡指数,对强、弱东亚夏季风年大气热源和外强迫源SST的差异进行分析,并研究东亚夏季风和IOD、ENSO之间联系的年代际改变,讨论其可能成因。结果表明:（1）东亚夏季风指数分别与DMI、NINO3指数的年际变化的联系都呈明显的年代际改变。在80年代及90年代初期与DMI联系较弱之外,其余时段均显示与DMI具有很好的正相关关系。当季风指数与DMI为正相关时,其与NINO3指数则呈负相关,两者对夏季风具有相反的影响。东亚夏季风分别与DMI、ENSO年际变化之间的联系呈现此强彼弱的特点。1972-1982年和1983-1993年两个阶段DMI、ENSO和季风指数的主要周期、海温分布的显著变化,可能导致了海气相互作用过程中环流变化的周期及分布的改变,使得东亚夏季风与IOD和ENSO的关系发生了年代际改变。（2）夏季风位涡指数(I_PV)既具有明确的物理意义,又能很好地反映中国东部夏季降水和季风环流特征,特别是对长江流域夏季降水具有指示作用。（3）根据位涡指数选取得出的强、弱夏季风年的大气热源和热汇的分布情况基本相反。SSTA外强迫特别是ENSO、热带印度洋异常和南海地区的海温异常与东亚夏季风年际异常联系密切。IOD、ENSO分别与东亚夏季风位涡指数的年际变化的联系都呈明显的年代际改变,变化特征与使用张庆云、李建平定义的夏季风指数分析得到的结果基本一致。更多还原

【Abstract】 The inter-annual variability of East Asian summer monsoon and its relationships with IOD, and that with ENSO are discussed through the contrast of many kinds of summer monsoon indexes using the NCEP/NCAR monthly reanalysis dataset . A new East Asian summer monsoon, East Asian Summer Monsoon Potential Vorticity Index (I_PV) is defined. Based on I_PV, the differences of atmospheric heat source andexternal forcing （i. e., SST） between strong and weak monsoon years are discussed. The relationships between East Asian summer monsoon with IOD, and that with ENSO are more discussed using I_PV .The results are summarized as follows:（1） The relationships between East Asian summer monsoon （EASM） and IOD, and that between EASM and ENSO display an inter-decadal variation feature. The association between EASM and IOD remains strong except during the eighties and beginning of the nineties. It is found that IOD and ENSO have opposite effect on EASM. The IOD and ENSO have complementarily affected the EASM. When the IOD-EASM correlation is high, the ENSO-EASM correlation is low. The obvious changes of distributions of sea surface temperature and periods of EASM, IOD and ENSO during 1972-1982 and 1983-1993, which may result in changes of periods of air-sea interaction and circulation, possibly lead to these inter-decadal variations ofrelationship.（2） East Asian Summer Monsoon Potential Vorticity Index (I_PV) have a clearphysical meaning and reveals the characters of monsoon circulation and the rainfall in eastern region of China. Especially it can indicate the anomaly of the summer rainfall in Yangtze River Valley.（3） The distributions of atmospheric heat source in between strong and weak monsoon years are different. The SSTA especially in the equatorial central and eastern Pacific, tropical Indian Ocean and South Sea of China have a relationship with the the annual variability of East Asian summer monsoon. The relationships between East Asian summer monsoon Potential Vorticity Index and IOD, and that between I_PV and ENSO display an inter-decadal variation feature, similar with those using indexes defined by Zhang Qingyun and Li Jianping etc.更多还原