青藏高原东南侧南风的东扩特征分析
投稿时间:2018-06-10  修订日期:2018-07-26  点此下载全文
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作者单位E-mail
祁莉 南京信息工程大学大气科学学院 qili@nuist.edu.cn 
杨睿婷 南京信息工程大学  
何金海 南京信息工程大学  
中文摘要:与东亚季风的风场季节转换特征截然不同,青藏高原东南侧常年盛行南风,且该南风有东扩现象,15侯已到达115°E以东。本文利用再分析资料分析了常年南风区南风东扩时间的年际变化特征,讨论了东扩主要影响因子及其对我国降水的可能影响。研究结果表明,南风东扩时间存在显著的年际变化特征。当2月高原热源偏强时,高原南侧形成的气旋性环流有利于南风较早地东扩。而另一影响因子来自海上,El Ni?o事件时南风区南风东扩偏早且在CP El Ni?o年南风区南风东扩更显著。南印度洋上的负—正—负海温异常自南印度洋激发一反气旋-气旋-反气旋-气旋波列,在高原南侧形成的异常西风加强了高原绕流,有助于常年南风区南风的加强与东扩。值得注意的是,南风东扩的早晚对我国东部气候存在显著的影响。当南风东扩偏晚时,江南春雨偏少,东亚副热带夏季风建立偏晚,2-3月自孟加拉湾南部至菲律宾以东洋面的广大地区降水偏多;6月则出现长江流域北侧降水偏多而南侧降水偏少的偶极型降水异常分布。
中文关键词:常年南风区,东扩,高原热源,海温,降水异常
 
Eastward Extended Features of the Southerly Wind on the Southeast Side of Tibetan Plateau
Abstract:Distinguished from the seasonal variation characteristic of the East Asian monsoon, the south wind prevails all the year over the southeast of Tibetan. This year-round southerly moves eastward and can extend to the east of 115°E in the 15th pentad. By utilizing the reanalysis data, the annual variation features of the time of year-round southerly’s eastward extension are analyzed,the impact factor and its influences on precipitation of China are discussed. Result shows that, the interannual variations of the eastward extension time for the southerly are obvious. When the heating sources over the Tibetan is strong in February, a cyclone circulation forming in the south of the Tibetan contributes to the occurrence of the eastward extension of the year-round southerly. Another factor coming from the ocean,the year-round southerly eastward extends earlier when El Ni?o events appear, and the year-round southerly region extends to the east more obviously during the CP El Ni?o years. A wave train from south India Ocean, which are motivated by the tripolar of sea surface temperature(SST) anomaly in south India Ocean and, enhances the flow around and southerly anomaly,and conduces to the enhancement and eastward extension of the year-round southerly. Remarkably,the eastward extension impact on the climate of eastern China observably.When the year-round southerly puts off extending eastward, the Spring Persistent Rains will be weaker and the East Asian subtropical summer monsoon will delay its onset. In February and March, the precipitation increases from southern Bay of Bengal to eastern Philippines. During June,a South-North dipole-type precipitation anomaly is formed in the Yangtze River Basin
keywords:Ordinary-year south wind,eastward extension,heat source over the Tibetan,SST,precipitation anomaly
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