PJ遥相关型对长江中下游夏季降水影响的不对称性研究
投稿时间: 2018-03-15  最后修改时间: 2018-04-02  点此下载全文
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作者单位E-mail
陶丽 南京信息工程大学大气科学学院 taoli@nuist.edu.cn 
于国强 南京信息工程大学大气科学学院  
基金项目:国家重点研发计划项目(2016YFA0600402),国家自然科学基金(41630423,41375098)江苏高校优势学科建设工程资助项目(PAPD)
中文摘要:利用1979-2015年多种海洋和大气资料,分析了PJ遥相关型在不同位相时长江中下游夏季降水异常分布的特征,讨论了引起降水变化不对称性的可能原因。结果表明降水异常分布的不对称性包括位置不对称和强度不对称。在PJ负位相年(对应El Nino次年),长江中下游降水显著增多,两个降水极大值带分别位于江淮流域和日本南部。而在PJ正位相年(对应La Nina次年),长江中下游降水减少却并不明显。PJ型影响下的海温在前冬季呈现典型的ENSO型特征。分析发现在PJ负位相年中东太平洋、印度洋、南海地区海温距平要强于PJ正位相年这些地区的海温距平。PJ负位相年,印度洋海温偏暖,在菲律宾海有异常反气旋,长江中下游地区有异常气旋,PJ正位相年则相反。但PJ负位相年的菲律宾海异常反气旋、长江中下游地区异常气旋的强度要强于PJ正位相年的菲律宾海异常气旋、长江中下游地区异常反气旋的强度。利用大气环流模式ECHAM4.8进行数值实验,结果表明即使偏暖的印度洋海温距平和偏冷的印度洋海温距平相同,但是偏暖印度洋海温距平在热带西北太平洋激发的反气旋环流要强于偏冷印度洋海温距平激发的气旋性环流,从而造成长江中下游地区降水偏多要强于其偏少程度。这说明相对于干旱长江中下游夏季更易发生洪涝。
中文关键词:PJ遥相关,夏季降水,不对称性
 
Asymmetric effect of Pacific-Japan pattern on summer precipitation in Middle and lower area of the Yangtze River
Abstract:The燾haracteristics爋f爐he燼nomalous燿istribution爋f爏ummer爎ainfall爋ver middle and lower area of the Yangtze River during different phases of PJ teleconnection patterns燼re燼nalyzed燽ased爋n爒arious爋ceanographic燼nd燼tmospheric data from 1979 to 2015, and爐he爌ossible燾auses爁or燼symmetric爌recipitation燾hanges燼re燿iscussed. The result show that asymmetry of anomalous precipitation distribution includes asymmetric position and intensity. In the negative phase of PJ (El Nino decaying year), precipitation in the middle and lower reaches of the Yangtze River increased significantly, with the two maximum precipitation zones located in the Yangtze River and the southern Japan. In the positive phase of PJ (La Nina decaying year), the precipitation in the middle and lower reaches of the Yangtze River did not decrease obviously. The燾haracteristics爋f燬ST are similar to ENSO in the previous winter of PJ. It is found that during the negative PJ phase, the SST anomalies in the eastern and central Pacific, Indian Ocean and South China Sea are stronger than those in the PJ positive phase. In the PJ positive phase, the warm SST over the Indian Ocean excite an abnormal anticyclone in the Philippine sea, and an abnormal cyclones in the middle and lower reaches of the Yangtze river. It is vice verse in the PJ negative phase. But the abnormal anticyclone in the Philippine sea and the abnormal cyclones in the middle and lower reaches of the Yangtze river in PJ negative phase are stronger than the abnormal cyclone in the Philippine sea and the abnormal anticyclone in the middle and lower reaches of the Yangtze river in PJ positive phase. Numerical simulations using the atmospheric circulation model ECHAM4.8 show that the precipitation in the middle and lower reaches of the Yangtze River is stronger than its less degree even though the warm SST anomalies and the colder SST anomalies over the Indian Ocean are equal, the anticyclonic anomalies over the Philippine Sea excited by the warm SST over the Indian Ocean is stronger than the cyclonic anomalies excited by the cold SST over the Indian Ocean. This shows that it is more prone to floods than the dry summer in the middle and lower reaches of the Yangtze River.
keywords:Pacific-Janpan pattern, summer precipitation, asymmetry
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