北半球冬季大气环流遥相关型的非线性特征
投稿时间:2005-10-19  修订日期:2006-03-29  点此下载全文
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作者单位
韦莹莹 南京信息工程大学, 江苏省气象灾害重点实验室, 江苏, 南京, 210044 
吴洪宝 南京信息工程大学, 江苏省气象灾害重点实验室, 江苏, 南京, 210044 
沈桂凤 南京信息工程大学, 江苏省气象灾害重点实验室, 江苏, 南京, 210044 
基金项目:江苏省气象灾害重点实验室资助项目(KLME060211)
中文摘要:利用NCEP/NCAR再分析500hPa高度场资料,采用EOF和非线性主成分分析(NLPCA,Nonlinear Principal Component Analysis),研究了北半球冬季大气环流遥相关型的非线性特征,并将两种分析的结果与实际观测相比较,结果表明:NLPCA在提取资料场序列的低维非线性相关结构方面比传统EOF有明显的优越性。北半球冬季大气环流的遥相关型有明显的非线性结构特征,特别是EU型和PNA型,当非线性主成分NLPC取正负极值时,EU和PNA型并不是呈现完全的反位相结构。NLPC取负极值时,EU型的活动中心位置比NLPC取正极值时位置偏西,特别是欧亚大陆中部的距平中心,负中心比正中心偏西,强度更强;PNA型的4个距平中心在NLPC取正极值时比负极值时更集中,副热带太平洋的正中心、北太平洋的负中心比NLPC取负极值时的反符号中心偏东,强度更强。
中文关键词:非线性主成分分析(NLPCA)  人工神经网络  EU型  PNA型
 
Nonlinear Characteristics of Teleconnections for Winter General Circulation over the Northern Hemisphere
Abstract:Using the NCEP/NCAR reanalysis data of 500hPa geopotential height during January 1948 to March 2005,the nonlinear characters of teleconnections of the general circulation during winters over the northern hemisphere are investigated in this paper by the means of EOF and Nonlinear Principal Component Analysis.It is concluded that the NLPCA is obvious superior to the EOF in abstracting the lower-dimensional structer in datasets when comparing the results of the two methods with the observational reality.Teleconnections of the general circulation during winters,especially EU and PNA over the northern hemisphere have the clear nonlinear structures.When the NLPC adopts the maximum and minimum values,EU and PNA don't show the complete antisymmetric responses both in spatial pattern and intensity.When the NLPC takes the minimum value,the pattern of EU locates west of the position when the NLPC takes the maximum value,and in particular the negative anomaly center over the central Eurasia has a stronger intensity than its counterpart-the positive anomaly center.And When the NLPC takes the positive value,the four anomalies of PNA are more concentrative than those of PNA when the NLPC takes the negative value;and the positive anomaly center over the extratropical Pacific Ocean and the negative anomaly center over North Pacific have a stronger intensity than their counterpart centers and locate east of their counterpart center positions.
keywords:nonlinear principal component analysis(NLPCA)  artifical neural network method  EU  PNA
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