冬季北太平洋NPGO模态和NPO模态的耦合特征分析
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摘要
利用EOF分解和SVD分解方法,揭示了冬季北太平洋的海平面气压和海表面温度的主要模态,并利用统计方法对第二耦合模态的耦合特征进行了解释。结果表明,SLPA和SSTA的第二模态为NPO模态和NPGO模态,第二耦合模态的空间结构反映了中纬度北太平洋中西部是两者相互作用的关键区域;时间变化趋势表明北太平洋大气和海洋的第二耦合模态正在由高频变化转换为低频变化,且SLPA上表现出的气候迁移要早于SSTA;NPGO模态与海表西风EOF分解的第二模态密切相关,这反映了NPO模态通过海表面西风异常影响着NPGO模态的结构。
In this paper, the EOF and SVD method was used for surface level pressure anomalies(SLPA) and sea surface temperature anomalies(SSTA) in the North Pacific ocean in winter, and their coupling feature was discussed by both the statistical analysis and the numerical model. The second SVD modes of SLPA and SSTA reflect the NPO mode and NPGO mode, separately. The spatial structure shows that the main interaction occurred at the mid-latitudinal western area. Time series variation trend indicates that the second modes of atmosphere and ocean in the North Pacific are changing from high frequency to low, and the climate shift appeared in SLPA is earlier than that of SSTA. The second EOF mode of latitudinal wind anomalies reveals that the NPO mode can influence the NPGO mode through the near-surface westerly wind. When the NPGO is at positive phase, the spatial feature of SLPA is similar to NPO mode, and the westerly anomalies is proportion to longitudinal gradient,which can testify the close relation between NPO mode and NPGO mode. At the same time, sensitivity experiments of oceanic model show that the influence of latitudinal wind stress to NPGO mode is most obvious.
In this paper, the EOF and SVD method was used for surface level pressure anomalies(SLPA) and sea surface temperature anomalies(SSTA) in the North Pacific ocean in winter, and their coupling feature was discussed by both the statistical analysis and the numerical model. The second SVD modes of SLPA and SSTA reflect the NPO mode and NPGO mode, separately. The spatial structure shows that the main interaction occurred at the mid-latitudinal western area. Time series variation trend indicates that the second modes of atmosphere and ocean in the North Pacific are changing from high frequency to low, and the climate shift appeared in SLPA is earlier than that of SSTA. The second EOF mode of latitudinal wind anomalies reveals that the NPO mode can influence the NPGO mode through the near-surface westerly wind. When the NPGO is at positive phase, the spatial feature of SLPA is similar to NPO mode, and the westerly anomalies is proportion to longitudinal gradient,which can testify the close relation between NPO mode and NPGO mode. At the same time, sensitivity experiments of oceanic model show that the influence of latitudinal wind stress to NPGO mode is most obvious.
引文
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[17]吕庆平.冬季北太平洋环流振荡之研究[D].南京:解放军理工大学气象学院,2013.
[2]刘秦玉,李春,胡瑞金.北太平洋的年代际振荡与全球变暖[J].气候与环境研究,2010,15(2):217-224.
[3]Zhang Y,Norris J R,Wallace J M.Seasonality of Large-Scale Atmosphere-Ocean Interaction over the North Pacific[J].Journal of Climate,1998,11:2473-2481.
[4]朱益民,杨修群,俞永强,等.FGOAIS-g快速耦合模式模拟的北太平洋年代际变率[J].地球物理学报,2008,51(1):58-69.
[5]杨修群,朱益民,谢倩,等.太平洋年代际振荡的研究进展[J].大气科学,2004,28(6):979-992.
[6]Di Lorenzo E,Schneider N,Cobb K M,et al.North Pacific Gyre Oscillation Links Ocean Climate and Ecosystem Change[J].Geophysical Research Letters,2008,35(8):L08607.
[7]Bond N A,Overland J E,Spillane M,et al.Recent Shifts in the state of the North Pacific[J].Geophysical Research Letters,2003,30(23):2183.
[8]Walker G T,Bliss E W.World Weather V[J].Memoirs of the Royal Meteorological Society,1932,4(36):53-84.
[9]Ceballos L,Di Lorenzo E,Hoyos C D.North Pacific Gyre Oscillation Synchronizes Climate Fluctuations in the Eastern and Western Boundary Systems[J].Journal of Climate,2009,22(19):5163-5174.
[10]Qiu B,Chen S M.Eddy-Mean Flow Interaction in the Decadally Modulating Kuroshio Extension System[J].Deep-Sea ResearchⅡ:Topical Studies in Oceanography,2010,57(13-14):1098-1110.
[11]Chhak K C,Di Lorenzo E,Schneider N,et al.Forcing of LowFrequency Ocean Variability in the Northeast Pacific[J].Journal of Climate,2009,22(5):1255-1276.
[12]Furtado J C,Di Lorenzo E,Schneider N,et al.North Pacific Decadal Variability and Climate Change in the IPCC AR4 Models[J].Journal of Climate,2011,24(12):3049-3067.
[13]魏凤英.现代气候统计诊断与预测技术(第2版)[M].北京:气象出版社,2007:160-169.
[14]North G R,Bell T L,Cahalan R,et al.Sampling Errors in the Estimation of Empirical Orthogonal Functions[J].Monthly Weather Review,1982,110(7):699-706.
[15]张永垂,张立凤.冬季黑潮海域异常加热与北太平洋大气环流的耦合关系[J].热带气象学报,2009,25(6):740-746.
[16]Yeh S W,Kang Y J,Noh Y,et al.The North Pacific Climate Transitions of the Winters of 1976/77 and 1988/89[J].Journal of Climate,2011,24(4):1170-1183.
[17]吕庆平.冬季北太平洋环流振荡之研究[D].南京:解放军理工大学气象学院,2013.