Quasi‐Biennial Modulation of the Southern Ocean Coherent Mode
Quasi‐Biennial Modulation of the Southern Ocean Coherent Mode
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南大洋相干模的准两年期调制
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
V. Roussenov
中科院分区：
文献类型：
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作者：
A. Hibbert;H. Leach;P. Woodworth;C. Hughes;V. Roussenov
对1992 - 2002年期间两个独立的南大洋海平面数据集进行的经验正交函数（EOF）分析表明，连贯的海洋模态——大气南半球环状模（SAM）的纬向对称对应模态——一直作为主要的变化模态出现，并且在次年年际时间尺度上被证明是环极输送的可靠替代指标。对每个数据集的连贯模态以及一个全球正压模式的连贯模态进行交叉验证，表明海平面观测值和模式估计值之间具有高度的一致性，并且还表明在次年年际时间尺度上，连贯的海洋模态主要是由正压驱动的，而在更长的时间段内，斜压海洋效应占主导地位。连贯模态和输送都被证明受到平流层准两年振荡（QBO）的影响，并且描述了一种机制，即依赖QBO的行星波活动可能会被高纬度东风和西风急流从平流层引导至地表，引发风异常，通过向赤道的埃克曼输送迫使海平面发生变化。来自韦尔纳茨基/法拉第站更长（18年）的验潮仪记录以及一个海洋环流模式22年的海平面估计时间序列被用于表明，QBO引起的海平面和输送变化在更长的时间尺度上可能会受到太阳活动的准十年周期的调节。版权所有©2010英国皇家气象学会
Empirical Orthogonal Function (EOF) analysis of two independent Southern Ocean sea‐level datasets for the period 1992–2002 shows that the coherent oceanic mode–a zonally symmetric counterpart to the atmospheric Southern Annular Mode (SAM)–consistently emerges as the predominant mode of variability and is revealed to be a reliable proxy for circumpolar transport upon subannual to interannual time‐scales. Cross‐validation of the coherent mode from each dataset and that of a global barotropic model demonstrates a high degree of correspondence between sea‐level observations and model estimations and also indicates that the coherent oceanic mode is largely barotropically driven upon subannual time‐scales, whilst baroclinic oceanic effects predominate at longer periods. Both the coherent mode and transport are shown to be modified by the stratospheric Quasi‐Biennial Oscillation (QBO) and a mechanism is described by which QBO‐dependent planetary wave activity may be guided from the stratosphere towards the surface by high‐latitude easterly and westerly jets, inducing wind anomalies that force sea‐level variability through equatorward Ekman transport. A longer (18‐year) tide‐gauge record from the Vernadsky/Faraday station and a 22‐year time series of sea‐level estimations from an ocean general circulation model are used to show that QBO‐induced sea‐level and transport variability may be modulated upon longer time‐scales by a quasi‐decadal cycle of solar activity. Copyright © 2010 Royal Meteorological Society