The Antarctic circumpolar wave and its seasonality: Intrinsic travelling modes and El Niño–Southern Oscillation teleconnections
The Antarctic circumpolar wave and its seasonality: Intrinsic travelling modes and El Niño–Southern Oscillation teleconnections
复制标题
南极绕极波及其季节性：固有旅行模式和厄尔尼诺-南方涛动遥相关
DOI：
--
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
J. Slawinska
中科院分区：
文献类型：
--
作者：
Xinyang Wang;D. Giannakis;J. Slawinska
利用非线性拉普拉斯谱分析（NLSA）研究了南大洋的年际变化。非线性拉普拉斯谱分析是一种非线性动力系统的客观特征分解技术，可以同时从数据中高技能地恢复多个时间尺度。应用模拟和观测的海面温度和海冰浓度数据，NLSA恢复了与南极环极波（ACW）对应的波数‐2向东传播的信号。在其生命周期的某些阶段，这种模式的空间模式显示出一种结构，可以解释南极偶极子模式的统计起源。另一组模态的组合频率与ACW对年周期的调制一致。对这些新发现的模式的进一步研究表明，它们既可以向东传播，也可以向西传播，并结合让人想起海冰重新出现模式的经向脉动。此外，它们表现出更小尺度的空间结构，并比主要的ACW模态解释了更多的印度洋变异。我们将这些模态归因于ACW与热带印度洋-太平洋之间的遥相关；特别是El Niño-Southern涛动（ENSO）基本模态及其与NLSA反演的年周期相关联的组合模态。从南极变量提取的另一个模态显示南大洋上向东传播的波数- 3结构，但与印度洋-太平洋年际变率没有显著相关性。
Interannual variability in the Southern Ocean is investigated via nonlinear Laplacian spectral analysis (NLSA), an objective eigendecomposition technique for nonlinear dynamical systems that can simultaneously recover multiple timescales from data with high skill. Applied to modelled and observed sea surface temperature and sea ice concentration data, NLSA recovers the wavenumber‐2 eastwards propagating signal corresponding to the Antarctic circumpolar wave (ACW). During certain phases of its lifecycle, the spatial patterns of this mode display a structure that can explain the statistical origin of the Antarctic dipole pattern. Another group of modes have combination frequencies consistent with the modulation of the annual cycle by the ACW. Further examination of these newly identified modes reveals that they can have either eastwards or westwards propagation, combined with meridional pulsation reminiscent of sea ice reemergence patterns. Moreover, they exhibit smaller‐scale spatial structures and explain more Indian Ocean variance than the primary ACW modes. We attribute these modes to teleconnections between ACW and the tropical Indo‐Pacific Ocean; in particular, fundamental El Niño–Southern Oscillation (ENSO) modes and their associated combination modes with the annual cycle recovered by NLSA. Another mode extracted from the Antarctic variables displays an eastwards propagating wavenumber‐3 structure over the Southern Ocean, but exhibits no significant correlation to interannual Indo‐Pacific variability.