Interactions between Kuroshio Extension and Central Tropical Pacific lead to preferred decadal-timescale oscillations in Pacific climate
Interactions between Kuroshio Extension and Central Tropical Pacific lead to preferred decadal-timescale oscillations in Pacific climate
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DOI：
10.1038/s41598-019-49927-y
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发表时间：
2019-09-19
影响因子：
4.6
通讯作者：
Di Lorenzo, Emanuele
中科院分区：
文献类型：
--
作者：
Joh, Youngji;Di Lorenzo, Emanuele
黑潮延伸体（KE）具有显著的年代际波动，增强了北太平洋气候的低频变率。利用现有的观测资料，我们表明，一个首选的年代际时间尺度在KE出现KE和热带太平洋中部之间的相互作用，通过经向模式。具体而言，我们表明，KE状态的变化应用持久的下游大气响应（例如风应力旋度，0-12个月的时间尺度），该项目上的大气强迫太平洋经向模态（PMM）超过9个月的时间尺度。随后，PMM激发了热带太平洋中部厄尔尼诺南方涛动（CP-ENSO）及其大气遥相关回到北方半球（1-3个月的时间尺度），这反过来又激发了北太平洋中部/东部的海洋Rossby波，向西传播，改变了KE（类似于3年的时间尺度）。与这一假设相一致，KE和PMM/CP-ENSO指数之间的互相关函数表现出显着的正弦形状对应于一个首选的光谱功率在十年的时间尺度（类似于10年）。这条动力学路径（KE -> PMM/CP-ENSO -> KE）可能为解释北太平洋的年代际时间尺度优势和增强太平洋气候的年代际可预报性提供了新的机制依据。
The Kuroshio Extension (KE) exhibits prominent decadal fluctuations that enhance the low-frequency variability of North Pacific climate. Using available observations, we show evidence that a preferred decadal timescale in the KE emerges from the interaction between KE and the central tropical Pacific via Meridional Modes. Specifically, we show that changes in the KE states apply a persistent downstream atmospheric response (e.g. wind stress curl, 0-12 months timescales) that projects on the atmospheric forcing of the Pacific Meridional Modes (PMM) over 9 months timescales. Subsequently, the PMM energizes the central tropical Pacific El Nirio Southern Oscillation (CP-ENSO) and its atmospheric teleconnections back to the Northern Hemisphere (1-3 months timescale), which in turn excites oceanic Rossby waves in the central/eastern North Pacific that propagate westward changing the KE (similar to 3 years timescales). Consistent with this hypothesis, the cross-correlation function between the KE and the PMM/CP-ENSO indices exhibits a significant sinusoidal shape corresponding to a preferred spectral power at decadal timescales (similar to 10 years). This dynamics pathway (KE -> PMM/CP-ENSO -> KE) may provide a new mechanistic basis to explain the preferred decadal-timescale of the North Pacific and enhance decadal predictability of Pacific climate.