Interdecadal variability of the ENSO teleconnection to the wintertime North Pacific
Interdecadal variability of the ENSO teleconnection to the wintertime North Pacific
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DOI：
10.1007/s00382-018-4081-y
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发表时间：
2018-02
期刊：
影响因子：
4.6
通讯作者：
C. O’Reilly
中科院分区：
文献类型：
--
作者：
C. O’Reilly
厄尔尼诺/南方涛动(ENSO)强烈影响北半球冬季热带外太平洋大尺度大气环流，对北美冬季气候有重要影响。这项研究利用一系列观测数据集和一系列大气模式模拟，分析了1900-2010年期间ENSO与冬季温带北太平洋遥相关的年代际变化。观测到的遥相关强度在20世纪发生了很大的变化。具体来说，观测发现ENSO与北太平洋环流的遥相关分别在世纪初(1912-1942年)、世纪中叶(1946-1976年)和世纪末(1980-2010年)的31年期间表现得特别强、弱和强。在大气模式集合中，ENSO与北太平洋的遥相关在本世纪中叶较弱，在本世纪末显著增强，与观测到的ENSO-北太平洋遥相关的变化密切相关。然而，在本世纪初，大气模式也表现出与北太平洋的弱遥相关，这与观测不同。在模式实现的一个子集中，表现出与本世纪初观测中类似的ENSO-北太平洋遥相关，与本世纪末相比，温带外环流有很大差异，但赤道太平洋降水异常没有差异。这表明本世纪早期的高度相关性在很大程度上是由于温带内部的变异性。讨论了这些结果对季节可预报性和季节预报系统评估的重要意义。
The El Niño/Southern Oscillation (ENSO) strongly influences the large-scale atmospheric circulation over the extratropical North Pacific during boreal winter, which has an important impact on North American winter climate. This study analyses the interdecadal variability of the ENSO teleconnection to the wintertime extratropical North Pacific, over the period 1900–2010, using a range of observationally derived datasets and an ensemble of atmospheric model simulations. The observed teleconnection strength is found to vary substantially over the 20th century. Specifically, 31-year periods in the early-century (1912–1942), mid-century (1946–1976) and the late-century (1980–2010) are identified in the observations when the ENSO teleconnection to the North Pacific circulation are found to be particularly strong, weak and strong respectively. The ENSO teleconnection to the North Pacific in the atmospheric model ensemble is weak in the mid-century period and substantially stronger in the late-century, closely following the variability in the observed ENSO-North Pacific teleconnection. In the early-century, however, the atmospheric model also exhibits a weak teleconnection to the North Pacific, unlike in observations. In a subset of the model realisations that exhibit similar ENSO-North Pacific teleconnection as in observations during the early-century period there are large differences in extratropical circulation but not in equatorial Pacific precipitation anomalies, in contrast to the late-century period. This suggests that the high correlation in the early century period is largely due to internal extratropical variability. The important implications of these results for seasonal predictability and the assessment of seasonal forecasting systems are discussed.