Previous observational and modeling studies indicate that the wintertime North Pacific Oscillation (NPO) could significantly impact the following winter El Niño-Southern Oscillation (ENSO) variability via the seasonal footprinting mechanism (SFM). This study explores climate projections of this winter NPO-ENSO relation in a warming climate based on a 50-member large ensemble of climate simulations conducted with the second-generation Canadian Earth System Model (CanESM2). The ensemble mean of the 50 members can well reproduce the observed winter NPO pattern, the NPO-ENSO relationship, and the SFM process over the historical period 1950–2003. These 50 members are then employed to examine climate projections of the NPO-ENSO connection over the anthropogenic forced period 2020–2073. Results indicate that there exists a large spread of projected NPO-ENSO connections across these 50 ensemble members due to internal climate variability. Internal climate variability brings uncertainties in the projection of the winter NPO-ENSO connection originally seen in projected changes of the subtropical center of the winter NPO. The spread of projections of winter NPO-associated atmospheric anomalies over the subtropical North Pacific further results in various responses in the projections of winter and spring precipitation anomalies over the tropical North Pacific, as well as spring zonal wind anomalies over the tropical western Pacific, which eventually lead to uncertainties in the projection of the sea surface temperature anomalies in the tropical central-eastern Pacific from the following summer to winter.

中文翻译：

---

气候变暖下冬季 NPO-跟随冬季 ENSO 连接的预测：由于内部气候变率导致的不确定性

先前的观测和建模研究表明，冬季北太平洋涛动 (NPO) 可能通过季节性足迹机制 (SFM) 显着影响接下来的冬季厄尔尼诺-南方涛动 (ENSO) 变化。本研究基于使用第二代加拿大地球系统模型 (CanESM2) 进行的 50 人大型气候模拟集合，探讨了在变暖气候下冬季 NPO-ENSO 关系的气候预测。50 个成员的集合平均值可以很好地再现 1950-2003 年历史时期观测到的冬季 NPO 模式、NPO-ENSO 关系和 SFM 过程。然后，这 50 名成员被用于检查 2020-2073 年人为强迫期间 NPO-ENSO 连接的气候预测。结果表明，由于内部气候变率，这 50 个集合成员之间存在大量预计的 NPO-ENSO 连接。内部气候变率给冬季 NPO-ENSO 联系的预测带来了不确定性，最初见于冬季 NPO 副热带中心的预测变化。冬季 NPO 相关大气异常预测在副热带北太平洋上的传播进一步导致热带北太平洋冬季和春季降水异常预测以及热带西太平洋春季纬向风异常预测的各种响应，最终导致热带中东部太平洋从夏季到冬季的海面温度异常预测的不确定性。