Pacific Meridional Modes without Equatorial Pacific Influence
Pacific Meridional Modes without Equatorial Pacific Influence
复制标题
不受赤道太平洋影响的太平洋经向模态
DOI：
10.1175/jcli-d-20-0573.1
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发表时间：
2021
影响因子：
4.9
通讯作者：
Miller, Arthur J.
中科院分区：
文献类型：
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作者：
Zhang, Yu;Yu, Shiyun;Amaya, Dillon J.;Kosaka, Yu;Larson, Sarah M.;Wang, Xudong;Yang, Jun-Chao;Stuecker, Malte F.;Xie, Shang-Ping;Miller, Arthur J.
由于太平洋经向模(PMM)的空间结构重叠，如果基于观测或完全耦合的模式模拟，在没有热带太平洋变率影响的情况下研究它们在技术上是困难的。为了解决这一问题，本研究基于一个机械解耦的气候模式模拟，研究了北PMM(NPMM)和南PMM(SPMM)的相关大气强迫和响应过程。在本实验中，规定了热带太平洋的气候学风应力，这有效地消除了热带太平洋的动力耦合变率(例如，厄尔尼诺-南方涛动)。在本实验中，年际NPMM不仅受到北太平洋涛动的强迫，而且还受到大气内部变率的北太平洋三极(NPT)模式的强迫，这主要是迫使NPMM发生年代际变化的。SPMM的年际和年代际变化部分是由南太平洋涛动强迫的。反过来，年际和年代际NPMM变率都可以通过影响全年气候热带辐合带的经向位移来激发北半球温带上空的大气遥相关。同样，年际和年代际SPMM变率也可以通过在所有季节延长或缩小气候学南太平洋辐合带来激发南半球温带上空的大气遥相关。我们的结果突出了一条新的极地路径，NPMM和SPMM都通过这种路径反馈到温带外气候，以及赤道向对热带太平洋变率的影响。
Investigating Pacific meridional modes (PMMs) without the influence of tropical Pacific variability is technically difficult if based on observations or fully coupled model simulations due to their overlapping spatial structures. To confront this issue, the present study investigates both the North PMM (NPMM) and South PMM (SPMM) in terms of their associated atmospheric forcing and response processes based on a mechanically decoupled climate model simulation. In this experiment, the climatological wind stress is prescribed over the tropical Pacific, which effectively removes dynamically coupled tropical Pacific variability (e.g., El Niño–Southern Oscillation). Interannual NPMM in this experiment is forced not only by the North Pacific Oscillation but also by a North Pacific tripole (NPT) pattern of atmospheric internal variability, which primarily forces decadal NPMM variability. Interannual and decadal variability of the SPMM is partly forced by the South Pacific Oscillation. In turn, both interannual and decadal NPMM variability can excite atmospheric teleconnections over the Northern Hemisphere extratropics by influencing the meridional displacement of the climatological intertropical convergence zone throughout the whole year. Similarly, both interannual and decadal SPMM variability can also excite atmospheric teleconnections over the Southern Hemisphere extratropics by extending or shrinking the climatological South Pacific convergence zone in all seasons. Our results highlight a new poleward pathway by which both the NPMM and SPMM feed back to the extratropical climate, in addition to the equatorward influence on tropical Pacific variability.