Why Pacific quasi-decadal oscillation has emerged since the mid-20th century
Why Pacific quasi-decadal oscillation has emerged since the mid-20th century
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DOI：
10.1088/1748-9326/aca782
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发表时间：
2022-12-01
影响因子：
6.7
通讯作者：
Liu, Jian
中科院分区：
文献类型：
--
作者：
Jin, Chunhan;Wang, Bin;Liu, Jian
太平洋准年代际振荡（PQDO）是热带太平洋多时间尺度年代际变率的一个分量，其变率中心位于赤道中太平洋（ECP）。PQDO自20世纪50年代以来出现，对亚洲、北美和太平洋风暴的年代际气候变率有重要影响。然而，自20世纪50年代以来，它为何加剧仍不得而知。本文通过对群落地球系统模式-最后千年集成模式项目的1个固定强迫控制（CTRL）实验和4个千禧年光谱太阳辐照度（SSI）敏感实验的模拟结果进行分析，验证了两个相互竞争的假设，即(1)11年太阳周期强迫和(2)厄尔尼诺-南方涛动（ENSO）不对称引起的内部变率。四元整体平均SSI实验表明，如果没有平流层太阳强迫的放大，11年的太阳辐照强迫不能激发PQDO。通过144年的观测和CTRL实验分析，我们发现PQDO是非平稳的，连续的La nina引起的年代际变率可以促进ECP的PQDO。厄尔尼诺现象在NINO3.4区域可诱发ENSO的年代际变化，而在PQDO区域则不能。PQDO负相倾向于跟随多年拉尼娜的发生。我们认为，20世纪50年代以来PQDO的出现主要是由于多年拉尼娜事件的增加。
Pacific quasi-decadal oscillation (PQDO) is one component of the multi-time-scale tropical Pacific decadal variability, with a variability center in the equatorial central Pacific (ECP). PQDO has emerged since the 1950s and has a significant impact on decadal climate variability over Asia and North America and Pacific storms. However, why it has intensified since the 1950s remains unknown. Here we test two competing hypotheses, (1) 11-year solar cycle forcing and (2) internal variability arising from El Nino-Southern Oscillation (ENSO) asymmetry, by analyzing simulation results, including one fixed-forcing control (CTRL) experiment and four sensitive experiments with millennial spectral solar irradiance (SSI), obtained from the Community Earth System Model-Last Millennium Ensemble modeling project. The four-member ensemble-averaged SSI experiments suggest that 11-year solar irradiance forcing cannot excite PQDO without stratospheric amplification of solar forcing. By analyzing 144 years of observations and the CTRL experiment, we find that the PQDO is nonstationary, and consecutive La Nina-induced decadal variability can boost PQDO in the ECP. El Nino could induce decadal ENSO signals in the NINO3.4 region but not in PQDO regions. The negative phase of PQDO tends to follow the occurrence of multi-year La Nina. We suggest that the emergence of PQDO since the 1950s is mainly due to the increase in multi-year La Nina events.