The Pacific Decadal Oscillation (PDO), the leading mode of Pacific decadal sea surface temperature variability, arises mainly from combinations of regional air-sea interaction within the North Pacific Ocean and remote forcing, such as from the tropical Pacific and the Atlantic. Because of such a combination of mechanisms, a question remains as to how much PDO variability originates from these regions. To better understand PDO variability, the equatorial Pacific and the Atlantic impacts on the PDO are examined using several 3-dimensional partial ocean data assimilation experiments conducted with two global climate models: the CESM1.0 and MIROC3.2m. In these partial assimilation experiments, the climate models are constrained by observed temperature and salinity anomalies, one solely in the Atlantic basin and the other solely in the equatorial Pacific basin, but are allowed to evolve freely in other regions. These experiments demonstrate that, in addition to the tropical Pacific’s role in driving PDO variability, the Atlantic can affect PDO variability by modulating the tropical Pacific climate through two proposed processes. One is the equatorial pathway, in which tropical Atlantic sea surface temperature (SST) variability causes an El Niño-like SST response in the equatorial Pacific through the reorganization of the global Walker circulation. The other is the north tropical pathway, where low-frequency SST variability associated with the Atlantic Multidecadal Oscillation induces a Matsuno-Gill type atmospheric response in the tropical Atlantic-Pacific sectors north of the equator. These results provide a quantitative assessment suggesting that 12–29% of PDO variance originates from the Atlantic Ocean and 40–44% from the tropical Pacific. The remaining 27–48% of the variance is inferred to arise from other processes such as regional ocean-atmosphere interactions in the North Pacific and possibly teleconnections from the Indian Ocean.

太平洋年代际振荡（PDO）是太平洋年代际海面温度变化的主要模式，主要来自北太平洋内部的区域海-气相互作用和来自热带太平洋和大西洋的偏远强迫作用。由于机制的这种组合，对于这些区域产生多少PDO变异性仍然存在疑问。为了更好地了解PDO的变化性，使用了两个全球气候模型（CESM1.0和MIROC3.2m）进行的几个3维部分海洋数据同化实验，研究了赤道​​太平洋和大西洋对PDO的影响。在这些部分同化实验中，气候模型受到观测到的温度和盐度异常的约束，一个单独在大西洋盆地，另一个单独在赤道太平洋盆地，但被允许在其他地区自由演化。这些实验表明，除了热带太平洋在驱动PDO变异中的作用外，大西洋还可以通过两个拟议的过程来调节热带太平洋的气候，从而影响PDO的变异性。一种是赤道途径，其中热带大西洋海表温度（SST）的变化通过重组全球Walker环流在赤道太平洋中引起类似ElNiño的SST响应。另一个是北部热带路径，其中与大西洋多年代际涛动相关的低频海表温度变化会诱发赤道以北热带大西洋-太平洋地区的松野-吉尔型大气响应。这些结果提供了定量评估，表明PDO变化的12–29％来自大西洋，而40–44％来自热带太平洋。其余27％至48％的变化是由其他过程引起的，例如北太平洋的区域海洋与大气相互作用以及印度洋的遥相关。