This study investigates how the El Niño-Southern Oscillation (ENSO) modulates the intraseasonal variability (ISV) of Pacific-Japan (PJ) teleconnection pattern. The PJ index during boreal summer is constructed from the empirical orthogonal function (EOF) of the 850-hPa zonal wind (U850) anomalies. Distinct periods of the PJ index are found during El Niño and La Niña summers. Although ISV of the PJ pattern is significant during 10-25 days for both types of summers, it peaks on Days 30 and 60 in El Niño and La Niña summers respectively. During El Niño summers, the 30-day ISV of PJ pattern is related to the northwestward propagating intraseasonal oscillation (ISO) over the western North Pacific (WNP), which is originated from the tropical Indian Ocean (IO). During La Niña summers, the 60-day ISV of PJ pattern is related to the northeastward propagating ISO from the tropical IO. The low-frequency ISV modes in both El Niño and La Niña summers are closely related to the boreal summer ISO (BSISO), and the high-frequency ISV modes over WNP are related to the quasi-biweekly oscillation. The underlying mechanisms for these different evolutions are also discussed.

中文翻译：

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ENSO对日本太平洋模式季节内变化的调节

这项研究调查了厄尔尼诺-南方涛动（ENSO）如何调节日本太平洋（PJ）遥距模式的季节内变化（ISV）。北方夏季的PJ指数是根据850-hPa纬向风（U850）异常的经验正交函数（EOF）构造的。在厄尔尼诺和拉尼娜夏季发现PJ指数的不同时期。尽管两种类型的夏季PJ模式的ISV均很显着，但在厄尔尼诺和拉尼娜夏季分别在第30天和第60天达到峰值。在厄尔尼诺夏季，PJ模式的30天ISV与起源于热带印度洋（IO）的北太平洋西部（WNP）向西北传播的季节内振荡（ISO）有关。在拉尼娜（LaNiña）夏季，PJ模式的60天ISV与热带IO向东北传播的ISO有关。厄尔尼诺和拉尼娜夏季的低频ISV模式与北方夏季ISO（BSISO）密切相关，而WNP上的高频ISV模式与准双周振荡有关。还讨论了这些不同演变的潜在机制。