In this study, the impacts of the tropical Pacific-Indian Ocean associated mode (PIOAM) on Madden-Julian Oscillation (MJO) activity were investigated using reanalysis data. In the positive (negative) phase of the PIOAM, the amplitudes of MJO zonal wind and outgoing longwave radiation are significantly weakened (enhanced) over the Indian Ocean, while they are enhanced (weakened) over the central and eastern Pacific. The eastward propagation of the MJO can extend to the central Pacific in the positive phase of the PIOAM, whereas it is mainly confined to west of 160°E in the negative phase. The PIOAM impacts MJO activity by modifying the atmospheric circulation and moisture budget. Anomalous ascending (descending) motion and positive (negative) moisture anomalies occur over the western Indian Ocean and central-eastern Pacific (Maritime Continent and western Pacific) during the positive phase of the PIOAM. The anomalous circulation is almost the opposite in the negative phases of the PIOAM. This anomalous circulation and moisture can modulate the activity of the MJO. The stronger moistening over the Indian Ocean induced by zonal and vertical moisture advection leads to the stronger MJO activity over the Indian Ocean in the negative phase of the PIOAM. During the positive phase of the PIOAM, the MJO propagates farther east over the central Pacific owing to the stronger moistening there, which is mainly attributable to the meridional and vertical moisture advection, especially low-frequency background state moisture advection by the MJO’s meridional and vertical velocities.

中文翻译：

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热带太平洋-印度洋相关模式对马登-朱利安振荡活动的调制

在这项研究中，使用再分析数据研究了热带太平洋-印度洋相关模式 (PIOAM) 对马登-朱利安涛动 (MJO) 活动的影响。在 PIOAM 的正（负）相位，MJO 纬向风和出射长波辐射的振幅在印度洋上显着减弱（增强），而在中太平洋和东太平洋增强（减弱）。MJO的向东传播在PIOAM的正相位时可以延伸到中太平洋，而在负相位时主要限制在160°E以西。PIOAM 通过修改大气环流和水分收支来影响 MJO 活动。在 PIOAM 的正相位期间，异常上升（下降）运动和正（负）水分异常发生在西印度洋和中东部太平洋（海洋大陆和西太平洋）。异常环流在 PIOAM 的负相中几乎相反。这种异常循环和水分可以调节 MJO 的活动。纬向和垂直水分平流引起的印度洋上空的较强润湿导致印度洋上空 PIOAM 负相的 MJO 活动较强。在 PIOAM 的正相位期间，MJO 向东传播到中太平洋，因为那里的湿润更强，这主要归因于经向和垂直水分平流，