This study identifies a new triggering mechanism of the Indian Ocean Dipole (IOD) from the Southern Hemisphere. This mechanism is independent from the El Niño‐Southern Oscillation (ENSO) and tends to induce the IOD before its canonical peak season. The joint effects of this mechanism and ENSO may explain different lifetimes and strengths of the IOD. During its positive phase, development of sea surface temperature cold anomalies commences in the southern Indian Ocean, accompanied by an anomalous subtropical high system and anomalous southeasterly winds. The eastward movement of these anomalies enhances the monsoon off Sumatra‐Java during May–August, leading to an early positive IOD onset. The pressure variability in the subtropical area is related with the Southern Annular Mode, suggesting a teleconnection between high‐latitude and midlatitude climate that can further affect the tropics. To include the subtropical signals may help model prediction of the IOD event.

中文翻译：

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从南半球触发印度洋偶极子

这项研究确定了南半球印度洋偶极子（IOD）的新触发机制。该机制独立于厄尔尼诺-南方涛动（ENSO），并且倾向于在其典型高峰季节之前诱发IOD。这种机制和ENSO的共同作用可能解释了IOD的不同寿命和强度。在其积极阶段，南印度洋开始出现海表温度冷异常的发展，伴随着副热带高压系统的异常和东南风的异常。这些异常的东移在5月至8月增强了苏门答腊爪哇岛的季风，导致了IOD的初期出现。亚热带地区的压力变化与南部环形模式有关，表明高纬度和中纬度气候之间存在遥相关，这可能进一步影响热带地区。包括亚热带信号可能有助于对IOD事件进行建模。