Using wind reanalysis dataset, we propose a definition for easterly wind bursts (EWBs) occurring in the Indian Ocean and analyze their effects on positive Indian Ocean Dipole (pIOD) events. It was found that there were eight pIOD events during the period from 1980–2020, all of which were accompanied by EWBs occurrence in spring except 2015. The significant impact of EWBs on pIOD events is through the Bjerkness feedback process, strengthening upwelling in the Eastern Indian Ocean (EIO) and triggering a westward zonal current in the equatorial Indian Ocean, both cooling the EIO and in turn strengthening the easterly wind anomalies. Further analysis reveals that the negative upper ocean heat content (OHC) anomalies in EIO, acting as a trigger of Bjerkness feedback process, also plays a critical role in the development of pIOD. Thus, the simultaneous occurrence of EWBs and negative OHC anomalies in spring is an important precursor to pIOD occurrence, although there are possible other triggers.

中文翻译：

---

印度洋春季东风爆发的定义及其在触发 IOD 正事件中的作用

使用风再分析数据集，我们提出了印度洋发生的东风爆发（EWB）的定义，并分析了它们对印度洋偶极子（pIOD）正事件的影响。结果发现，1980-2020年期间共发生了8次pIOD事件，除2015年外，所有这些事件都伴随着春季EWBs的发生。EWBs对pIOD事件的显着影响是通过Bjerkness反馈过程，加强了东部地区的上升流。印度洋（EIO）并在赤道印度洋引发西向纬流，既冷却了EIO，又增强了东风异常。进一步分析表明，EIO中的上层海洋热含量（OHC）负异常，作为Bjerkness反馈过程的触发因素，在pIOD的发展中也发挥着关键作用。因此，春季同时发生 EWB 和 OHC 负异常是 pIOD 发生的重要前兆，尽管可能还有其他触发因素。