近年来El Niño Modoki的提出，使得El Niño多样性成为ENSO研究领域的重点和热点问题之一。申请人前期工作首次提出两类El Niño Modoki：El Niño Modoki I和II，发现二者具有不同的海温分布和气候效应。本项目将利用多种统计分析、动力学诊断以及数值模拟实验等方法，深入探讨El Niño Modoki的爆发机制，尤其是El Niño Modoki II。主要回答以下科学问题：（1）影响El Niño Modoki I和II热带中太平洋暖海温异常形成的海洋动力学过程；（2）由副热带北太平洋西风应力异常引起的海洋上层环流影响El Niño Modoki II爆发的动力学机制；（3）造成副热带北太平洋西风应力异常变化的可能原因。本研究工作能完善El Niño Modoki的理论体系，为El Niño Modoki的预测和预报提供科学依据。

Since El Niño Modoki is discovered in recent two decades, El Niño diversity becomes one of the key and hot issues in the ENSO research field. Our previous studies classified El Niño Modoki into two groups: El Niño Modoki I and II with different origins and patterns of warm sea surface temperature (SST) anomalies, which show distinct climate impacts. The aim of proposed research is to explore the dynamics mechanisms of El Niño Modoki onset, especially El Niño Modoki II via statistical analysis, budget analysis of the thermodynamics equation in the upper mixed layer, and the model simulations. The proposed study will answer the three key questions: (1) discover the oceanic dynamics mechanisms dominating the development of the warm SST anomalies in the central tropical Pacific during El Niño Modoki I and II; (2) address the physical mechanisms of how the anomalous oceanic currents induced by the westward wind stress in the subtropical North Pacific impact the El Niño Modoki II onset; (3) explore the possible causes leading to the variations of the westward wind stress in the subtropical North Pacific. These results are helpful to develop the theoretical framework of El Niño Modoki, and provide the theoretical basis and scientific evidences for El Niño Modoki prediction and projection, which is beneficial to the scientific and social community in general.