Abstract Studies of the Madden‐Julian Oscillation (MJO) have progressed considerably during the past decades in observations, numerical modeling, and theoretical understanding. Many theoretical attempts have been made to identify the most essential processes responsible for the existence of the MJO. Criteria are proposed to separate a hypothesis from a theory (based on the first principles with quantitative and testable assumptions, able to predict quantitatively the fundamental scales and eastward propagation of the MJO). Four MJO theories are selected to be summarized and compared in this article: the skeleton theory, moisture‐mode theory, gravity‐wave theory, and trio‐interaction theory of the MJO. These four MJO theories are distinct from each other in their key assumptions, parameterized processes, and, particularly, selection mechanisms for the zonal spatial scale, time scale, and eastward propagation of the MJO. The comparison of the four theories and more recent development in MJO dynamical approaches lead to a realization that theoretical thinking of the MJO is diverse and understanding of MJO dynamics needs to be further advanced.

中文翻译：

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马登-朱利安振荡的四种理论


摘要 过去几十年来，马登-朱利安振荡（MJO）的研究在观测、数值模拟和理论理解方面取得了长足的进步。为了确定 MJO 存在的最重要过程，人们进行了许多理论尝试。提出了将假设与理论分开的标准（基于带有定量和可测试假设的第一原理，能够定量预测 MJO 的基本尺度和向东传播）。本文选取四种MJO理论进行总结和比较：MJO的骨架理论、湿模理论、重力波理论和三重相互作用理论。这四种 MJO 理论在关键假设、参数化过程，特别是 MJO 的纬向空间尺度、时间尺度和向东传播的选择机制方面彼此不同。四种理论的比较和 MJO 动力学方法的最新发展使我们认识到 MJO 的理论思想是多种多样的，并且对 MJO 动力学的理解需要进一步推进。