The complex network approach has proved to be a valuable tool for climate and atmospheric sciences in recent years. Here, we show an application of causality ideas in complex networks to infer properties of equatorial wave interactions associated with the Madden–Julian Oscillation (MJO), the dominant component of the atmospheric system on intraseasonal timescales in the equatorial region. We use the normal mode function approach to obtain the time series of baroclinic Kelvin and Rossby mode energies, since both of these wave modes are known to play an important role in the MJO dynamics. The partial directed coherence method reveals the structure of the interaction among those modes and shows that the Kelvin mode is the main driver of the MJO system, transferring energy to the Rossby modes. Investigation on the Kelvin mode information source might help evaluating the state-of-the-art of MJO theories.

近年来，复杂网络方法已被证明是气候和大气科学的宝贵工具。在这里，我们展示了因果关系思想在复杂网络中的应用，以推断与麦登-朱利安振荡 (MJO) 相关的赤道波相互作用的特性，麦登-朱利安振荡 (MJO) 是赤道地区季节内时间尺度上大气系统的主要组成部分。我们使用正常模式函数方法来获得斜压开尔文和罗斯比模式能量的时间序列，因为已知这两种波模式在 MJO 动力学中都起着重要作用。部分定向相干方法揭示了这些模式之间相互作用的结构，并表明开尔文模式是 MJO 系统的主要驱动力，将能量转移到罗斯比模式。