Possible roles of large-scale precipitation on model simulations of the Madden-Julian Oscillation (MJO) were investigated using the Large-scale Precipitation Tracking (LPT) method. Individual LPT systems and eastward propagating MJO LPT systems were identified in both observations and 25 general circulation model (GCM) simulations. LPT systems show dominant eastward propagation over the Indian Ocean in the observation, whereas LPT systems are too stationary in GCM simulations. The MJO statistical signals in the model simulations are represented by the occurence frequencies of LPT systems with a size of ∼4–9 × 10⁶ km² (∼20–30° in longitude and latitude) and a strength of ∼15–18 mm d⁻¹. Growth rate in size of LPT systems in early stage determines the size of LPT systems, which differentiates the MJO statistical signals among the GCM simulations. Comprehensive diagnostics of MJO simulations in GCMs should include both individual LPT systems as essential elements and the MJO statistical signals.

中文翻译：

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大规模降水系统：马登-朱利安振荡的基本要素

使用大规模降水跟踪 (LPT) 方法研究了大规模降水对麦登-朱利安振荡 (MJO) 模型模拟的可能作用。在观测和 25 个大环流模型 (GCM) 模拟中，确定了单个 LPT 系统和向东传播的 MJO LPT 系统。LPT 系统在观测中显示出在印度洋上空的主要向东传播，而 LPT 系统在 GCM 模拟中过于稳定。模型模拟中的 MJO 统计信号由 LPT 系统的出现频率表示，大小约为 4–9 × 10 ⁶  km ²（经纬度约为 20–30°），强度约为 15–18 mm d ^-1. 早期 LPT 系统规模的增长速度决定了 LPT 系统的规模，从而区分 GCM 模拟中的 MJO 统计信号。GCM 中 MJO 模拟的综合诊断应包括作为基本要素的单个 LPT 系统和 MJO 统计信号。