MJO Teleconnections over the PNA Region in Climate Models. Part I: Performance- and Process-Based Skill Metrics
MJO Teleconnections over the PNA Region in Climate Models. Part I: Performance- and Process-Based Skill Metrics
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DOI：
10.1175/jcli-d-19-0253.1
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发表时间：
2020-01
影响因子：
4.9
通讯作者：
Jiabao Wang;Hyemi Kim;Daehyun Kim;S. A. Henderson;C. Stan;E. Maloney
中科院分区：
文献类型：
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作者：
Jiabao Wang;Hyemi Kim;Daehyun Kim;S. A. Henderson;C. Stan;E. Maloney
我们提出了一套MJO遥相关诊断，使模型模拟的客观评价，一个公平的模型到模型的比较，并一致跟踪模型的改进。各种技能指标来自遥相关诊断，包括五个性能为基础的指标，其特征在于模式，幅度，东西位置，持久性和一致性的MJO遥相关和额外的两个面向过程的指标，旨在表征异常Rossby波源（RWS）的位置和强度。利用提出的遥相关技术指标对29个全球气候模式（GCMs）中北半球冬季MJO遥相关（500 hPa高度距平）特征进行了比较。结果表明，目前的GCM一般产生的MJO遥相关，更强，更持久，并延伸到太远的东方相比，在再分析中观察到的。在一般情况下，模式模拟更现实的遥相关模式时，MJO是在阶段2-3或阶段7-8，其特征是在印度洋和太平洋西部到中部的偶极子对流模式。阶段2、7和8的模型技巧较高，可能是由于这些阶段在个别MJO事件之间产生比其他阶段更一致的遥相关模式，尽管大多数模型的一致性低于观察到的。模拟真实RWS模式的模型可以更好地再现MJO遥相关模式。
We propose a set of MJO teleconnection diagnostics that enables an objective evaluation of model simulations, a fair model-to-model comparison, and a consistent tracking of model improvement. Various skill metrics are derived from teleconnection diagnostics including five performance-based metrics that characterize the pattern, amplitude, east–west position, persistence, and consistency of MJO teleconnections and additional two process-oriented metrics that are designed to characterize the location and intensity of the anomalous Rossby wave source (RWS). The proposed teleconnection skill metrics are used to compare the characteristics of boreal winter MJO teleconnections (500-hPa geopotential height anomaly) over the Pacific–North America (PNA) region in 29 global climate models (GCMs). The results show that current GCMs generally produce MJO teleconnections that are stronger, more persistent, and extend too far to the east when compared to those observed in reanalysis. In general, models simulate more realistic teleconnection patterns when the MJO is in phases 2–3 or phases 7–8, which are characterized by a dipole convection pattern over the Indian Ocean and western to central Pacific. The higher model skill for phases 2, 7, and 8 may be due to these phases producing more consistent teleconnection patterns between individual MJO events than other phases, although the consistency is lower in most models than observed. Models that simulate realistic RWS patterns better reproduce MJO teleconnection patterns.