Zonal Asymmetry of Moist Static Energy Tendency and Madden-Julian Oscillation (MJO) Eastward Propagation in Climate Models

通过过去50年改进的模式物理和初始条件，现在可以相当好地预测长达5天的天气。另一方面，由于过去20-30年对厄尔尼诺动力学的监测和了解有所改善，月度或季节性预报技能也取得了良好的进步。扩大范围(5-30天)的预测目前是最困难的。扩展范围内的主要可预报性来源是一种名为“马登-朱利安振荡(MJO)”的大气低频模式。然而，目前的操作模型很难预测这种振荡。该项目将研究目前最先进的26个气候模型中基本动力和物理过程的表示和耦合，以了解为什么这些模型中只有四分之一能够捕捉到MJO的观测时空演变特征，而其他模型则不能。这项研究结合了观测数据分析、26个气候模式输出的诊断和将关键动力/物理过程隔离的理想化数值模式试验。该项目的成功完成不仅将促进对Madden-Julian振荡动力学的认识，还将有助于发现目前最先进的业务天气预报模式中的问题，并有助于改进对大气低频振荡及其相关遥相关模式的模式表示。扩大范围预报能力的提高将为缩小短期天气预报和长期气候预报之间的差距提供一条途径，并有利于经济和社会、预防自然灾害和政府规划。该项目支持一名热带大尺度动力学和气候模型领域的研究生。

Through improved model physics and initial conditions in past 50 years, weather can now be predicted reasonably well for up to 5 days. On the other hand, due to improved monitoring and understanding of El Nino dynamics in past 20-30 years, monthly or seasonal outlook skill is also in good progress. The extended-range (5-30-day) prediction is currently most difficult. The major predictability source in extended range is an atmospheric low-frequency mode named "Madden-Julian Oscillation (MJO)". However, current operational models have difficulty to predict this oscillation. This project will investigate the representations and couplings of fundamental dynamic and physical processes in 26 current state-of-the-art climate models to gain a understanding of why only about a quarter of these models are able to capture the observed spatiotemporal evolution characteristics of MJO while others cannot. This study combines observational data analysis, diagnosis of the 26 climate model outputs, and idealized numerical model experiments in which key dynamic/physical processes are isolated.The successful completion of this project would not only advance the knowledge of dynamics of the Madden-Julian Oscillation but also help identify problems in the current state-of-the-art operational weather prediction models and help improve the model representations of the atmospheric low-frequency oscillation and its associated teleconnection patterns. The improved capability of extended-range predictions would offer an avenue for bridging the gap between the short-range weather and long-term climate predictions and benefit economy and society for prevention of natural disasters and for government planning. This project supports a graduate student in the area of tropical large-scale dynamics and climate modeling.