DYNAMO国际观测计划期间MJO对流触发的动力机理分析及多模式比较

季节内振荡（MJO）为热带大气季节内尺度变化最主要的模态，其对热带的天气和气候变化具有显著影响，了解MJO的触发机制是提高延伸期预报能力的关键。本项目拟利用国际大型观测计划DYNAMO/CINDY2011的数据和新一代高分辨率再分析资料，结合数值试验，对季节内振荡的触发机制进行研究。主要包含三个目标：1）分析西印度洋MJO触发前的动力和热力信号，尤其是高频天气尺度扰动在MJO触发过程中所起的作用。2）发展模式评估的综合指标，系统评估国际上主要业务预报模式在DYNAMO/CINDY2011期间回报试验中对MJO模拟的能力，了解模式模拟偏差的可能来源。3）开展敏感性数值试验，揭示前期动力和热力信号、遥强迫和局地过程、高频和低频扰动等对MJO触发的相对贡献。

The Intraseasonal Oscillation (ISO; aka Madden-Julian Oscillation (MJO)) is the most prominent mode of intraseasonal variability in the tropics. As it exerts great influences upon the weather and climate systems in tropics, understanding its initiation mechanism is the key to increasing the capability of extended-range weather forecasting. This proposal aims to use both the multi-agencies sponsored DYNAMO/CINDY2011 field campaign data plus new-generation high-resolution reanalysis data, and conduct numerical experiments to investigate the initiation mechanisms of MJO. This proposal consists of three major tasks. 1）we propose to analyze the precursor dynamic and thermodynamic processes prior to MJO initiation in the western Indian Ocean, with a special focus on the role of high-frequency eddies in MJO initiation during the DYNAMO campaign period. 2）we will develop intercomparison metrics to systematically evaluate operational and research model performance in hindcasts of the MJO events during the campaign period and to identify the source of model errors. 3）we will examine at what lead time the models are able to predict each of individual MJO events. Our strategy is to diagnose observed dynamic and thermodynamic precursor signals and examine how well the models capture these precursor signals. A special attention will be paid to low-level moistening and extratropical perturbations that trigger MJO convection. For models that captured the observed moistening and triggering processes, we will further conduct sensitivity experiments to investigate the relative importance of each processes in triggering the MJOs.