中国东部冬季的强冷空气活动和与之伴随的大范围低温雨雪往往会造成严重的危害。虽然已有许多研究分析了中国东部冷空气活动发生的过程和影响因子，但较少有研究关注不同尺度变化对中国东部冬季大范围冷事件发生的不同作用和热带低频振荡的可能影响。本项目将结合资料分析和动力诊断，揭示中纬度天气尺度和季节内尺度过程对中国东部冬季大范围强冷事件发生的相对贡献和季节内尺度过程对长时间持续的冷事件的维持作用。本项目将通过统计分析，研究中国东部冬季的冷空气活动与热带低频振荡的关系，并将进行诊断分析，揭示热带MJO影响中国东部冬季冷空气活动的物理过程。本研究将系统分析MJO和中高纬度季节内尺度变动在中国东部冬季冷空气活动中的单独作用和协同作用，从而认识和理解低纬度过程和中高纬度大气环流对中国东部大范围低温发生的综合影响。本项目的开展将对增强中国东部冬季强冷空气活动机理的认识和提高冷空气事件发生的预测水平有重要的意义。

Eastern China is often subjected to serious impacts by large-scale low temperature, rain and snow induced by strong cold events during boreal winter. While many studies have been conducted to investigate the processes and factors of the occurrence of cold events over eastern China, very few have been devoted to the roles of different time scale variations in the large-scale cold events over eastern China during boreal winter and the plausible impacts of tropical low-frequency oscillations. This project will conduct data analyses and dynamic diagnoses to unravel the relative contributions of mid-latitude synoptic and intraseasonal time scale variations to the large-scale strong cold events and the roles of intraseasonal time scales in sustaining the long duration cold events over eastern China during boreal winter. This study will attempt to identify the relation of eastern China cold event activity to the tropical intraseasonal oscillation through statistical analyses and to understand the specific physical processes of the MJO’s influence on the occurrence of the cold events through diagnoses. Furthermore, this project will analyze the individual and coherent roles of the MJO and mid-latitude intraseasonal oscillations in the cold air activity over eastern China to understand the combined effects of low-latitude and mid-latitude processes in the large-scale low temperature events. Accomplishment of this project will advance our understanding of mechanisms of occurrence of strong cold events and help to improve the skill of prediction of the cold events over eastern China.