中文摘要：

首场全省性大雨天气过程对缓解云南冬春季旱情及农业生产意义重大。本文从热带季节内振荡（MJO）大气低频背景和大气环流出发,分析2016年5月21—24日云南首场全省连续性大雨天气过程发生的水汽条件和动力条件。结果表明：（1）2016年云南首场全省性连续大雨天气过程发生前后,MJO在＂湿窗口＂异常活跃;（2）MJO活动中心位于云南的＂湿窗口＂期间,孟加拉湾风暴＂罗纳＂加强且东北移动和川滇切变线南下是此次云南全省性大雨天气过程产生的主要原因;（3）孟加拉湾风暴生成后,500 h Pa副热带高压西脊点持续偏西、脊线位置持续偏南,副高外围的西南气流引导孟加拉湾风暴＂罗纳＂向东北方向移动影响云南;（4）＂罗纳＂登陆后,MJO活动中心在＂湿窗口＂,500 h Pa高度场维持低槽形势,为此次全省连续性强降水过程提供水汽输送;700 h Pa低空急流为21—22日降水过程提供动力条件,而川滇切变线南下为23日强降水天气提供动力条件。

英文摘要：

The first provincial range heavy rain process would alleviate the drought in winter and spring and help agriculture production in Yunnan Province. Based on the daily MJO index of US NOAA/CPC,NCEP/NCAR reanalysis data,precipitation at 125 weather stations in Yunnan Province,infrared cloud images of FY-2E satellite and the moving path of Bengal Bay storm,the moisture and dynamic conditions of the first provincial range heavy rain process from 21 to 24 May 2016 were analyzed by using the tropical atmospheric Madden-Julian Oscillation（MJO） and atmospheric circulation diagnosis. The results showed that MJO was extremely active in the 4th phase（the tropical area from the Bay of Bengal to the Indonesian islands） during the first provincial range heavy rain process,which adjusted Roanu＇s formation and development. After the generation of tropical storm Roanu,the western ridge point of subtropical high on 500 h Pa was more westward and the ridge line was located further south,and the storm Roanu moved to northeast and affected the weather in Yunnan Province under the influence of the southwesterly airflow outside the subtropical high. When MJO was active in the 4th phase,the low trough on 500 h Pa provided excellent vapor transport for the heavy rain process. After the storm Roanu generated over the Bay of Bengal,the low-level jet on 700 h Pa provided dynamic condition for the rainfall process from 21 to22 May 2016. The Bay of Bengal storm weakened on 23 May 2016,but MJO was still active in the 4th phase and the shear line over Sichuan and Yunnan moved to south,which caused the rainfall process on 23 May 2016.