MJO对2011年秋季云南干旱期间一次强降水过程的可能影响  

Possible Impacts of the MJO on once Heavy Rain During Fall Drought of 2011 over Yunnan

作　　者：杨素雨[1] 李汀[2] 牛法宝[1] 琚建华[3] 

机构地区：[1]云南省气象台,云南昆明650034 [2]云南大学大气科学系,云南昆明650091 [3]云南省气象局,云南昆明650034

出　　处：《成都信息工程学院学报》2013年第2期175-180,共6页Journal of Chengdu University of Information Technology

基　　金：国家自然科学基金资助项目(41065004);NSFC--云南联合基金资助项目(U0833602);云南省社会发展科技计划资助项目(2009CA023);云南省气象局预报员专项资助项目(YB201202)

摘　　要：为了探讨2011年10月26~30日云南南部一次强降水过程发生的可能原因,采用诊断、合成和相关等分析方法,得到2011年10月的强热带低频振荡过程是云南南部强降水过程的一个重要影响因素。2011年10月中下旬热带低频振荡在印度洋地区异常活跃,特别是热带低频振荡对流中心在第2位相(印度洋中西部)维持了9天(20~28日),强降水过程就发生在此期间。26~30日虽没有明显冷空气配合,但热带低频振荡进入第2位相后云南上游(孟加拉湾地区)开始出现持续稳定的水汽通量和水汽通量辐合,随着南支槽的东移和副高的缓慢东移,水汽在槽前西南气流和副高外围气流的引导下源源不断向云南南部输送水汽,是南部出现强降水过程的直接原因。相关性分析和合成分析表明,热带印度洋-5°S^5°N,65°E^90°E地区的对流与云南南部降水存在显著正相关关系,当热带低频振荡对流位于第2位相(印度洋中西部),云南上游水汽条件明显改善,南部降水异常偏多。关注热带低频振荡的演变和发展,对于把握类似2011年秋季这样的强降水过程预报是有帮助的。In order to find out the possible cause of once heavy rain which happened in October 26 to 30 of 2011 over Yunnan, the relationships between the MJO（the middle-west Indian Ocean） and a heavy rain process in October of 2011 in southern Yunnan were analyzed by using the methods of diagnosis, composite and correlative analysis. Studies showed that a strong MJO process was one of the main impact factors. MJO convection was markedly active over the Indian Ocean, especially with the convection center maintaining nine days in phase 2 of MJO and just corresponding to the heavy rain process. Although cold air was weaker during October 26 to 30, the vapor flux and moisture flux convergence over upstream of Yunnan （Bengal area） were sustained and steady at a higher equilibrium when MJO convective center was active in phase 2 of MJO, and the moisture was transported continuously to the southern of Yunnan by the southwesterly flow of periphery of the subtropical high and the southern branch trough with the east- ward slowly of these two weather systems. That was the direct cause of strong precipitation in southern Yunnan. Composite and correlative analysis showed that it was remarkable positive correlation between the rain of southern Yunnan and the convection in the tropical Indian Ocean （ - 5°S- 5°N, 65°E - 90°E）. When the MJO was in phase 2, the water vapor conditions were obviously improved and the fall precipitation was more in southern Yunnan. It was potentially helpful to understand and forecast, using MJO, such kind of heavy rainfall weather anomalies as in fall 2011.

关 键 词：气象学 诊断分析 热带低频振荡 干旱 云南 强降水 印度洋 

分 类 号：P426.6[天文地球—大气科学及气象学]