平流层强、弱极涡事件的演变过程及其对我国冬季天气的影响  

Variabilities of the Stratospheric Polar Vortex and the Influence on the Weather of China during the Boreal Winter

作　　者：魏麟骁[1,2] 陈权亮[2] 程炳岩[1] 刘晓冉[1] 

机构地区：[1]重庆市气候中心,重庆401147 [2]成都信息工程学院大气科学学院,高原大气与环境四川省重点实验室,成都610225

出　　处：《大气科学》2014年第3期551-562,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目41005021;成都信息工程学院科研人才基金项目J201112;重庆市科委之自然基金“三峡库区极端气候事件预估研究”项目

摘　　要：本文利用1979-2010年的NCEP再分析资料，通过北半球环状模NAM指数挑选出的强、弱极涡个例，分析了北半球平流层异常变化过程中行星波的演变以及与之相联系的我国天气的变化特征。结果表明，在强极涡事件前，行星波1波会被反射回对流层，极地波导减弱，低纬波导增强，中高纬地区的E—P通量矢量有着从平流层传播到对流层的趋势；强极涡事件后，极地波导增强，低纬波导减弱。在弱极涡事件前，中、高纬度行星波1波沿着极地波导的传播明显增强；弱极涡事件后，极地波导明显减弱。与此对应的我国天气也有明显变化，在强极涡事件前，我国大部分地区温度偏低，南方地区偏湿而新疆西北部和云南西部地区偏干；在强极涡事件后，东亚冬季风进一步增强，冷空气加强南下，南方地区可降水量减少，新疆西北部仍然偏干，而云南大部分地区可将水量增加。在弱极涡事件前，东亚冬季风显著增强，使我国气温偏冷，降水减少，而弱极涡事件后，我国气温明显回升，中、东部地区和新疆西北部地区降水明显增加。NCEP reanalysis datasets are used to analyze planetary wave activity in the Northern Hemisphere that occurs during the stratospheric abnormal processes and associated characteristics of weather variations over China based on selected strong and weak polar vortices according to the Northern Hemispheric annular mode （NAM） index. The analysis reveals that a downward wave coupling event occurs prior to the strong polar vortex events. During this period, the planetary wavenumberl is reflected to the troposphere, the polar wave guide weakens, and the low-latitude wave guide strengthens. Meanwhile, the E-P flux vector in the middle-high latitudes spreads from the stratosphere to the troposphere.Following the strong polar vortex events, the polar wave guide strengthens, and the low-latitude wave guide weakens to some extent. The upward wave coupling event that occurs prior to the weak polar vortex events strengthens the polar wave guide. Following the events, the planetary wave-1 and the polar wave guide both weaken, and in accordance, the weather of China changes dramatically. Prior to the stratospheric vortex intensification events, temperatures in most parts of China are cooler than normal. The southern region of China is wetter, whereas northwestern Xinjiang and westem Yunnan Province are drier. Following the events, the East Asian winter monsoon becomes stronger, and the cold air spills southward. The precipitable water vapor in southern China decreases and the northwestern region of Xinjiang remains dry, whereas most parts of Yunnan become wetter. In contrast, prior to the stratospheric vortex weakening events, the East Asian winter monsoon is significantly strengthened, the temperature of China is colder than normal, and precipitable water vapor clearly decreases. Following these events, temperatures in China increase sharply, and precipitation in central and eastern China and in northwestern Xinjiang increases significantly.

关 键 词：平流层极涡 北半球环状模 行星波 波动耦合事件 

分 类 号：P466[天文地球—大气科学及气象学]