冬季北大西洋涛动对中国春季降水异常的影响  

Influence of Winter North Atlantic Oscillation on Spring Precipitation in China

作　　者：邵太华[1] 张耀存[1] 

机构地区：[1]南京大学大气科学学院,江苏南京210093

出　　处：《高原气象》2012年第5期1225-1233,共9页Plateau Meteorology

基　　金：国家自然科学基金项目(41130963);高等学校博士学科点专项科研基金项目(20100091110003);公益性行业(气象)科研专项(GYHY201006019)共同资助

摘　　要：利用中国397个测站降水资料和NCEP/NCAR再分析资料,采用相关分析、合成分析等方法,研究了冬季北大西洋涛动(NAO)对我国春季降水的影响。结果表明,我国春季降水与前期冬季NAO关系密切,冬季NAO偏强(弱)时,我国东部南方地区春季降水偏多(少),北方地区春季降水偏少(多)。冬季NAO信号通过波列形式传播至东亚地区,使得春季东亚副热带急流和温带急流发生变化,冬季NAO偏强(弱)时,春季东亚副热带西风急流增强(减弱),温带急流减弱(增强)。进一步分析表明,冬季NAO异常会引起春季乌拉尔山高压脊和东亚大槽的变化,导致东亚对流层上层的温度发生变化,并由此产生经向温度梯度异常,这可能是NAO影响东亚高空急流的原因之一。春季东亚对流层上层的气温变冷(暖),使得东亚地区30°-40°N区域产生下沉(上升)运动,20°-30°N区域产生上升(下沉)运动,最终导致我国东部南方地区春季降水偏多(少)、北方地区春季降水偏少(多)。Based on the precipitation data at 397 stations in China and the NCEP/NCAR monthly reanalysis data,the relations between the winter North Atlantic Oscillation（NAO） and the spring precipitation in China using the correlation analysis and composite analysis are studied.The results show that the NAO significantly influence on the variations of spring precipitation in China.Associated with the positive（negative） NAO,the precipitation in South China will increase（decrease） and the precipitation in North China will decrease（increase）.Further analysis indicates that winter NAO can exert notable influence on the atmospheric circulation over East Asia by propagation of wave train.In strong positive（negative） NAO year,the East Asian subtropical westerly jet enhanced（weakened） and the East Asia polar-front jet weakened（enhanced）.The NAO-related atmospheric circulation resulted in the abnormalities of temperatures on 500~200 hPa,cause corresponding variations in meridional gradients of temperature.Perhaps it is one of the reasons why NAO impacts on westerly jet stream over East Asia.The further analysis indicates that upper-level cooling（warming） is closely related to anomalous sinking（rising） motion in 30°-40° N and rising（sinking） motion in 20°-30°N.These changes result in a drier（wetter） condition in the northern China and a wetter（drier） condition in the southern China.

关 键 词：北大西洋涛动 高空急流 中国春季降水异常 

分 类 号：P461[天文地球—大气科学及气象学]