冬季北极涛动的影响分析  

Influence of Arctic Oscillation on Temperature and Precipitation in Winter

作　　者：杨辉[1] 李崇银[1] 

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学国家重点实验室,北京100029

出　　处：《气候与环境研究》2008年第4期395-404,共10页Climatic and Environmental Research

基　　金：中国科学院大气物理研究所创新基金领域前沿重点项目IAP07120;国家重点基础研究发展规划项目2004CB418303;国家自然科学基金资助项目40875049;上海台风所台风基金2006STB01

摘　　要：采用美国NCEP/NCAR月平均再分析资料、中国气象局160站地面月资料以及美国国家海洋和大气局月平均北极涛动（AO）指数,研究了1979～2008年12～2月AO与该时期北半球大气环流和我国气候的关系。发现当AO异常时,西风带和副热带的环流有很大的差别。当AO异常强时,北太平洋是一对偶极性异常环流：中高纬度为反气旋异常环流,副热带为气旋异常环流。这种形势越到高层越明显,范围也越大。对流层中高层中高纬度的反气旋异常环流西扩到贝加尔湖以东,副热带的气旋异常环流西扩到中印半岛。由于这种异常分布,西太平洋副热带高压偏弱,东亚高空西风急流偏弱,东亚大槽偏弱。乌拉尔山附近是负距平,不利于乌拉尔山高压脊发展。在海平面气压场上,北太平洋为正距平,而在西伯利亚为负距平,阿留申低压和西伯利亚高压偏弱,因此东亚冬季风偏弱。由于冬季风偏弱,导致我国东部、东北、新疆和内蒙古温度偏高。AO异常弱时,环流形势正好相反,冬季风偏强,我国温度偏低。AO的异常也影响我国降水,AO异常强时,除内蒙古、新疆降水偏少外,大部分地区降水偏多,异常降水中心在华南沿海;而当它异常弱时,江南、华南、内蒙古和新疆降水偏多,其他地区降水偏少,异常降水中心位于江南。2008年1月AO活跃,与AO强时平均情况一致,两者在中纬度的东亚有非常好的相似性,都为正距平,表示东亚大槽偏弱;北太平洋的偶极性异常环流对在对流层中、上层也是明显的。最主要的差异在乌拉尔山和西太平洋地区,由于造成2008年1月我国南方持续雨雪冰冻天气重要因素的西太平洋副热带高压、乌拉尔山阻塞高压和冬季风与AO偏强的平均情况相反,因此AO不是造成持续雨雪冰冻天气的原因。Using the NCEP/NCAR reanalysis data,monthly mean Arctic Oscillation（AO） index of National Oceanic and Atmospheric Administration,and the 160 station data of China Meteorological Administration from 1979-2008 Dec-Jan-Feb,the influence of AO on the circulation and temperature and precipitation in the corresponding period are studied.There exists a distinct difference in the flow patterns both in middle and lower latitudes between the positive and negative of AO.Associated with the positive AO,a pair of anomalous circulations occupies the North Pacific,which are an anticyclonic circulation anomaly in middle and high latitudes and an cyclonic circulation anomaly in lower latitudes.This pattern is more obvious in upper levels than that in low levels.The anticyclonic circulation anomaly in middle and high latitudes extends to the east to Lake Baikal and the cyclonic circulation anomaly in lower latitudes extends to the Indo-Chinese peninsula.Because of the pattern,the subtropical high in the Western Pacific（WP）,the East Asian upper westerly jet and the East Asian trough are all weaker.Negative anomalies exist over Ural areas,which is distinctly not favorable to the development of the Ural blocking high.In the sea level pressure,the Aleutian low is weaker with the positive anomalies in the North Pacific,and the Siberian high is also weaker with the negative anomalies in Siberia.So the weaker East Asian winter monsoon results in the higher temperature in East China,Northeast China,Xinjiang Uygur Autonomous Region（XUAR）,Inner Mongolia Autonomous Region（IMAR）.The circulations in the case of negative AO exhibit remarkable difference from WP,even out-of-phase to each other.Because of the stronger East Asian winter monsoon,the temperature in China is lower than normal.The AO influences the precipitation.When the AO index is positive,positive precipitation anomalies occur over China with centre over coastal South China,except XUAR and IMAR.When the AO index is negative,positive precipitation anomalies occur ove

关 键 词：北极涛动 大气环流 气候 雨雪冰冻灾害 

分 类 号：P732[天文地球—海洋科学]