摘要
采用NCEP/NCAR(National Centers for Environmental Prediction/National Centers for Atmospheric Research)再分析资料,分析了冬季北大西洋涛动(NAO,Northern Atlantic Oscilation)指数、极涡面积(PVA,Polar Vortex Area)指数、极涡强度(PVI,Polar Vortex Intention)指数的变化。研究结果表明:冬季PVA指数基本和NAO指数呈反位相变化,冬季PVA指数具有明显的下降趋势;冬季NAO指数、PVA指数、PVI指数都具有多重周期变化特征,具有较为一致的年际、年代际变化周期,都具有准9 a的年代际振荡周期和4~5 a的年际振荡周期;在强(弱)NAO指数年份,极地地区500 hPa高度场降低(升高),冷空气向极地地区收缩(冷空气向中纬度活动),PVA指数偏小(偏大),而PVI指数偏大(偏小),在年际变化尺度上,NAO与极涡的关系主要表现在极涡为2极分布,且极涡偏向大西洋侧,太平洋侧较弱,为典型的北大西洋局地的NAO分布;在1988年左右,冬季NAO指数有一突变现象,冬季PVI指数在1976年前后有一突变现象,比冬季NAO指数的气候突变要稍微提前,冬季PVA指数没有明显的突变现象。NAO指数突变后60°N以北的距平中心位置更靠东,强度更大。在年代际变化尺度上,极涡表现为3极,其显著变化中心主要表现在40°N附近的异常高中心,且环球一圈,没有极涡的优势偏心特征。
Using the NCEP/NCAR reanalysis data,the variability of winter time NAO index,PVA index,PVI index are studied.The result shows that Changes in winter time PVA index are in anti-phase with that of winter time NAO index,and winter time PVA index has obvious ascending tendency;All the three indexs have multi-periods.They have accordant inter-annual period of 4～5 a and inter-decadal period of 9 a;In the higher(lower)phase years of NAO index,the cumulative anomalies of polar area on 500 hPa are negetive(positive),the height field falls(raises),and PVA index is weaker(stronger),while PVI index is stronger(weaker).In annual scale,the relationship between the NAO and the Polar Vortex is that the Polar Vortex is arranged to two poles,and it leans to the Atlantic Ocean while the Pacific Ocean part is weaker.This is typical North Atlantic local NAO distribution;Aroud the year 1988,winter time NAO index has an abrupt change,and winter time PVI index has an abrupt change around 1976 which is a little earlier than the abrupt change of NAO index,and winter time PVA index dosen't have obvious abrupt change;After the abrupt change of NAO index,the anomaly center north of 60°N moves eastward and becomes stronger.In decadal scale,the Polar Vortex is arranged to three poles,and its obvious centers of variation which surround the global around 40°N are mainly on the anomaly centers of high value.In addition,there is no advantage eccentric structure of the Polar Vortex.
出处
《中国海洋大学学报（自然科学版）》
CAS
CSCD
北大核心
2009年第S1期281-286,296,共7页
Periodical of Ocean University of China
基金
国家自然科学基金项目(4057016)
国家基础研究发展计划项目(2005CB422302)资助
关键词
北大西洋涛动
极涡
年际变化
年代际变化
North Atlantic Oscillation(NAO)
polor vortex
inter-annual variability
inter-decadal variability
