北极涡年代际变化及其与我国春季降水的关系   总被引：8，自引：0，他引：8  

张恒德  高守亭  张友姝 《气候与环境研究》2006,11(5):593-604

基于NCEP/NCAR的500hPa再分析高度场资料计算出多年北半球及各分区的极涡面积和强度,利用线性倾向估计、小波分析及二项式滑动平均分析极涡及我国春季降水的年代际变化特征,并采用奇异值分解讨论同期及前期极涡对我国春季降水的影响。各季节极涡面积及强度均存在显著的年代际变化,在20世纪70年代中期之前有上升趋势,而后出现下降的趋势;但极涡面积总体上有显著的线性变小趋势。在60年代中前期极涡位置偏向亚欧大陆,在90年代中后期极涡位置有偏向太平洋和大西洋一带趋势。我国160站平均春季降水量经历较明显的3次上升过程和4次下降过程;华南、西南地区春季降水趋势与长江流域、黄河流域呈现两种相反的分布型;在20世纪60年代中前期、90年代初及末期,长江流域、黄河流域春季降水量偏多,而在80年代末期、90年代中期及本世纪初,华南、西南地区出现偏多。在春季,若II区(150°E～120°W)极涡面积异常大,I区(60～150°E)、III区(120～30°W)极涡强度异常弱,长江、黄河之间中游地区的降水出现负距平,广东、福建沿海降水出现正距平。前期冬季极涡比夏、秋季极涡对我国春季降水的影响更明显,特别是前冬北美区、大西洋欧洲区极涡面积的影响。  相似文献   

东亚夏季风的自然变率——NCARCam3模拟结果分析     

曾刚  孙照渤  林朝晖  朱艳峰  李春晖 《南京气象学院学报》2009,32(4):498-506

利用季节循环的全球观测海表温度及海冰驱动NCARCam3全球大气环流模式的100a模拟结果,通过定义东亚夏季风指数,分析了模拟的大气内部变化中东亚夏季风的变化特征。结果表明：模拟的东亚夏季风自然变率主要表现为3—7a较显著的年际周期,并具有较明显的年代际变化特征。在弱夏季风年代,亚洲大陆海平面气压增强,日本附近及东亚沿海地区海平面气压降低;500hPa位势高度上,欧洲地区为负高度距平,里海附近地区为正高度距平,日本及其以东太平洋为负高度距平,易形成类似欧亚（EU）型的遥相关波列。在强夏季风年代,其环流异常分布基本与弱夏季风年代相反。模拟的东亚夏季风变化与夏季大气内部500hPa高度场上EU型遥相关波列的关系密切。  相似文献   

华北盛夏降水年代际变化与南半球环流异常的关系   总被引：1，自引：0，他引：1  

于勇  牛生杰  刘海文  吴自越 《南京气象学院学报》2009,32(5):661-666

利用NCEP/NCAR再分析资料和中国160个台站降水资料,分析了华北盛夏降水与南半球马斯克林高压、澳大利亚高压的年际关系。结果表明,华北盛夏降水和马高、澳高在年际变化尺度上都有着显著的负相关关系,且这种关系存在年代际变化,并重点分析了与华北盛夏降水年代际变化相对应的南半球环流异常型的特征。  相似文献   

NCEP/NCAR再分析资料中北半球夏季海平面气压的年代际变化   总被引：1，自引：0，他引：1  

邓伟涛  孙照渤  倪东鸿  刘向文 《南京气象学院学报》2009,32(2):239-245

NCEP/NCAR再分析资料集中1948—2005年北半球夏季海平面气压（sea level pressure,SLP）场具有明显的年代际变化特征,主要在东亚和北非大陆地区以及极地地区。20世纪60年代中后期和70年代中后期夏季SLP场有两次跃变过程。对于北半球夏季SLP的这次年代际变化过程而言,20世纪60年代末首先于北欧地区出现距平变化,然后逐渐向东南方向移动,70年代早期贝加尔湖地区开始出现正距平信号,之后这种正距平信号开始往南移,70年代中期东亚大陆出现正距平中心。另外,20世纪60年代中期西北大西洋SLP距平也开始了转变,之后分别向南、北移动,于70年代早期加强了北欧的正距平强度,同时非洲北部也开始了SLP距平的转变。  相似文献   

Variability of Northeast China river break-up date   总被引：5，自引：0，他引：5  

王会军  孙建奇 《大气科学进展》2009,26(4):701-706

This paper investigates the variability of the break-up dates of the rivers in Northeast China from their icebound states for the period of 1957–2005 and explores some potential explanatory mechanisms. Results show that the break-up of the two major rivers(the Heilongjiang River and Songhuajiang River) was about four days earlier,and their freeze-up was about 4–7 days delayed,during 1989–2005 as compared to 1971–1987.This interdecadal variation is evidently associated with the warming trend over the past 50...  相似文献   

An Analysis of Interdecadal Variations of the Asian-African Summer Monsoon          下载免费PDF全文

SONG Yan  JI Jinjun  SUN Xia 《Acta Meteorologica Sinica》2008,22(3):317-328

The response of the Asian-African summer monsoon(AASM)to the fast global warming in the 1980s is studied based on several datasets,which span a long time period of nearly 100 yr,with two special periods 1980-1985 and 1990-1995 being focused on.Wavelet analyses are employed to explore the interdecadal variations of the AASM.It is found that after the mid-1980s.the global annual mean surface temperature rises more significantly and extensively over most parts of the African Continent,north of the Indian Ocean,and the Eurasian Continent excluding the Tibetan Plateau.Correspondingly,the global precipitation pattern alters with increased rainfall seen over the Sahel and North China in 1990-1995,though it is not recovered to the level of the rainy period before the mid-1960s.Changes of monsoonal circulations between the pre-and post-1980s periods display that,after the fast global warming of the 1980s,the African summer monsoon intensifies distinctly,the Indian summer monsoon weakens a little bit,and the East Asian summer monsoon remains almost unchanged.The summer precipitation over the Asian-African Monsoon Belt(AAMB)does not change in phase coherently with the variations of the monsoonal circulations.Wavelet analyses of the land-sea thermal contrast and precipitation over North China and the Sahel indicate that interdecadal signals are dominant and in positive phases in the 1960s.1eading to an overall enhanced interdecadal variation of the AASM,although the 1960s witnesses a global cooling.In the 1980s,however,in the context of a fast global warming,interdecadal signals are in opposite phases,and they counteract with each other.1cading to a weakened interdecadal variation of the AASM.After the mid-1960s.the AASM weakened remarkably,whereas after the mid-1980s,the AASM as a whole did not strengthen uniformly and synchronously,because it is found that the interannual variations of the AASM in the 1980s are stronger than those in the 1960s,and they superimposed on the counteracting interdecadal signals,causing different regioils of the AAMB behaving differently.Therefore,the response of the AASM to the accelerated global warming post the mid-1980s is not simply out-of-phase with that after the mid-1960s;it may involve more complicated multiscale physical elements.  相似文献   

Changes in the Diurnal Cycles of Precipitation over Eastern China in the Past 40 Years   总被引：2，自引：0，他引：2  

YUAN Weihu  YU Rucong  LI Jian 《大气科学进展》2013,30(2):461-467

This study analyzed the interdecadal changes in the diurnal variability of summer(June-August) precipitation over eastern China during the period 1966-2005 using hourly station rain gauge data.The results revealed that rainfall diurnal variations experienced significant interdecadal changes.Over the area to the south of the Yangtze River,as well as the area between the Yangtze and Yellow Rivers,the percentages of morning rainfall(0000-1200 LST) to total rainfall in terms of amount,frequency and intensity,all exhibited increasing interdecadal trends.On the contrary,over North China,decreasing trends were found.As a result,diurnal rainfall peaks also presented pronounced interdecadal variations.Over the area between the Yangtze and Yellow Rivers,there were 16 out of 46 stations with afternoon(1200-0000 LST) frequency peaks in the first 20 years of the 40-year period of study,while only eight remained in the latter 20 years.In North China,seven stations experienced the opposite changes,which accounted for about 21% of the total number of stations.The possible causes for the interdecadal changes in diurnal features were discussed.As the rainfall in the active monsoon period presents morning diurnal peaks,with afternoon peaks in the break period,the decrease(increase) of rainfall in the active monsoon period over North China(the area south of the Yangtze River and the area between the Yangtze and Yellow Rivers) may contribute to interdecadal changes in diurnal rainfall variability.  相似文献   

Interdecadal Enhancement of the Walker Circulation over the Tropical Pacific in the Late 1990s     

Buwen DONG  LU Riyu 《大气科学进展》2013,30(2):247-262

The Walker circulation is one of the major components of the large-scale tropical atmospheric circulation and variations in its strength are critical to equatorial Pacific Ocean circulation.It has been argued in the literature that during the 20th century the Walker circulation weakened,and that this weakening was attributable to anthropogenic climate change.By using updated observations,we show that there has been a rapid interdecadal enhancement of the Walker circulation since the late 1990s.Associated with this enhancement is enhanced precipitation in the tropical western Pacific,anomalous westerlies in the upper troposphere,descent in the central and eastern tropical Pacific,and anomalous surface easterlies in the western and central tropical Pacific.The characteristics of associated oceanic changes are a strengthened thermocline slope and an enhanced zonal SST gradient across the tropical Pacific.Many characteristics of these changes are similar to those associated with the mid-1970s climate shift with an opposite sign.We also show that the interdecadal variability of the Walker circulation in the tropical Pacific is inversely correlated to the interdecadal variability of the zonal circulation in the tropical Atlantic.An enhancement of the Walker circulation in the tropical Pacific is associated with a weakening zonal circulation in the tropical Atlantic and vise versa,implying an inter-Atlantic-Pacific connection of the zonal overturning circulation variation.Whether these recent changes will be sustained is not yet clear,but our research highlights the importance of understanding the interdecadal variability,as well as the long-term trends,that influence tropical circulation.  相似文献   

Weakening of Winter North Atlantic Oscillation Signal in Spring Precipitation over Southern China   总被引：2，自引：0，他引：2       下载免费PDF全文

ZHOU Bo-Tao 《大气和海洋科学快报》2013,6(5):248-252

In this study,the relationship between the North Atlantic Oscillation(NAO)in winter(December–February)and the precipitation over southern China(SCP)in the following spring(March–May)was investigated.Results showed an interdecadal change,from strong to weak connection,in their connection.Before the early1980s,they were highly correlated,with a strong(weak)winter NAO followed by an increased(decreased)spring SCP.However,after the early 1980s,their relationship was weakened significantly.This unstable relationship may be linked to the climatological change of East Asian jet.Before the early 1980s,the wave train along the Asian jet propagated the NAO signal eastward to East Asia and affected local upper-tropospheric atmospheric circulation.A strong NAO in winter led to an anomalous anticyclonic circulation at the south side of 30 N in East Asia in spring,resulting in an increase of SCP.In contrast,after the early1980s,the wave train pattern along the Asian jet extended eastward due to strengthening of the climatological East Asian jet.Correspondingly,the NAO-related East Asian atmospheric circulations in the upper troposphere shifted eastward,thereby weakening the linkage between the spring SCP and the winter NAO.  相似文献   

华北夏季降水的年代际变化   总被引：5，自引：1，他引：4       下载免费PDF全文

刘海文  丁一汇 《应用气象学报》2011,22(2):129-137

利用我国740个测站逐日降水资料和NCEP/NCAR逐日再分析资料,使用合成分析等方法,对华北夏季降水的年代际变化特征进行分析。结果表明:华北夏季降水的年代际变化与华北夏季雨带的年代际变化密不可分。在华北夏季降水偏多阶段,华北地区雨带降水量较大,华北雨带能够向西延伸,雨带位置大多数时间能够越过115°E,并且能够接近华北西部边界110°E,位置偏西;而在华北夏季降水偏少阶段,华北雨带降水量偏小,雨带虽然也能够越过115°E,但维持时间不长,且向西延伸并不明显,雨带位置很难接近华北西部边界110°E,位置偏东。华北雨带发生的年代际变化和东亚地区大气环流以及东亚夏季风的年代际变化有关。  相似文献