The Interannual Variability of Summer Rainfall in the Arid and Semiarid Regions of Northern China and Its Association with the Northern Hemisphere Circumglobal Teleconnection   总被引：2，自引：0，他引：2  

HUANG Gang  LIU Yong  HUANG Ronghui 《大气科学进展》2011,28(2):257-268

Using the latest daily observational rainfall datasets for the period 1961–2008, the present study investigates the interannual variability of June–September (JJAS) mean rainfall in northern China. The regional characteristics of JJAS mean rainfall are revealed by a rotated empirical orthogonal function (REOF) analysis. The analysis identifies three regions of large interannual variability of JJAS rainfall: North China (NC), Northeast China (NEC), and the Taklimakan Desert in Northwest China (TDNWC). Summer rainfall over NC is shown to have displayed a remarkable dry period from the late 1990s; while over NEC, decadal-scale variation with a significant decreasing trend in the last two decades is found, and over TDNWC, evidence of large interannual variability is revealed. Results also show that the interannual variability of JJAS rainfall in northern China is closely associated with the Northern Hemisphere circumglobal teleconnection (CGT). Correlation coefficients between the CGT index and regional-averaged JJAS mean rainfall over NC and NEC were calculated, revealing values of up to 0.50 and 0.53, respectively, both of which exceeded the 99% confidence level.  相似文献   

Connections between the Eurasian teleconnection and concurrent variation of upper-level jets over East Asia   总被引：3，自引：0，他引：3  

WANG Ning  ZHANG Yaocun 《大气科学进展》2015,32(3):336-348

The variation of the East Asian jet stream(EAJS) associated with the Eurasian(EU) teleconnection pattern is investigated using 60-yr NCEP–NCAR daily reanalysis data over the period 1951–2010. The EAJS consists of three components: the polar front jet(PFJ); the plateau subtropical jet(PSJ); and the ocean subtropical jet(OSJ). Of these three jets over East Asia,the EU pattern exhibits a significant influence on the PFJ and OSJ. There is a simultaneous negative correlation between the EU pattern and the PFJ. A significant positive correlation is found between the EU pattern and the OSJ when the EU pattern leads the OSJ by about 5 days. There is no obvious correlation between the EU pattern and the PSJ. The positive EU phase is accompanied by a weakened and poleward-shifted PFJ, which coincides with an intensified OSJ. A possible mechanism for the variation of the EAJS during different EU phases is explored via analyzing the effects of 10-day high-and low-frequency eddy forcing. The zonal wind tendency due to high-frequency eddy forcing contributes to the simultaneous negative correlation between the EU pattern and the PFJ, as well as the northward/southward shift of the PFJ. High- and low-frequency eddy forcing are both responsible for the positive correlation between the EU pattern and the OSJ, but only high-frequency eddy forcing contributes to the lagged variation of the OSJ relative to the EU pattern. The negative correlation between the EU pattern and winter temperature and precipitation anomalies in China is maintained only when the PFJ and OSJ are out of phase with each other. Thus, the EAJS plays an important role in transmitting the EU signal to winter temperature and precipitation anomalies in China.  相似文献   

Global nonlinear and nonstationary climate change effects on regional precipitation and forest phenology in Panama,Central America          下载免费PDF全文

Ni‐Bin Chang  Miguel Valdez Vasquez  Chi‐Farn Chen  Sanaz Imen  Lee Mullon 《水文研究》2015,29(3):339-355

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盛夏北极边缘海冰与来年冬季NAO之联系          下载免费PDF全文

胡春迪  张成扬  陈大可  杨清华 《海洋学研究》2018,36(4):8-16

许多研究认为,只有北大西洋涛动(NAO)是一种具有物理意义的模态,而北极涛动(AO)则是EOF分解得到的一种统计假象模态。为了从一个新的角度进一步探讨二者的差别,我们运用附条件的最大协方差分析(CMCA)统计了前期北极边缘海冰密集度(MSCI)与来年冬季NAO之间的跨季节遥相关关系,其中的ENSO信号和线性趋势已经在分析之前被去除。统计显著性结果表明:冬季负位相的NAO信号可以追溯到6个月前自盛夏开始至早冬季节北极MSCI异常的逐步演变。然而根据先前的研究,北极海冰异常仅可以超前冬季AO 大概4个月表现出显著信号。这表明盛夏北极MSCI的持续异常对来年冬季NAO的影响比对AO更强,同时也从另一个角度证实了AO与NAO确实存在差异。进一步分析还表明,前期MSCI异常的逐步演变主要与海表面热通量及气温异常有关。此外,我们还重新审视了负位相的NAO对北半球冬季气候异常的影响以及可能的物理机制。  相似文献   

Circulation on the newfoundland continental shelf     

Brian Petrie  Carl Anderson 《大气与海洋》2013,51(2):207-226

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大气环状模对夏季中国大陆登陆热带气旋频数气候变化的影响     

马圆  余锦华  方珂  董晓云 《气象科学》2020,40(2):264-269

采用1949—2016年7—8月美国国家环境预报中心及大气研究中心(NCEP/NCAR)再分析资料与中国气象局(CMA)上海台风所整编的热带气旋最佳路径数据集,研究大气环状模(Circumglobal Teleconnection,CGT)与中国大陆地区登陆热带气旋(Tropical Cyclone,TC)频数气候变化的关系。定义200 hPa经向风经验正交展开(EOF)的第一模态为CGT,其时间系数为环状模指数(Circumgolbal Teleconnection Index,CGTI)。CGT在北半球中纬度地区有5个异常中心,CGTI在1949—2016年呈明显的下降趋势,且存在一个2~3 a的周期振荡。CGT与大尺度环流异常存在密切的联系。研究表明:CGTI与中国大陆登陆TC频数气候变率具有显著的正相关,即CGTI表现为正异常时,登陆中国大陆的TC频数增加,反之减少。当CGT表现为正位相时,东亚副热带西风急流增强,急流南侧的反气旋切变增强,使TC登陆过程的活动区域200 hPa的辐散增强,此外,对流层高层Rossby波能量向南传播增强,形成波通量辐合,导致东风异常,产生了东风异常的引导气流和纬向风垂直切变,东风切变使得切变减小,增加了TC登陆中国大陆的可能性。  相似文献   

江苏冬夏极端气温与大气环流及海温场的遥相关   总被引：14，自引：3，他引：14  

何卷雄  丁裕国  姜爱军 《热带气象学报》2002,18(1):73-82

以江苏夏季最高气温和冬季最低气温场为例，研究海气耦合作用对区域气温场异常型态的影响，结果表明，江苏夏季最高气温受到同期海气耦合作用的影响较明显，冬季最低气温受同期海气耦合作用的影响较少；从一定意义上说，夏季最高气温的降低是由于东太平洋遥相关型强度的变化及同期北太平洋海温距平分布型的强度加强所致，而冬季最低气温的升高则是由于WA型及欧亚大陆上空环流型强度的变化及同期北太平洋海温距平分布型的强度减弱所致。  相似文献   

Nino C区秋季海温异常对东亚冬季大气环流的影响   总被引：14，自引：5，他引：14  

陈海山  孙照渤  倪东鸿 《热带气象学报》2002,18(2):148-156

研究了秋季赤道中东太平洋（Nino C区:0～10°S,180～90°W）的SST异常对东亚冬季大气环流的可能影响。在揭示二者联系的基础上,通过分析海温异常所引起的500hPa高度、经向风及纬向风的异常特征,探讨了秋季海温异常影响东亚冬季大气环流的可能途径。研究发现,Nino C区秋季SST异常,能够对东亚及西太平洋地区的大气环流及风场产生显著影响,进而影响东亚冬季风活动:秋季SST正（负）异常,引起西太平洋地区出现类似负（正）WP遥相关型的环流异常,中纬度纬向西风加强（减弱）,东亚及沿海地区出现异常南（北）风分量,经向风减弱（加强）,最终导致偏弱（强）的东亚冬季风活动。这是海温异常影响东亚冬季大气环流的一种可能途径。  相似文献   

夏季东亚高空急流与太平洋-日本遥相关型的关系   总被引：1，自引：1，他引：1  

钟中  唐筱之  卢伟  陈中一 《气象科学》2015,35(6):672-683

利用NCEP/NCAR和NOAA月平均资料,采用奇异值分解方法分析了夏季东亚高空纬向风场和西北太平洋海表温度(SST)的耦合关系,并据此研究了东亚副热带高空急流和太平洋-日本(Pacific-Japan,PJ)遥相关型的可能联系。合成分析结果表明,东亚副热带高空急流正模态年,急流偏南偏强,对流层上层南亚高压增强东进,中层西太平洋副热带高压加强西伸,菲律宾周边海域SST升高,中纬度黑潮延伸体区SST降低,菲律宾海和热带西太平洋地区对流活动偏弱,日本海和黑潮延伸体海区对流活动增强,对应PJ遥相关型的负位相;而东亚副热带高空急流负模态年,急流偏北偏弱,对流层上层南亚高压减弱西退,中层西太平洋副热带高压减弱东撤,菲律宾周边SST降低,中纬度黑潮延伸体区SST升高,菲律宾海和热带西太平洋地区对流活动强盛,日本海和黑潮延伸体海区对流活动减弱,对应PJ遥相关型的正位相。由于夏季东亚副热带高空急流活动与PJ遥相关型存在关联,PJ遥相关型可能是东亚副热带高空急流响应太平洋海温异常的纽带。  相似文献   

Analysis of the rainfall variability and change in the Republic of Benin (West Africa)     

Yédjinnavènan Ahokpossi 《水文科学杂志》2013,58(15-16):2097-2123

ABSTRACT

The temporal variation and trends of annual rainfall distribution in Benin were examined using data from 1940 to 2015 at six meteorological stations and three raingauges stationed throughout the country. The nonparametric modified Mann-Kendal (MK) and Levene tests were applied to detect trends and heteroscedasticity, respectively. For six of the time series, no significant trends were detected. A Bayesian multiple change points detection approach was applied to the rainfall time series, and most (six of nine) exhibited abrupt change points, corresponding to the alternation between wet (before 1968 and after 1990) and dry (1969–1990) periods. No significant trends or breakpoints and changes in the variance were observed for the spatial average rainfall time series. Seven modified MK trend tests were applied; the trends are affected by the selected MK method and rainfall statistics. Oceanic and/or atmospheric influences on the rainfall in Benin were examined by investigating the correlation between the precipitation time series and several indices. Negative seasonal correlations were determined for the North Atlantic Oscillation, Pacific Decadal Oscillation and Niño3, while positive seasonal correlations were observed for the Southern Oscillation, Antarctic Oscillation and Dipole Mode Index.  相似文献