【作者】 覃军；

【导师】 王盘兴；

【作者基本信息】 南京信息工程大学 ， 气象学， 2005， 博士

【摘要】 利用NCEP/NCAR再分析资料和台站观测资料分析了北极涛动的时空结构,研究了中纬度海气耦合的若干特征,并就中高纬度大气环流异常对中国东部夏季降水的影响进行了讨论。主要采用诊断方法(谐波分解、奇异值分解、复自然正交函数分析、合成分析及相关分析等),得到如下主要结论: 1.分析了北、南半球热带外大气环流气候及异常的时空结构。极涡是该区域四季存在、冬强夏弱、向上延伸至平流层下部的基本环流系统。而北、南半球极地涛动(AO、AAO)给出了极涡异常的时空特征,它们是与北大西洋涛动(NAO)、北太平洋涛动(NPO)和南方涛动(SO)相类似的遥联系统。 2.极地涛动具有明显的纬向对称性和冬强夏弱的季节变化。极地涛动指数给出的极涡异常存在明显的年际变化、年代际变化,它们的空间型表明,年际变化主要与极地环流异常有关(北极涛动),而年代际变化主要与副热带环流异常有关(副热带涛动)。极地涛动的半球际差异明显地表现在:1)纬向对称环流异常分量主模态年变化北半球强于南半球;2)55N,500hPa上的纬向非对称环流异常分量的传播特征是,北半球以驻波为主而南半球以东传波为主。 3.本文给出的极涡位置指数能较好地描述中高纬度环流异常的变率。冬季极涡异常变化对应于对流层中高纬度环流异常的型为北极涛动和副热带涛动。 4.在年际、年代际时间尺度上,北半球夏季北大西洋和北太平洋海表温度异常间均存在显著相关联系。北极涛动和副热带涛动与它们存在显著相关,这种相关可以从与海表温度异常模态耦合的1000hPa风场以及与此相应的极涡异常得到说明。 5.分析表明,北极涛动和副热带涛动与北大西洋、北太平洋两个时间尺度上的SST遥联主模态间存在显著相关联系,极地、副热带环流异常分别与SST年际、年代际遥联的相关显著。因此北极涛动和副热带涛动是沟通北大西洋、北太平洋SST异常的“大气桥”。 6.在年际、年代际时间尺度上,夏季北极涛动和副热带涛动与我国东部降水异常间存在明显的同时和时滞的相关联系。同期关系中,年际时间尺度上,长江流域降水与副热带涛动有显著的相关(0.425);年代际时间尺度上长江流域降水与北极涛动、副热带涛动都有显著的相关(0.668和0.749)。其中,同时性的相关联系与北大西洋、北太平洋海气祸合导致的我国东部夏季风异常有关,它导致相应时间尺度上两大涛动与我国东部夏季降水的显著相关联系。关键词中高纬度环流异常海表温度异常遥相关时空特征海气祸合北 极涛动、南极涛动更多还原

【Abstract】 In this paper, the spatial-temporal structure of Arctic Oscillation is analyzed; the effect of the mid-high latitude atmospheric circulation anomaly to the summer rainfall of eastern China is discussed. During the analyses, a few of diagnostic methods such as harmonic wave analysis, SVD, complicated EOF (CEOF), composite analysis and correlation analysis are used. The main results are as the followings:1 ) The climatological and anomalous spatial-temporal characteristic ofthe atmospheric circulation in the extra-tropical region is analyzed. Polar vortex is a basic circulation system which exists in every season (strong in winter and weak in summer) and can extend to the lower level of stratosphere. The polar oscillations in north and south hemisphere (AO, AAO) give the spatial-temporal characteristic of the polar vortex anomaly. The polar oscillation is a teleconnection system which similar to that of North Atlantic Oscillation (NAO), North Pacific Oscillation (NPO)and Southern Oscillation (SO).2) Polar oscillation are obviously zonal symmetry and seasonal variation (strong in winter and weak in summer). Polar anomaly, showed by polar oscillation index, has obvious inter-annual and inter-decadal variation. The space patterns show that the inter-annual variation is related with polar circulation anomaly (AO) and the inter-decadal variation is related with sub-tropical circulation anomaly (sub-tropical oscillation, STO). The differences of the polar oscillation between north and south hemisphere are obviously reflected in that: (1) the annual variation of principal pattern of zonal symmetric circulation anomaly component is morn stronger in north hemisphere than in south hemisphere; (2) In 55°N, 500hPa level, the propagation characteristic of zonal asymmetric circulation anomaly component is standing wave in north hemisphere and eastward wave in south hemisphere.3) In this paper, the index of polar vortex position is introduced. This index can preferably describe the variability of mid-high latitude circulation anomaly. The anomalous variation of polar vortex in winter corresponds to the situation that the pattern of mid-high latitude circulation anomaly in troposphere is AO and STO.4) In the inter-annual and inter-decadal time scale, the summer SSTA between north Atlantic and north Pacific is significantly correlated. AO and STO also significantly correlated with SSTA index. This correlation can be illuminated by the 1000hPa wind field which is coupling with the SSTA pattern and the corresponding polar vortex anomaly.5) The analyses show that AO and STO are significantly correlated with the SST’s principal teleconnection pattern between north Atlantic and north Pacific in inter-annual and inter-decadal time scales; circulation anomaly in pole and sub-tropical region is significantly related with SST’s inter-annual and inter-decadal teleconnection respectively. So AO and STO is the "atmospheric bridge" which connects the north Atlantic SSTA with north Pacific SSTA.6) Under the inter-annual and inter-decadal scale, summer AO and STO have distinct contemporary and lag correlation with precipitation anomaly in eastern China. For the contemporary relationship, under the inter-annual scale the precipitation anomaly in the Changjiang valley is markedly related with STO (correlation coefficient is 0.425) and under the inter-decadal scale the precipitation anomaly in the Changjiang valley is strongly correlated with NA and STO(correlation coefficient is 0.668 and 0.749). Among those correlations, the contemporary correlations is related with eastern China summer monsoon anomaly resulted from the ocean-atmosphere coupling of north Atlantic and north Pacific, resulting in the evident relationship between the two oscillations and the summer precipitation in eastern China.更多还原