摘要
利用NCEP/NCAR再分析资料和我国160站月平均气温资料,首先采用线性回归的方法分析了从1958至1998年40个冬季北极涛动(AO)与东亚气候异常的关系。结果表明,当AO处于正位相时,东亚地区200hPa的急流明显北跳,东亚大槽显著减弱,而在中国的华北、东北到西伯利亚出现大范围的地表南风异常,使得低空从西伯利亚到我国的东北、华北以及韩国、日本有显著的暖异常;而当AO处于负位相时,则往往出现相反的情形。进一步的相关和合成分析发现,准定常行星波活动可以在AO与东亚气候之间起到桥梁作用。AO可以通过影响中高纬平流层下层的西风强弱,进而影响到准定常行星波的垂直传播,使得对流层下层中高纬地区的行星波振幅发生变化,从而导致低层的西伯利亚高压和阿留申低压同时减弱或增强,最终导致东亚地区异常偏暖或偏冷;其中低层中高纬地区纬向波数2的扰动对西伯利亚高压和阿留申低压的变化起了最主要的作用。作者提出的AO通过影响准定常行星波的活动而导致东亚气候异常的机理,不但强调了西伯利亚高压的贡献,而且特别从波动的意义上强调了阿留申低压的重要性。文中还讨论了值得进一步研究的有关问题。
By using the NCEP/NCAR reanalysis data and the monthly temperature data from 160 China stations, the relationship between the Arctic Oscillation and the climate anomalies over East Asia in the wintertime is firstly studied from 1958 to 1998 with linear regression. It is found that, in the winter of positive AO phase, the East Asian westerly jet stream at 200 hPa jumps northward clearly and the East Asian trough becomes weaker. In the meantime, the surface southerly anomalies appear in the area from Northeast China and North China to Siberia, leading to a warming condition over there. The opposite situations tend to occur in the winter of negative AO phase Further correlation and composite analyses reveal that the quasi-stationary planetary wave activity may play a bridge role in the relationship between the Arctic Oscillation and the climate anomalies over East Asia. First, the AO influences the strength of westerlies in the lower stratosphere over midhigh latitudes. Then the vertical propagation of planetary waves is affected, which leads to the variations in the amplitudes of planetary waves in the lower troposphere over mid-high latitudes. In particular, the wavenumber 2 pattern of planetary waves contributes dominantly to the variability of the Siberian high and the Aleutian low. In the mechanism of AO＇s influence on the climate anomalies over East Asia via the planetary wave activity, the authors emphasize not only the contribution of the Siberian high, but also the importance of the Aleutian low in the context of wave activity. Several questions related to the above-mentioned mechanism are discussed and worth to be studied further.
出处
《大气科学》
CSCD
北大核心
2006年第5期863-870,共8页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40375021
40575026
国家重点基础研究发展规划项目2004CB418303
关键词
北极涛动
东亚气候
准定常行星波
年际变化
Arctic Oscillation, East Asian climate, quasi-stationary planetary wave, interannual variation
