| 东亚2005年和2006年冬季风异常及其与准定常行星波活动的关系 |
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| 引用本文： | 黄荣辉,魏科,陈际龙,陈文.东亚2005年和2006年冬季风异常及其与准定常行星波活动的关系[J].大气科学,2007,31(6). |
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| 作者姓名： | 黄荣辉 魏科 陈际龙 陈文 |
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| 作者单位： | 中国科学院大气物理研究所季风系统研究中心,北京,100080 |
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| 基金项目： | 国家自然科学基金
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国家重点基础研究发展计划(973计划) |
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| 摘 要： | 利用NCEP/NCAR再分析资料系统地分析了2005年与2006年冬季欧亚大陆的气温和东亚冬季风的差别及其与北半球准定常波活动的关系。分析结果表明:2005年冬季欧亚大陆中、高纬度地区气温偏低,东亚冬季风偏强;而2006年冬季欧亚大陆中、高纬度地区气温偏高,出现暖冬,东亚冬季风偏弱。分析结果还表明,这两年冬季东亚冬季风的差别不仅是由于西伯利亚高压和阿留申低压的变异所造成,而且是由于北极涛动(北半球环状模)的变化所造成。并且,作者还从这两年冬季北半球准定常行星波活动的差异,在动力理论上进一步讨论了这两年冬季北半球气候和东亚冬季风差异的机理。结果表明:2005年冬季北半球行星波活动为低指数,准定常行星波在高纬度往平流层传播加强,而往低纬度对流层上层传播减弱,造成了行星波E-P通量在高纬度地区对流层中、上层辐合加强,而在副热带地区对流层中、上层辐散加强,引起了北半球高纬度地区极锋急流减弱,而副热带急流加强,这有利于西伯利亚高压的发展,从而引起了东亚冬季风增强;相反,2006年冬季北半球行星波活动为高指数,准定常行星波在高纬度往平流层传播减弱,而往低纬度对流层上层传播加强,造成了行星波E-P通量在高纬度地区对流层中、上层辐散加强,而在副热带地区对流层中、上层辐合加强,引起了北半球高纬度地区极锋急流加强,而副热带急流减弱,这不利于西伯利亚高压的发展,从而引起了东亚冬季风减弱。
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| 关 键 词： | 东亚冬季风 西伯利亚高压 准定常行星波 E-P通量 |
The East Asian Winter Monsoon Anomalies in the Winters of 2005 and 2006 and Their Relations to the Quasi-stationary Planetary Wave Activity in the Northern Hemisphere |
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| HUANG Rong-Hui,WEI Ke,CHEN Ji-Long,CHEN Wen.The East Asian Winter Monsoon Anomalies in the Winters of 2005 and 2006 and Their Relations to the Quasi-stationary Planetary Wave Activity in the Northern Hemisphere[J].Chinese Journal of Atmospheric Sciences,2007,31(6). |
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| Authors: | HUANG Rong-Hui WEI Ke CHEN Ji-Long CHEN Wen |
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| Abstract: | The NCEP/NCAR reanalysis data are used to analyze the difference between the surface air-temperature in middle and high latitudes over the Eurasian continent and the East Asian winter monsoon in the winters of 2005 and 2006(December-February) and their relations to the quasi-stationary planetary wave activity during these two winters.The results show that the surface air-temperature in middle and high latitudes over the Eurasian continent was below normal,and the East Asian winter monsoon(EAWM) was strong in the winter of 2005;but in the winter of 2006,the surface air-temperature was above normal and anomalously warm winter occurred in this region,and the EAWM was weak.The results also show that the obvious difference of the EAWM between these two winters is closely associated with the Arctic Oscillation(AO),and also the opposite variability of the Northern Annular Mode(NAM).In the winter of 2005,the polar front jet stream over high latitudes of the Northern Hemisphere was weaker while the subtropical jet stream was stronger.This caused the stronger Siberian high and the Aleutian low,thus,the EAWM was strong.However,in the winter of 2006,the polar front jet stream over high latitudes of the Northern Hemisphere was stronger;while the subtropical jet stream was weaker,causing the weaker Siberian high and the Aleutian low,thus,the EAWM became weak.Furthermore,the physical mechanism of the difference of the boreal climate and the EAWM between these two winters is dynamically discussed further from the difference of quasi-stationary planetary wave activity.The results show that the planetary wave activity index(PWA index) over the Northern Hemisphere in the winter of 2005 was negative,i.e.,low PWA index,the propagation of quasi-stationary planetary waves into the stratosphere over high latitudes of the Northern Hemisphere was strong,while its propagation into the upper troposphere over low latitudes was weakened.This caused an anomalously strong convergence of E-P fluxes of quasi-stationary planetary waves over high latitudes of the Northern Hemisphere and an anomalously strong divergence of the E-P fluxes over low latitudes,which led to weakening of the polar front jet stream and strengthening of the subtropical jet stream in the winter of 2005.Oppositely,in the winter of 2006,the PWA index over the Northern Hemisphere was positive,i.e.,high PWA index,the propagation of quasi-stationary planetary waves into the stratosphere over high latitudes of the Northern Hemisphere became weak,and its propagation into the upper troposphere over low latitudes was strengthened.This caused an anomalously strong divergence of E-P fluxes of quasi-stationary planetary waves over high latitudes of the Northern Hemisphere and an anomalously strong convergence of the E-P fluxes over low latitudes,which led to strengthening of the polar front jet stream and weakening of the subtropical jet stream in the winter.Therefore,due to the difference of quasi-stationary planetary wave activity between these two winters,the EAWM in the winter of 2006 was different from that in the winter of 2005. |
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| Keywords: | East Asian winter monsoon the Siberian high the quasi-stationary planetary waves E-P flux |
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