出 处:《大气科学》2006年第3期361-376,共16页Chinese Journal of Atmospheric Sciences
基 金:国家重点基础研究发展规划项目2004CB418303;国家自然科学基金资助项目40231005;40375021
摘 要:利用NCEP/NCAR再分析资料和大气环流模式(CCSR/NIES AGCM Ver 5.6),对北半球准定常行星波的气候平均态分布进行分析和模拟。再分析资料分析的结果表明:北半球冬季,准定常行星波沿两支波导向上传播,其中一支在对流层上层转向中低纬度传播,另外一支折向高纬度,通过极地波导上传到平流层。其中,1波和2波可以上传到平流层,因而其振幅分布除在中低纬的对流层上层出现一个次大值外,在高纬度平流层中上层会出现一个最大值,3波则主要限制在对流层,其振幅分布除在副热带对流层上层出现一个次大值外,最大值出现在中纬度对流层上层。北半球夏季,整个平流层为东风环流,极地波导不存在,行星波不能上传到平流层,在对流层活动也较弱,1波、2波、3波的传播情况大致相似,表现为在对流层上层由中纬度向赤道地区的传播。相应的振幅分布是,对1波和2波而言,最大值出现在中低纬对流层顶附近,同时在中高纬对流层上层出现一个次大值,而3波的振幅分布正好相反,最大值出现在中高纬对流层上层,次大值则在中低纬对流层顶附近。利用大气环流模式进行的数值模拟表明,模式可以比较好地模拟冬夏季准定常行星波的传播路径,但模拟的北半球冬季沿极地波导向平流层的传播明显偏弱,其结果是对1波、2波而言,高纬度平流层中上层的振幅最大值明显小于再分析资料的数值。文中还讨论了数值模拟与资料分析中行星波的差异可能对大气环流模拟的影响。Recent study indicates that the stratospheric and tropospheric circulations are not isolated, and are dynamically linked in fact, especially in winter. There is evidence showing that the troposphere-stratosphere coupling interaction is closely associated with the quasi-stationary planetary wave activity. For the study of the variation of quasi-stationary planetary wave activity, it is necessary to find out the basic characters of the quasi-stationary planetary wave distribution. But in recent years, the research on the distribution of planetary wave in winter and summer, especially the study based on the observation data and simulation by using AGCM, is very absent. So in this paper, the climatology of quasi-stationary planetary wave in the Northern Hemisphere is analyzed by using NCEP/ NCAR reanalysis data and the simulation with the CCSR/NIES AGCM Ver. 5. 6. By expanding geopotential height into their zonal Fourier harmonics, their zonal mean values and wave amplitudes and phases are gotten at any wavenumbers. Here the sum of zonal wavenumber 1 to wavenumber 3 is used to represent quasi-stationary planetary wave activity. The Eliassen-Palm flux (EP flux) is used as a diagnostic tool, which is a measure of the wave activity propagation. The reanalysis data indicate the planetary wave propagates along two waveguides in winter. One branch bends equatorward in the upper troposphere, the other turns to the high latitudes and propagates upward into the stratosphere along the polar waveguide. The wavenumber 1 and wavenumber 2 can propagate upward into the stratosphere, so the maximum of amplitude appears in the mid-upper stratosphere of high latitudes, and the secondary maximum appears in the upper troposphere of mid-low latitudes. But the wavenumber 3 is restricted in the troposphere, so the amplitude maximum appears in the upper troposphere of middle latitudes, and the secondary maximum is in the upper subtropical troposphere. In summer, there is no polar waveguide because of the eastedies in stratosphere. Hence
分 类 号:P433[天文地球—大气科学及气象学]
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