在对逐日气象资料进行纬向谐波分析的基础上,对比和讨论了2007/2008年冬季强极涡期间和2008/2009冬季弱极涡期间平流层和对流层不同波数的行星波的变化特征,特别关注强极涡或弱极涡发生之后,500 hPa沿60°N和30°N行星波1波和2波振幅和位相的差异,以及相应的500 hPa位势场的差异,进而讨论为什么不同的平流层极涡异常会对东亚有不同的影响,特别讨论为什么同一种极涡异常,对我国南北方近地面气温的影响会不同.结果表明:平流层极涡发生异常时,平流层行星波活动有明显的异常.随着极涡异常的下传,对流层行星波的振幅和位相也有明显的变化,而且,对于不同的纬度带,其变化又有不同,表现为:2008年1月强极涡发生之后,500 hPa行星波Ⅰ波和2波的扰动都向南伸,而2009年1月的弱极涡(SSW)期间和之后,1波和2波的扰动都偏北;在对流层,强极涡和弱极涡发生之后不但行星波1波和2波的振幅有所差异,其位相也有明显的不同.特别是,其位相的差异还随纬度而变化.就同一年(或者说对于同是强极涡或者同是弱极涡)而言,无论是1波还是2波,在60°N和30°N附近的扰动相比,几乎反位相.这样就使得它们的500hPa位势场也有明显不同:在东半球,主要表现为乌拉尔高压和东亚大槽的强度和位置不同.2008年1月强极涡发生之后,乌拉尔高压和东亚大槽东移,不利于冷空气向欧亚大陆北部(包括我国北方)的输送,使这些地区的温度偏高;而2009年1月弱极涡之后,东亚大槽西退,利于冷空气向欧亚大陆北部输送,导致这些地区较冷.对于同一种极涡异常(如2008强极涡或者2009弱极涡)由于南方和北方行星波扰动的位相不同,对南方和北方冷暖空气的输送也就不一样.所以同一种极涡异常对(我国)南北地区的温度影响是不同的.
Based on the zonal harmonic analysis of daily meteorological data, we compared and discussed the variation characteristics of the planetary wave for different wavenumbers in the stratosphere and troposphere during the strong polar vortex period in the winter of 2007/2008 and the weak polar vortex period in the winter of 2008/2009. We particularly focused on the amplitude and phase variation of the planetary wave for wavenumber-1 and wavenumber-2 along 60°N and 30°N, as well as the different 500-hPa geopotential height fields after the occurrence of the strong polar vortex and the weak polar vortex. Furthermore we discuss the reason for the different stratospheric polar vortex anomalies and the different effects on the weather and climate in eastern Asia. Finally, we investigated why this stratospheric polar vortex anomaly would cause different variations in south and north China surface temperatures. Our results show that following the stratospheric polar vortex anomaly, the planetary wave activities in the stratosphere clearly changed. The downward propagation of the abnormal polar vortex caused amplitude and phase variations in the tropospheric planetary wave and these variations are different along different latitudes. It appears that the planetary wave perturbations for wavenumber-1 and wavenumber-2 in the 500-hPa fields extended southward after the strongest polar vortex in January 2008. During and after the weakest polar vortex in January 2009, however, the planetary wave perturbations for wavenumber-1 and wavenumber-2 in the 500-hPa fields are located on the northern side. In the troposphere, the amplitude of the planetary wave is different for wavenumber-I or wavenumber-2 and their phases are also clearly changed after the strong and weak polar vortex. These phase difference change especially with latitude. For the same year (that is say, for the same strong polar vortex in 2008 or same weak polar vortex in 2009), the planetary wave phase near 60°N is almost opposite to that near 30°N regardless o