【摘要】 在赤道β平面近似条件下,使用纬向切变基流下线性化Boussinesq方程组,分析了在纬向切变基流下几种赤道大气波动的稳定性特征。研究结果表明,基本气流的水平切变对赤道大气波动起到不稳定的作用,但是对赤道大气Kelvin波的频率、稳定性以及传播的相速度并不起作用。基本气流的水平切变使得相对于基本气流向东传播的重力惯性内波相速度减慢,而使得相对于基本气流向西传播的重力惯性内波的相速度加快,却造成相对于基本气流向西传播的Rossby波相速度减慢。基本气流的水平切变对于对赤道混合Rossby-重力惯性内波的影响主要取决于纬向波数k值的范围大小。当纬向波数k值较小时,基流的水平切变使得相对于基本气流向西传播的混合Rossby-重力惯性内波相速度加快;而当纬向波数k值较大时,则使得相对于基本气流向西传播的混合Rossby-重力惯性内波相速度减慢。在半地转近似下,风速水平切变的存在,会使得波长较大(纬向波数k→0)的赤道Rossby波相对于基本气流向西传播的相速度减慢;而风速垂直切变的存在,必然会引起这种波长较大(k→0)的Rossby波出现不稳定增长,同样也会造成赤道Rossby波相对于基本气流向西传播的相速度减慢。最后通过扰动发展能量方程,说明了基本气流的水平切变和垂直切变可以为扰动的发展提供能量来源。更多还原

【Abstract】 By use of the linearized atmospheric equations of Boussinesq approximation on the equatorial β-plane in a zonal shear basic flow,study is undertaken of the stability features of several kinds of equatorial atmospheric waves.Results suggest that 1)the horizontal shear basic flow exerts unstable impact on these atmospheric waves but no effect on the stability and phase velocity of equatorial Kelvin waves;2)the zontal shear decelerates (accelerates) the phase velocity of internal inertial gravity waves propagating eastward(westward) with respect to the basic flow but slows down the west-propagating phase velocity of Rossby waves;3)the zonal shear of basic flow influences equatorial mixed Rossby-internal inertial gravity wave mainly through zonal wavenumber k,with smaller(larger) k responsible for the acceleration(deceleration) of the phase velocity of the mixed-type wave propagating westward with respect to basic flow;4)under the semi-geostrophic approximation the horizontal wind shear leads to that the equatorial Rossby wave with a smaller zonal wavenumber(k→0) exhibits the deceteration of westward propagating phase velocity while in the presence of vertical wind shear,the unstable growth as well.Finally,through the analysis of the equation of energy we demonstrate that through horizontal and vertical shears,the basic flow furnishes the development of disturbances with energy.更多还原