声重波在垂直切变风场中的传播与演变

本文根据时空变化风场中声重波演变的基本方程,详细讨论了声重波的基本参量在垂直切变风场中的变化方式。结果表明,沿群路径上波长、相速和传播方向的变化取决于风场的垂直结构以及波风之间的相对方位。声重波扰动动能的变化与波空间尺度的变化存在一定的关系。对于上行重力波分支,波包动能的增加伴随着波长变长,波包动能减小伴随着波长变短;对于上行的声波分支,情况则相反。文中还讨论了常定的声重波波列在垂直切变风场中的传播问题,分析表明,声重波能量密度增加伴随着本征频率减小,能量密度减小伴随着本征频率增加。 

Propagation and Evolution of an Acoustic Gravity Wave in a Region of Wind Shear

By using the fundamental equations describing the evolution of an acoustic gravity wave (AGW) packet in an ambient wind,the variation characteristics of AGW’s essential parameters in a region of wind shear are studied.It is shown that the variations of wavelength,phase velocity and propagation direction depend on the vertical structure of the wind and also on the direction of the wave with respect to the wind.The variation manner of AGW kinetic energy is related to the variation in the spatial scale of AGW.For the upgoing gravity branch,an increase of kinetic energy of the wave packet is accompanied by an increase of the wavelength,while a decrease of the kinetic energy is accompanied by a decrease of the wavelength.For the upgoing acoustic branch,the situation is just opposite.It is also discussed that an AGW wavetrain propagates in the region of wind shear.It is shown that an increase of AGW energy density is accompanied by a decrease of intrinsic frequency,while a decrease of AGW energy density is accompanied by an increase of intrinsic frequency.