低空急流和非均匀层结条件下重力惯性波的传播与发展

THE INFLUENCE OF LOW-LEVEL JET STREAM AND NONUNIFORM STRATIFICATION ON THE PROPAGATION AND DEVELOPMENT OF INERTIA-GRAVITY WAVE

摘要:

本文从基流背景下线性化Boussinesq方程组出发,采用WKBJ方法,首先求得重力惯性波的广义波作用量变化方程及波参数随波包的变化方程,讨论了基流切变对重力惯性波传播和发展的影响;然后用Runge-Kutta方法讨论了不同层结(含降水影响)下重力惯性波的传播路径。得到了降水强度大、静力稳定度小的区域对重力惯性波有“吸引”作用,因而引起重力惯性波能量的集中,进而触发和强化对流天气的结论。

Abstract:

In this paper linearized Boussinesq form equations with y direction basic flow are investigated by means of WKBJ method. A wave action density and the equations which describe the changing of wave parameters are obtained. The propagation and development of inertia-gravity wave packet are discussed. In addition, the ray tracing method is used to discuss the influene of nonuniform stratification on the propagation of wave packet. The main conclusions ares A) The downstream propagating waves from the jet axis to either side of the jet are amplified, while the upstream propagting waves are weakened. (B) when the sources emitting the wave packets are located far away from the jet axis, the downstream propagating waves from the sources on both sides to axis are weakened, while the upstream propagating waves are amplified. (C) the area of small stratificaton or area with precipitation attracts the energy of inertia-gravity wave and then the convection and storm are triggered off and activated.