重力惯性波及其不稳定——急流附近飞机颠簸产生的可能机制

Gravity Wave and Inertial Instability——Possible Mechanism of Atmospheric Turbulence and Airplane Bumps

基于不可压缩流体运动方程组研究了急流附近重力惯性波及其不稳定,结合飞机风速变化方程,分析指出重力波失稳破碎为湍流是飞机颠簸产生的可能机制。斜压大气在急流轴北侧气旋切变区是惯性稳定的,当满足条件σ=f[f-/y]+N2m2/n2<0时,由于天气尺度对流不稳定发展而引起重力惯性波不稳定破碎为湍流,可能是急流北侧气旋切变区对流性天气引起飞机颠簸产生的一种机制。但是在急流轴南侧反气旋切变区是惯性不稳定的,当满足条件σ=f[f-/y]+N2m2/n2<0时,可能由于惯性不稳定的作用,急流重力波不稳定发展破碎为湍流,可能是急流南侧反气旋气流中晴空湍流和飞机颠簸产生和发展的一种机制。揭示了急流附近晴空湍流和飞机颠簸产生的物理本质,有利于增强航空飞行颠簸的预测能力。

The gravity waves associated with jet and aircraft upset are investigated by using an extended normal mode method. The analytical solutions indicate that gravity waves may be unstable and lead to breaking and turbulence when the stratified flow satisfies the inertial unstable conditions on the southern part of the jet axes, where the wind-shear with the anti-cyclone. However, on the northern part of jet, gravity waves may be unstable and lead to breaking and turbulence when the stratified flow satisfies the convective unstable conditions, where the wind-shear with cyclone. Most importantly, the relationship of airplane upset with wind field under the various atmospheric stability conditions is discussed and help to improve the ability of forecasting the clear air turbulence and airplane upset.