THE NONLINEAR PROPAGATION OF GRAVITY WAVE PACKETS IN DISSIPTIVE ATMOSPHERE
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摘要: 本文对具有高斯分布的重力波波包在耗散大气中的非线性传播过程进行数值模拟和分析,并与重力波波包在无耗大气中非线性传播的数值计算结果进行比较,以辨明耗散在重力波非线性传播过程中所起的作用.数值分析结果表明:尽管存在非线性效应和耗散的共同作用,在整个传播过程中,波包和波相关能量仍然能够自由地向上传输.波相关扰动速度随高度的增加而增加,但是明显小于波包在无耗大气中传播时的结果,并且随着波包的向上传播,背景风场出现明显增强.重力波波包的波能量随时间单调下降,能量传播路径和速度均与重力波波包在无耗大气中非线性传播时的结果一致.可见重力波波包在耗散大气中传播时,波能量传播路径和速度并不受耗散的影响,背景耗散对重力波的作用仅仅限制波振幅的增长,并将波能量传递给背景风场.Abstract: For elucidating the effect of dissipation on the nonlinear propagation of gravitywave-packet, a numerical simulation of nonlinear propagation of a Gaussian gravitywave-packet in a dissipative atmosphere is carried out and compared with that in a nondissipative atmosphere. The numerical analysis shows that for an initially given upgoing gravity-wave-packet, although there exists the joint action of nonlinear interaction and dissipation during the propagation, the whole wave packet and the wave-associated energy keep moving upward. Wave-associated perturbation velocity increases with the increasing height, but the increased perturbation velocity is much less than that in the nondissipative case, on the other hand, the ambient shows an obvious enhancement. The wave-associated energy decreases monotonously with time. The propagation path and velocity of wave-associated energy coincides well with those in the nondissipative case. These indicate that when a gravity-wave-packet propagates in a dissipative atmosphere, there is no obvious effects of dissipation on the energy propagation of gravity wave. The dissipation can only restrict the increment of the disturbance velocity and transmit the wave energy to the ambient.
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Key words:
- Gravity wave packets /
- Dissipation /
- Nonlinear propagation
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