McCarthy D R, Lashmore-Davies C N, Thyagaraja A
Southeastern Louisiana University, Hammond 70402, USA.
Phys Rev Lett. 2004 Aug 6;93(6):065004. doi: 10.1103/PhysRevLett.93.065004.
The generalized Charney-Hasegawa-Mima equation is unstable to a four wave modulational instability whereby a coherent, monochromatic drift wave can drive a band of modes and associated zonal flows unstable. Although initially the fastest growing modes dominate, a secondary nonlinear instability later drives the longest wavelength zonal flow and its associated sidebands at twice the growth rate of the fastest growing modulationally unstable modes. This results in a direct transfer from strongly unstable short wavelength modes to the weakly unstable long wavelength modes, which drains the short wavelength pump energy. A related but less efficient direct enstrophy cascade generates very short wavelength modes lying outside the band of modulationally unstable modes.
广义的查尔尼-长谷川-三岛方程对于四波调制不稳定性是不稳定的，即一个相干的单色漂移波可以使一系列模式和相关的带状流变得不稳定。虽然最初增长最快的模式占主导，但随后的二次非线性不稳定性会以增长最快的调制不稳定模式两倍的增长率驱动最长波长的带状流及其相关边带。这导致从强不稳定的短波长模式直接转移到弱不稳定的长波长模式，从而消耗了短波长泵浦能量。一个相关但效率较低的直接涡量级联产生了位于调制不稳定模式带之外的极短波长模式。
