Simulated breaking of convectively generated mesoscale gravity waves and airglow modulation
Simulated breaking of convectively generated mesoscale gravity waves and airglow modulation
复制标题
DOI：
10.1016/j.jastp.2004.01.023
复制
发表时间：
2004-04
影响因子：
1.9
通讯作者：
T. Horinouchi
中科院分区：
文献类型：
--
作者：
T. Horinouchi
利用垂直扩展的中尺度气象模式进行了大量的数值模拟，研究了积云对流产生的大气重力波的破裂和破裂引起的中高层气辉调制。发现水平和垂直网格间距分别为1.5和0.5 km的模拟，如Horinouchi等人所述。Res. Lett. 29（21)(2002) 2007）可以粗略地模拟破裂，但更高的分辨率可以更好地阐明破裂和气辉调制的动力学。结果对亚网格尺度湍流闭包的敏感性也进行了研究。根据模拟结果，本文提出了一种近似的方法来估计OI5577原子氧气辉。正如预期的那样，我们发现，与波浪破裂相关的干扰会调制气辉，产生所谓的“波纹”型图案，由间距约10公里的条纹组成，这种图案经常出现在地面气辉成像中。通过高分辨率模拟，发现在某些断裂情况下，最初的不稳定扰动发展为剪切不稳定，产生波浪，引起明显的气辉波纹，尽管它们的条纹结构受到干扰。在这种情况下，传统的涡旋诊断表明，发达的湍流占主导地位。结果表明，一个显著的气辉调制可以在不稳定的后期发展，而没有考虑引起相干气辉调制。
A number of numerical simulations are conducted by using a vertically extended mesoscale meteorological model to study the breaking of atmospheric gravity waves generated by cumulus convection and the airglow modulation in the upper mesosphere induced by the breaking. It is found that a simulation with horizontal and vertical grid spacings of 1.5 and 0.5 km , as in Horinouchi et al. (Geophys. Res. Lett. 29(21) (2002) 2007), can crudely simulate the breaking, but the dynamics of the breaking and airglow modulation is better elucidated with a higher resolution. Sensitivity of the results to subgrid-scale turbulence closures is also examined. From the simulations, the OI5577 atomic oxygen airglow is estimated with an approximate method proposed in this study. It is found, as has been expected, that the disturbances associated with the wave breaking modulate the airglow to create the so-called “ripple”-type patterns consisting of stripes with a spacing of about 10 km , which are frequently found in ground-based airglow imaging. Using a high-resolution simulation, it is found that in some breaking cases the initial instability disturbance develops into shear instability creating billows that induce a conspicuous airglow ripple, although their stripe structure is disturbed. In such a case, conventional vortex diagnosis suggests the dominance of well-developed turbulence. The result indicates that a significant airglow modulation can develop at a late stage of instability that has not been considered to cause a coherent airglow modulation.