Cyclone–anticyclone asymmetry in gravity wave radiation from a co-rotating vortex pair in rotating shallow water
Cyclone–anticyclone asymmetry in gravity wave radiation from a co-rotating vortex pair in rotating shallow water
复制标题
旋转浅水中同向旋转涡对重力波辐射的旋风-反气旋不对称性
DOI：
10.1017/jfm.2015.209
复制
发表时间：
2015
影响因子：
3.7
通讯作者：
Yutaka Shimomura
中科院分区：
文献类型：
--
作者：
N. Sugimoto;K. Ishioka;Hiromichi Kobayashi;Yutaka Shimomura
本文研究了平面浅水系统中同向旋转涡旋对自发重力波辐射的气旋-反气旋不对称性。通过与航空声学声波辐射理论（莱特希尔理论）类比，解析地导出了重力波的远场。在导出的形式中，地球的自转不仅影响重力波的传播，而且影响它们的来源。虽然结果符合理论的涡声在限制的$f\rightarrow 0$，有一个不对称的重力波辐射的气旋对和反气旋对之间的有限值的$f$。由于地球自转的影响，反气旋对辐射的重力波比气旋对更强烈。此外，在中等f时，反气旋对产生的重力波强度有局部极大值。为了验证解析解，数值模拟也进行了一个新开发的谱方法在无界区域。该方法的新奇在于，由于保角映射和伪高粘性，在波的远场中起海绵层的作用，因此在边界处不存在波反射。数值计算结果与分析结果吻合得很好，即使对于有限值的f$的气旋对和反气旋对。
Cyclone–anticyclone asymmetry in spontaneous gravity wave radiation from a co-rotating vortex pair is investigated in an $f$ -plane shallow water system. The far field of gravity waves is derived analytically by analogy with the theory of aeroacoustic sound wave radiation (Lighthill theory). In the derived form, the Earth’s rotation affects not only the propagation of gravity waves but also their source. While the results correspond to the theory of vortex sound in the limit of $f\rightarrow 0$ , there is an asymmetry in gravity wave radiation between cyclone pairs and anticyclone pairs for finite values of $f$ . Anticyclone pairs radiate gravity waves more intensely than cyclone pairs due to the effect of the Earth’s rotation. In addition, there is a local maximum of intensity of gravity waves from anticyclone pairs at an intermediate $f$ . To verify the analytical solution, a numerical simulation is also performed with a newly developed spectral method in an unbounded domain. The novelty of this method is the absence of wave reflection at the boundary due to a conformal mapping and a pseudo-hyperviscosity that acts like a sponge layer in the far field of waves. The numerical results are in excellent agreement with the analytical results even for finite values of $f$ for both cyclone pairs and anticyclone pairs.