A contribution to the baroclinic instability problem
A contribution to the baroclinic instability problem
复制标题
对斜压不稳定问题的贡献
DOI：
10.3402/tellusa.v22i3.10219
复制
发表时间：
1970
期刊：
影响因子：
2
通讯作者：
R. Norscini
中科院分区：
文献类型：
--
作者：
R. V. Garcia;R. Norscini
在类似于绿色模式的假设下，提出了纬向气流斜压不稳定性问题。该模型的动力学方程导致一个单一的微分方程的垂直速度，这是合流超几何类型。特征值问题的解决和数值方法只用于寻找根的特征方程。结果表明，对于大值的无量纲剪切？（与绿色参数有关的是什么？= 2个？? 1），从快速增长的不稳定模式到小增长率的不稳定模式有一个连续的过渡。该模型的特征方程的本征值并不象绿色（1960）和广田（1968）的数值计算中所出现的那样，表现出从共轭复根到真实的根的连续过渡。另一方面，对于较小的剪切值，可以发生从不稳定到稳定解的连续过渡。在长波一侧的这样一个过渡点有弱的不稳定波，其操纵水平是外部的流;在短波一侧有一个轻微的差距，在频谱的不稳定波。本文讨论了波的结构，指出在靠近下边界的浅层中，增长率慢的不稳定波具有斜压不稳定波的结构。DOI：10.1111/j.2153-3490.1970.tb00493.x
The problem of the baroclinic instability of zonal flow is formulated under assumptions similar to Green's model. The dynamic equations of the model lead to a single differential equation for the vertical velocity, which is of the confluent hyper-geometric type. The eigen-value problem is solved and numerical methods are only used to find the roots of the characteristic equation. It is shown that, for large values of the nondimensional shear ? (which is related to Green's parameter ? = 2? ?1 ), there is a continuous transition from fast growing unstable modes to unstable modes with small growth-rate. The eigen-values of the characteristic equation of the model do not show the continuous transition from the conjugate complex roots to the real roots as appears in the numerical computations of Green (1960) and Hirota (1968). On the other hand, for smaller values of the shear, a continuous transition from the unstable to stable solutions can occur. On the long wave side of such a transition point there are weak unstable waves whose steering level is outside the flow; on the short wave side there is a slight gap in the spectrum of unstable waves. The structure of the waves is discussed and it is shown that the unstable waves with slow growth rate have the structure of a baroclinically unstable wave in a shallow layer close to the lower boundary. DOI: 10.1111/j.2153-3490.1970.tb00493.x