The Instability of Medium-Scale Disturbances in a Moist Atmosphere
The Instability of Medium-Scale Disturbances in a Moist Atmosphere
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潮湿大气中中等规模扰动的不稳定性
DOI：
10.2151/jmsj1965.54.4_191
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
K. Gambo
中科院分区：
文献类型：
--
作者：
K. Gambo
将湿大气中尺度扰动的不稳定性与干燥大气中尺度扰动的特征相比较，讨论了中尺度扰动的不稳定性。在大气干燥的情况下，当Richardson数Ri为单位数量级时，中尺度扰动是较好的模式。在湿大气的情况下，我们假设凝结过程是由于常规斜压波的大尺度上升运动和(亚网格尺度)对流运动所致。本文对对流运动释放的潜热用所谓的CISK机制进行了处理。引入了表示行星边界层摩擦辐合引起的垂直p速度与常规斜压波垂直p速度之比的参数*。解析地讨论了中尺度扰动在**1和**1情形下的不稳定性。结果表明，在**1处的不稳定扰动对应于修正的传统斜压不稳定波。而**1处的不稳定扰动则表现出不同的特征，即在西风带上没有转向层，槽轴向东倾斜。还讨论了当Ri*0(1)和**1时，沿子午线方向的Rossby数Ry对增长率的影响。
The instability of medium-scale disturbances in a moist atmosphere is discussed comparing with the characteristics of medium-scale disturbances in a dry atmosphere. In case of a dry atmosphere, the prefered mode of medium-scale disturbances is expected when the Richardson number Ri is of the order of unity. In case of a moist atmosphere, we assume the condensation processes due to the large-scale upward motion of the conventional baroclinic wave and also due to the (sub-grid scale) convective motion. In this paper, the released latent heat of convective motion is treated in a way of the so-called CISK mechanism. The parameter * which represents the ratio of the vertical p-velocity due to the frictional convergence in the planetary boundary layer to that of the conventional baroclinic wave is introduced. The instability of medium-scale disturbances is discussed analytically in cases where ** 1 and ** 1. It is shown that the unstable disturbance where **1 corresponds to the modified conventional baroclinic unstable wave. However, the unstable disturbance where ** 1 shows the different characteristics in a sense that there is no steering-level and the trough axis tilts eastward in the westerlies. The role of the Rossby number in the meridional direction, Ry on the growth rate is also discussed when Ri * 0 (1) and * *1.