A further study of dynamics of the four-day circulation in the Venus atmosphere
A further study of dynamics of the four-day circulation in the Venus atmosphere
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金星大气四天环流动力学的进一步研究
DOI：
10.2151/jmsj1965.60.1_245
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发表时间：
1982
影响因子：
3.1
通讯作者：
Y. Matsuda
中科院分区：
文献类型：
--
作者：
Y. Matsuda
本文用五层模式的时间积分检验了Matsuda(1980)用双层模式建立的金星大气四天环流的定常模式。假定水平粘性为无穷大，结果表明，在1000d以上，由于角动量的积累，高层逐渐形成快速纬向流。角动量从一颗缓慢旋转的行星提供给低层大气，并通过经向环流向上输送。得到了三个外部参数(即水平扩散时间、纬向差热和行星自转速度)的不同值的定常解。当水平扩散时间(由垂直扩散时间归一化)8减小到10-2时，系统出现多个平衡态。当8降到10~(-3)时，在某些溶液中实现了与观测到的超自转速度一样大的超自转速度。本模型中(多)平衡态的参数依赖关系类似于Matsuda(1980)的两层模型所得到的结果。通过对两种模式所得到的平衡态的比较，验证了Matsuda(1980)对多重平衡态稳定性的预测：纬向气流较快的状态和经向环流较强的状态是稳定的，具有介于这两种状态之间的特征的状态是不稳定的。最后，通过假定两种不同的外部加热方式(突然加热和逐步加热)，验证了两种稳定状态中的哪一种为最终状态：突然加热导致经向环流较强的状态，而逐渐加热到纬向气流较快的状态。
A steady state model on the four-day circulation in the Venus atmosphere proposed by Matsuda (1980) with use of two-layer model is examined by time integrations of a fivelayer model. By assuming infinite horizontal viscosity, it is shown that the fast zonal flow is gradually formed in the upper layer over 1,000 days by the accumulation of angular momentum. This angular momentum is supplied to the lower atmosphere from a slowly rotating planet and is transported upward by meridional circulation. Stationary solutions are obtained for various values of three external parameters (i.e., horizontal diffusion time, latitudinal differential heating and planetary speed of rotation). Multiple equilibrium states appear in the system when the horizontal diffusion time (normalized by the vertical one) 8 is reduced to 10-2. The super-rotation rate as large as the observed one is realized in some solutions when 8 is reduced to 10-3. The parameter dependence of (multiple) equilibrium states in the present model is analogous to that obtained by the two-layer model in Matsuda (1980). By comparison between the equilibrium states obtained in these two models, the prediction on the stability of multiple equilibrium states (Matsuda (1980)) is verified; the state with the fast zonal flow and the state with the strong meridional cell are stable and the state having the characteristics intermediate between these two states is unstable. Finally, by assuming two different ways of external heating (sudden heating and gradual heating), it is examined which of the two stable states is attained as a final state; the sudden heating leads to the state with strong meridional cell, while the gradual heating to the state with fast zonal flow.