Venusian middle-atmospheric dynamics in the presence of a strong plan etary-scale 5.5-day wave
Venusian middle-atmospheric dynamics in the presence of a strong plan etary-scale 5.5-day wave
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存在强大的行星尺度 5.5 天波时的金星中层大气动力学
DOI：
10.1016/j.icarus.2011.06.017
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发表时间：
2012
期刊：
影响因子：
3.2
通讯作者：
M.Takahashi
中科院分区：
文献类型：
--
作者：
Yamamoto;M.;M.Takahashi
本文用一个中层大气环流模式研究了金星中层大气动力学。超旋转的大小对行星尺度波的振幅很敏感。特别是强迫行星尺度波的临界水平扰动可能有助于维持云底附近的超旋转。在强5.5天波强迫的情况下，纬向风速大于100 ms − 1的超旋转由强迫波维持。在赤道云顶和云底附近分别有4天和5.5天的波动。行星尺度的波有一个Y形图案的存在下，强烈的热潮汐的振幅调制。在该模式中，极热偶极子在云顶附近是不稳定的，动力学行为复杂。当高纬向波数的辐散涡在热偶极子区占主导地位时，偶极子合并成偶极子或分裂成三极。一个冷领部分地增强了纬向波数为1的缓慢传播波的冷相。虽然这样一个复杂的偶极子行为还没有被观察到，它很可能发生在一个类似于本模拟的动力学条件下。因此，使用大气环流模式的动力学方法可能有助于分析金星快车和地面观测数据。
The middle atmospheric dynamics on Venus are investigated using a middle atmosphere general circulation model. The magnitude of the superrotation is sensitive to the amplitude of the planetary-scale waves. In particular, the critical level absorptions of the forced planetary-scale waves might contribute to the maintenance of the superrotation near the cloud base. In the case of strong 5.5-day wave forcing, the superrotation with zonal wind speed higher than 100ms−1is maintained by the forced wave. Four-day and 5.5-day waves are found near the equatorial cloud top and base, respectively. The planetary-scale waves have a Y-shaped pattern maintained by the amplitude modulation in the presence of strong thermal tides. The polar hot dipole is unstable and its dynamical behavior is complex near the cloud top in this model. The dipole merges into a monopole or breaks up into a tripole when the divergent eddies with high zonal wavenumbers are predominant in the hot dipole region. A cold collar is partly enhanced by a cold phase of slowly propagating waves with zonal wavenumber 1. Although such a complex dipole behavior has not been observed yet, it is likely to occur under a dynamical condition similar to the present simulation. Thus, the dynamical approach using a general circulation model might be useful for analyzing Venus Express and ground-based observation data.