Superrotation of Venus' atmosphere analyzed with a full general circulation model
Superrotation of Venus' atmosphere analyzed with a full general circulation model
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DOI：
10.1029/2009je003458
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发表时间：
2010-06-12
影响因子：
4.8
通讯作者：
Forget, Francois
中科院分区：
文献类型：
--
作者：
Lebonnois, Sebastien;Hourdin, Frederic;Forget, Francois
在我们实验室为地球开发的大气环流模式的基础上，为金星大气开发了一个从地表到100公里高度的大气环流模式。这个新的GCM的主要特点包括地形，昼夜循环，比热对温度的依赖性，以及一致的辐射传输模块的基础上净交换率矩阵。这使得一致的温度场的计算，与以前的金星大气GCM使用简化的温度强迫。在350个金星日（111个地球年）后分析环流。在大约40公里的高度以上可以获得超自转。下面，纬向风与观测值相比仍然很小，这是一个悬而未决的问题。纬向环流由赤道到极点的环流组成，其中占主导地位的环流位于云层内。模拟的温度结构与观测结果在全球范围内是一致的，尽管在最低层的稳定性和云内的赤道-极点温度对比方面存在差异（与观测到的40 K相比，模型中的10 K）。与观测数据一致，在云层底部（约47公里）和云层中部（55-60公里高度）之间发现了对流层。角动量的传输进行了分析，和参考模拟和模拟之间的比较，没有周日周期说明热潮汐在赤道地区所发挥的作用。在没有日周期的情况下，Gierasch-Rossow-威廉姆斯机制控制角动量输送。在赤道地区，昼夜潮汐增加了显著的动量向下输送，导致低纬动量积累。
A general circulation model (GCM) has been developed for the Venus atmosphere, from the surface up to 100 km altitude, based on the GCM developed for Earth at our laboratory. Key features of this new GCM include topography, diurnal cycle, dependence of the specific heat on temperature, and a consistent radiative transfer module based on net exchange rate matrices. This allows a consistent computation of the temperature field, in contrast to previous GCMs of Venus atmosphere that used simplified temperature forcing. The circulation is analyzed after 350 Venus days (111 Earth years). Superrotation is obtained above roughly 40 km altitude. Below, the zonal wind remains very small compared to observed values, which is a major pending question. The meridional circulation consists of equator-to-pole cells, the dominant one being located within the cloud layers. The modeled temperature structure is globally consistent with observations, though discrepancies persist in the stability of the lowest layers and equator-pole temperature contrast within the clouds (10 K in the model compared to the observed 40 K). In agreement with observational data, a convective layer is found between the base of the clouds (around 47 km) and the middle of the clouds (55-60 km altitude). The transport of angular momentum is analyzed, and comparison between the reference simulation and a simulation without diurnal cycle illustrates the role played by thermal tides in the equatorial region. Without diurnal cycle, the Gierasch-Rossow-Williams mechanism controls angular momentum transport. The diurnal tides add a significant downward transport of momentum in the equatorial region, causing low latitude momentum accumulation.