Details

Autor(en) / Beteiligte

• Sugimoto, Norihiko
• Takagi, Masahiro
• Matsuda, Yoshihisa

Titel

Fully Developed Superrotation Driven by the Mean Meridional Circulation in a Venus GCM

Ist Teil von

• Geophysical research letters, 2019-02, Vol.46 (3), p.1776-1784

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Fully developed superrotation is reproduced for the first time in very long term simulations with a dynamical Venus general circulation model (GCM) driven by a zonally averaged component of the realistic solar heating only. Starting from a motionless state with temperature distribution including a low static stability layer in the lower cloud layer, the fast superrotating zonal flow of ~100 m/s is established after 500 Earth years. In this experiment, the mean meridional circulation is responsible for generating the superrotation, because effects of thermal tides, topography, radiation process, and cloud physics are excluded in the present simulations. Sensitivity experiments indicate that the vertical eddy viscosity smaller than 0.02 m2/s is necessary for the fast superrotation to appear. The low static stability layer also strongly affects the superrotation with high‐latitude jets through angular momentum transport by baroclinic/barotropic instability in the cloud layer. Plain Language Summary The generation mechanism of the atmospheric superrotation on Venus is one of the most important topics in the Earth and planetary sciences. Here we reproduced the fully developed superrotation for the first time in a Venus general circulation model (GCM) driven by a zonally averaged component of the realistic solar heating only. Our GCM enables us to perform long‐term simulations with medium resolution higher than those used in previous studies. It is newly found that mean meridional circulation driven by the realistic solar heating can generate the fully developed superrotation of ~100 m/s with the vertical eddy viscosity smaller than 0.02 m2/s. It is also elucidated that a weakly stratified layer observed in the cloud layer, but neglected in previous GCMs, also strongly affects the superrotation with high‐latitude jets through angular momentum transport by baroclinic/barotropic instability. Existence of the range of the vertical eddy viscosity in which the fast superrotation can be generated by the reasonable solar heating has broad implications for the atmospheric sciences in light of optimal parameters for the GCMs. The present results are of fundamental importance in the Earth and planetary sciences to understand the variety of general circulation of the planetary atmospheres. Key Points Superrotation is generated from a motionless state by the mean meridional circulation mechanism Smallness of the vertical eddy viscosity is a key for the mean meridional circulation mechanism to generate fast superrotation Baroclinic/Barotropic instability in the low static stability layer plays an important role on the structure of superrotation