[A-CG40] Dynamics of Oceanic and Atmospheric Waves, Vortices, and Circulations

[ACG40-P02] Dependency on the horizontal diffusion of the super-rotation reproduced in a Venus GCM

*Norihiko Sugimoto¹, Yukiko Fujisawa², Nobumasa Komori², Hiroki Kashimura³, Masahiro Takagi⁴, Yoshihisa Matsuda⁵ (1.Keio University, Department of Physics, 2.Keio University, Research and Education Center for Natural Sciences, 3.Kobe University, Graduate School of Science, 4.Kyoto Sangyo University, Faculty of Science, 5.Tokyo Gakugei University, Department of Astronomy and Earth Science)

Keywords:Venus atmosphere, Super rotation, General circulation model, Horizontal diffusion

Horizontal diffusion and resolution are important factors to generate and maintain the super-rotation in the general circulation model (GCM) because waves which transport angular momentum are sensitive to them. Here, we investigated how the super-rotation depends on the magnitude of horizontal hyper diffusion using a Venus atmospheric GCM with medium and high resolutions. In both the runs, we found a parameter range where the structure of fully developed super-rotation is almost independent of the magnitude of horizontal diffusion. Spectral analysis shows that unrealistically strong super-rotation is developed when medium-scale disturbances are dissipated by stronger horizontal diffusion. On the other hand, artificially weak super-rotation is also realized because spurious small-scale disturbances are accumulated when the horizontal diffusion is too weak.