Geostrophic dynamics in the horizontally differential super-rotation of Venus are examined using fA (the Coriolis parameter defined by the angular velocity of a basic flow in an inertial frame) and Γ (the differential rotation parameter defined by the latitudinal gradient of the angular velocity) under the conditions that vertical shear of the basic field is not considered and the intrinsic phase velocity has a magnitude comparable to that of an eddy horizontal flow. The geostrophic and quasi-geostrophic approximations are valid in the regions of weakly differential and rigid-body super-rotations; however, they are invalid in the regions of strongly differential super-rotation even when the Rossby number RO is sufficiently smaller than unity for synoptic eddies. In a general circulation model of a Venus-like atmosphere, the horizontal divergence that results from the strong differential cannot be ignored over a wide range within latitudes ±60° and below 60 km elevation because of large Γ/fA(≥1/2).
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Astronomy and Astrophysics
- Mechanics of Materials
- Geochemistry and Petrology