Effects of horizontally differential atmospheric rotation are considered in geostrophic dynamics of planetary and stellar atmospheres. The Coriolis parameter defined by the angular velocity of a basic flow f and the latitudinal gradient of the angular velocity Γ are used in the present study. Nondimensional differential rotation factor Γ/f and Rossby number R o determine whether the geostrophic approximation can be applied to differential rotations of planetary and stellar atmospheres, or not. When an eddy with small intrinsic phase velocity satisfies the condition of F r ≤ 1 (F r: Froude number) and L/a ≤ R o ≪ 1 (L: eddy horizontal scale, a: planetary radius), for rigid-body rotation (Γ/f ≪ R o 2 or Γ/f ∼ R o 2) and weakly differential rotation (Γ/f ∼ R o 1), the geostrophic approximation can be applied. However, for strongly differential rotation (Γ/f ∼ R o 0), the geostrophic approximation cannot be applied, even when R o is sufficiently small.
|Number of pages||7|
|Journal||Theoretical and Applied Mechanics Japan|
|Publication status||Published - Dec 1 2004|
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanics of Materials