Geostrophic approximation in horizontally differential atmospheric rotation

Masaru Yamamoto, Hiroshi Tanaka

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Pages (from-to)273-279
Number of pages7
JournalTheoretical and Applied Mechanics Japan
Volume53
Publication statusPublished - Dec 1 2004

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Approximation
approximation
planetary atmospheres
stellar atmospheres
Angular velocity
angular velocity
Atmosphere
vortices
Froude number
Phase Velocity
Phase velocity
rigid structures
phase velocity
Rigid Body
Horizontal
Radius
Gradient
gradients
radii

All Science Journal Classification (ASJC) codes

  • Mathematics(all)
  • Condensed Matter Physics
  • Mechanics of Materials

Cite this

Geostrophic approximation in horizontally differential atmospheric rotation. / Yamamoto, Masaru; Tanaka, Hiroshi.

In: Theoretical and Applied Mechanics Japan, Vol. 53, 01.12.2004, p. 273-279.

Research output: Contribution to journalArticle

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