Angular distribution of energy spectrum in two-dimensional β-plane turbulence in the long-wave limit

• 齋藤, 泉

• Ishioka, Keiichi

抄録

The time-evolution of two-dimensional decaying turbulence governed by the long-wave limit, in which L_{D}IL → 0, of the quasi-geostrophic equation is investigated numerically. Here, LD is the Rossby radius of deformation, and L is the characteristic length scale of the flow. In this system, the ratio of the linear term that originates from the β-term to the nonlinear terms is estimated by a dimensionless number, γ = βL_{D}^{2}IU, where β is the latitudinal gradient of the Coriolis parameter, and U is the characteristic velocity scale. As the value of γ increases, the inverse energy cascade becomes more anisotropic. When γ ⩾ 1, the anisotropy becomes significant and energy accumulates in a wedge-shaped region where |I|>{√3}|k| in the two-dimensional wavenumber space. Here, k and I are the longitudinal and latitudinal wavenumbers, respectively. When γ is increased further, the energy concentration on the lines of I = ±{√3}K is clearly observed. These results are interpreted based on the conservation of zonostrophy, which is an extra invariant other than energy and enstrophy and was determined in a previous study. Considerations concerning the appropriate form of zonostrophy for the long-wave limit and a discussion of the possible relevance to Rossby waves in the ocean are also presented.

収録刊行物

• Physics of Fluids

  Physics of Fluids 25 (7), 2013-07-18

  AIP Publishing LLC

キーワード

• Coriolis force
• numerical analysis
• ocean waves
• Rossby waves
• turbulence, vortices

詳細情報

• CRID: 1050282810754516352
• NII論文ID: 120005323020
• NII書誌ID: AA10986202
• ISSN: 10706631
• HANDLE: 2433/178670
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles