Baroclinic instability in the Venus atmosphere simulated by GCM

Norihiko Sugimoto, Masahiro Takagi, Yoshihisa Matsuda

研究成果: Article

18 引用 (Scopus)

抄録

Baroclinic instability in the super-rotation of Venus is investigated by a newly developed atmospheric general circulation model. First, we adopt an idealized super-rotation, i.e., solid-body rotating flow in a weakly stratified layer at cloud level, as an initial basic state in a nominal case. With the evolution of time, baroclinic instability occurs in a weakly stratified layer with large vertical shear of the basic zonal flow. Horizontal wind associated with the baroclinic instability modes is of a few ms-1. The initial structure of the unstable modes is similar to those obtained in previous linear stability analyses. However, it is modified by nonlinear interactions in the later stage, reaching a quasi-steady state. Meridional transport of momentum and heat by these unstable modes accelerates the super-rotation by ~ 0.05ms-1day-1 at midlatitudes. Furthermore, the dependence of baroclinic instability on the basic state, i.e., the meridional profiles of zonal flow and the vertical profiles of static stability, are subsequently investigated. For the super-rotation with midlatitude jets at cloud level, the modes are modified from baroclinic to barotropic in the later stage. Typically, their horizontal wind is of O(10) m s-1. Their amplitude is maintained by energy conversion from zonal-mean available potential energy associated with the baroclinic basic state. In the case where static stability is smaller than that in the nominal case, the baroclinic modes transfer angular momentum from midlatitude to the equator near a 70km level and accelerate the super-rotation by more than 10ms-1 in the equatorial region. Key Points Baroclinic instability in Venus is investigated by GCM for the first timeBaroclinic instability is likely to occur in the Venus atmosphereBaroclinic instability contributes to general circulation of Venus

元の言語English
ページ(範囲)1950-1968
ページ数19
ジャーナルJournal of Geophysical Research E: Planets
119
発行部数8
DOI
出版物ステータスPublished - 2014

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superrotation
Venus atmosphere
baroclinic instability
Venus
Venus (planet)
general circulation model
temperate regions
atmosphere
static stability
zonal flow
strata
Atmospheric General Circulation Models
rotating flow
rotating bodies
baroclinic mode
equatorial regions
quasi-steady states
atmospheric general circulation model
energy conversion
equators

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

これを引用

Baroclinic instability in the Venus atmosphere simulated by GCM. / Sugimoto, Norihiko; Takagi, Masahiro; Matsuda, Yoshihisa.

:: Journal of Geophysical Research E: Planets, 巻 119, 番号 8, 2014, p. 1950-1968.

研究成果: Article

Sugimoto, Norihiko ; Takagi, Masahiro ; Matsuda, Yoshihisa. / Baroclinic instability in the Venus atmosphere simulated by GCM. :: Journal of Geophysical Research E: Planets. 2014 ; 巻 119, 番号 8. pp. 1950-1968.
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AB - Baroclinic instability in the super-rotation of Venus is investigated by a newly developed atmospheric general circulation model. First, we adopt an idealized super-rotation, i.e., solid-body rotating flow in a weakly stratified layer at cloud level, as an initial basic state in a nominal case. With the evolution of time, baroclinic instability occurs in a weakly stratified layer with large vertical shear of the basic zonal flow. Horizontal wind associated with the baroclinic instability modes is of a few ms-1. The initial structure of the unstable modes is similar to those obtained in previous linear stability analyses. However, it is modified by nonlinear interactions in the later stage, reaching a quasi-steady state. Meridional transport of momentum and heat by these unstable modes accelerates the super-rotation by ~ 0.05ms-1day-1 at midlatitudes. Furthermore, the dependence of baroclinic instability on the basic state, i.e., the meridional profiles of zonal flow and the vertical profiles of static stability, are subsequently investigated. For the super-rotation with midlatitude jets at cloud level, the modes are modified from baroclinic to barotropic in the later stage. Typically, their horizontal wind is of O(10) m s-1. Their amplitude is maintained by energy conversion from zonal-mean available potential energy associated with the baroclinic basic state. In the case where static stability is smaller than that in the nominal case, the baroclinic modes transfer angular momentum from midlatitude to the equator near a 70km level and accelerate the super-rotation by more than 10ms-1 in the equatorial region. Key Points Baroclinic instability in Venus is investigated by GCM for the first timeBaroclinic instability is likely to occur in the Venus atmosphereBaroclinic instability contributes to general circulation of Venus

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