Vertical momentum transports associated with moist convection and gravity waves in a minimal model of QBO-like oscillation

• 西本, 絵梨子

• 余田, 成男

• Bui, Hoang Hai

抄録

A self-sustained oscillation dynamically analogous to the equatorial quasi-biennial oscillation (QBO) was obtained as a radiative-moist-convective quasi-equilibrium state in a minimal model of the stratosphere- troposphere coupled system, which is a two-dimensional cloud-system-resolving nonhydrostatic model with a periodic lateral boundary condition. The QBO-like oscillation shows downward propagation of the zonalmean signals in the stratosphere. In addition, in the troposphere there are periodic variations associated with the QBO-like oscillation, including organized features of moist-convective systems characterized as squall-line- or back-building-type precipitation patterns.Details of themomentumbudget variation are examined to study the stratosphere-troposphere dynamical coupling associated with the QBO-like oscillation. The vertical flux of horizontal momentum is separated into three contributions of convective momentum transport (CMT) and momentum transports by upward- and downward-propagating gravity waves-that is, upward and downward gravity wave momentum transports (GWMTs)-and the time-height variations of each contribution are evaluated quantitatively. The method is based on the linear theory of gravity waves to separate upward- and non-upward-propagating contributions and uses the phase speed spectra of the total cloud mixing ratio to identify the CMT contribution. The upward GWMT predominates in the stratosphere and contributes to the acceleration of the zonal mean zonal wind. The CMT and downward GWMT are confined to the troposphere, and the former predominates. The variations of the mean zonal wind modulate the organization of convective systems, and the squall-line- and back-building-type patterns appear alternately. According to the modulation of convective systems, the spectral features of every momentum transport vary periodically.

収録刊行物

• Journal of the Atmospheric Sciences

  Journal of the Atmospheric Sciences 73 2935-2957, 2016-07-01

  American Meteorological Society

キーワード

• Geographic location/entity
• Tropics
• Circulation/ Dynamics
• Convective clouds
• Gravity waves
• Quasibiennial oscillation
• Physical Meteorology and Climatology
• Momentum
• Models and modeling
• Cloud resolving models

詳細情報

• CRID: 1050001335843666048
• NII論文ID: 120006027137
• ISSN: 15200469
• ISSN: 00224928
• DOI: 10.1175/jas-d-15-0265.1
• HANDLE: 2433/219483
• Web Site: http://journals.ametsoc.org/jas/article-pdf/73/7/2935/3662405/jas-d-15-0265_1.pdf
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
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  • Crossref
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