Stratospheric inertia-gravity waves generated in a numerical model of frontogenesis. I: Model solutions

Morwenna Griffiths, Michael J. Reeder

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Abstract

The generation of stratospheric inertia-gravity waves is investigated with the aid of a dry two-dimensional anelastic numerical model. The model calculations follow the development of upper-level and low-level fronts together with their attendant jets. Long-wavelength low-frequency inertia-gravity waves are generated in the model runs. The key constituents of the model basic-state are: (1) a time-dependent shear flow normal to the front in thermal-wind balance with the along-front potential temperature; and (2) a time- and height-independent confluent-deformation wind-field with its axis of dilation parallel to the front. When the cross-front geostrophic wind shear △ is negative, and consequently the upper-level jet advects cold air along the upper front, prominent vertically propagating inertia-gravity waves are evident in the lower stratosphere. Like those observed in the atmosphere, the modelled waves have frequencies close to the inertial frequency, horizontal wavelengths of order 400-1200 km, and vertical wavelengths in the range 2-10 km. Numerical experiments in which △ ≥ 0 showed little gravity-wave activity.

Original languageEnglish
Pages (from-to)1153-1174
Number of pages22
JournalQuarterly Journal of the Royal Meteorological Society
Volume122
Issue number533
DOIs
Publication statusPublished - 1 Jan 1996

Keywords

  • Frontogenesis
  • Gravity-wave drag
  • Inertia-gravity waves
  • Jet streams
  • Stratosphere

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