Quasi two-day-wave modulation of gravity wave flux and consequences for the planetary wave propagation in a simple circulation model

Abstract. The high-frequency and small horizontal scale gravity waves may be reflected and ducted in non-hydrostatic simulations, but usually propagate vertically in hydrostatic models. To examine gravity wave propagation, a preliminary study has been conducted with a global ionosphere–thermosphere model (GITM), which is a non-hydrostatic general circulation model for the upper atmosphere. GITM has been run regionally with a horizontal resolution of 0.2° long × 0.2° lat to resolve the gravity wave with wavelength of 250 km. A cosine wave oscillation with amplitude of 30 m s−1 has been applied to the zonal wind at the low boundary, and both high-frequency and low-frequency waves have been tested. In the high-frequency case, the gravity wave stays below 200 km, which indicates that the wave is reflected or ducted in propagation. The results are consistent with the theoretical analysis from the dispersion relationship when the wavelength is larger than the cutoff wavelength for the non-hydrostatic situation. However, the low-frequency wave propagates to the high altitudes during the whole simulation period, and the amplitude increases with height. This study shows that the non-hydrostatic model successfully reproduces the high-frequency gravity wave dissipation.

Download Full-text

Long Extratropical Planetary Wave Propagation in the Presence of Slowly Varying Mean Flow and Bottom Topography. Part I: The Local Problem

Journal of Physical Oceanography ◽

10.1175/1520-0485(2003)33<784:lepwpi>2.0.co;2 ◽

2003 ◽

Vol 33 (4) ◽

pp. 784-801 ◽

Cited By ~ 56

Author(s):

Peter D. Killworth ◽

Jeffrey R. Blundell

Keyword(s):

Wave Propagation ◽

Planetary Wave ◽

Bottom Topography ◽

Local Problem ◽

Mean Flow ◽

Planetary Wave Propagation

Download Full-text

Stationary planetary wave propagation in Northern Hemisphere winter – climatological analysis of the refractive index

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-183-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 183-200 ◽

Cited By ~ 36

Author(s):

Q. Li ◽

H.-F. Graf ◽

M. A. Giorgetta

Keyword(s):

Refractive Index ◽

Wave Propagation ◽

Northern Hemisphere ◽

Planetary Wave ◽

Planetary Waves ◽

Mean Flow ◽

Stratospheric Circulation ◽

Hemisphere Winter ◽

Planetary Wave Propagation ◽

Northern Hemisphere Winter

Abstract. The probability density on a height-meridional plane of negative refractive index squared f(nk2<0) is introduced as a new analysis tool to investigate the climatology of the propagation conditions of stationary planetary waves based on NCEP/NCAR reanalysis data for 44 Northern Hemisphere boreal winters (1958–2002). This analysis addresses the control of the atmospheric state on planetary wave propagation. It is found that not only the variability of atmospheric stability with altitudes, but also the variability with latitudes has significant influence on planetary wave propagation. Eliassen-Palm flux and divergence are also analyzed to investigate the eddy activities and forcing on zonal mean flow. Only the ultra-long planetary waves with zonal wave number 1, 2 and 3 are investigated. In Northern Hemisphere winter the atmosphere shows a large possibility for stationary planetary waves to propagate from the troposphere to the stratosphere. On the other hand, waves induce eddy momentum flux in the subtropical troposphere and eddy heat flux in the subpolar stratosphere. Waves also exert eddy momentum forcing on the mean flow in the troposphere and stratosphere at middle and high latitudes. A similar analysis is also performed for stratospheric strong and weak polar vortex regimes, respectively. Anomalies of stratospheric circulation affect planetary wave propagation and waves also play an important role in constructing and maintaining of interannual variations of stratospheric circulation.

Download Full-text