scholarly journals The effect of varying the source spectrum of a gravity wave parameterization in a middle atmosphere general circulation model

1998 ◽  
Vol 103 (D24) ◽  
pp. 31523-31539 ◽  
Author(s):  
E. Manzini ◽  
N. A. McFarlane
Keyword(s):  
Gravity Wave ◽  
General Circulation Model ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Source Spectrum ◽  
Atmosphere General Circulation Model

scholarly journals Southern Hemisphere Extratropical Gravity Wave Sources and Intermittency Revealed by a Middle-Atmosphere General Circulation Model

2016 ◽  
Vol 73 (3) ◽  
pp. 1335-1349 ◽  
Author(s):  
Simon P. Alexander ◽  
Kaoru Sato ◽  
Shingo Watanabe ◽  
Yoshio Kawatani ◽  
Damian J. Murphy
Keyword(s):  
Gravity Wave ◽  
Southern Hemisphere ◽  
General Circulation Model ◽  
Gravity Waves ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Absolute Gravity ◽  
Atmosphere General Circulation Model ◽  
Time Of Year

Abstract Southern Hemisphere extratropical gravity wave activity is examined using simulations from a free-running middle-atmosphere general circulation model called Kanto that contains no gravity wave parameterizations. The total absolute gravity wave momentum flux (MF) and its intermittency, diagnosed by the Gini coefficient, are examined during January and July. The MF and intermittency results calculated from the Kanto model agree well with results from satellite limb and superpressure balloon observations. The analysis of the Kanto model simulations indicates the following results. Nonorographic gravity waves are generated in Kanto in the frontal regions of extratropical depressions and around tropopause-level jets. Regions with lower (higher) intermittency in the July midstratosphere become more (less) intermittent by the mesosphere as a result of lower-level wave removal. The gravity wave intermittency is low and nearly homogeneous throughout the SH middle atmosphere during January. This indicates that nonorographic waves dominate at this time of year, with sources including continental convection as well as oceanic depressions. Most of the zonal-mean MF at 40°–65°S in January and July is due to gravity waves located above the oceans. The zonal-mean MF at lower latitudes in both months has a larger contribution from the land regions but the fraction above the oceans remains larger.

scholarly journals Gravity Wave Characteristics in the Southern Hemisphere Revealed by a High-Resolution Middle-Atmosphere General Circulation Model

2012 ◽  
Vol 69 (4) ◽  
pp. 1378-1396 ◽  
Author(s):  
Kaoru Sato ◽  
Satoshi Tateno ◽  
Shingo Watanabe ◽  
Yoshio Kawatani
Keyword(s):  
Gravity Wave ◽  
Energy Flux ◽  
Gravity Waves ◽  
Wave Energy ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Polar Vortex ◽  
Circulation Model ◽  
Southern Andes ◽  
Atmosphere General Circulation Model

Abstract Gravity wave characteristics in the middle- to high-latitude Southern Hemisphere are analyzed using simulation data over 3 yr from a high-resolution middle-atmosphere general circulation model without using any gravity wave parameterizations. Gravity waves have large amplitudes in winter and are mainly distributed in the region surrounding the polar vortex in the middle and upper stratosphere, while the gravity wave energy is generally weak in summer. The wave energy distribution in winter is not zonally uniform, but it is large leeward of the southern Andes and Antarctic Peninsula. Linear theory in the three-dimensional framework indicates that orographic gravity waves are advected leeward significantly by the mean wind component perpendicular to the wavenumber vector. Results of ray-tracing and cross-correlation analyses are consistent with this theoretical expectation. The leeward energy propagation extends to several thousand kilometers, which explains part of the gravity wave distribution around the polar vortex in winter. This result indicates that orographic gravity waves can affect the mean winds at horizontal locations that are far distant from the source mountains. Another interesting feature is a significant downward energy flux in winter, which is observed in the lower stratosphere to the south of the southern Andes. The frequency of the downward energy flux is positively correlated with the gravity wave energy over the southern Andes. Partial reflection from a rapid increase in static stability around 10 hPa and/or gravity wave generation through nonlinear processes are possible mechanisms to explain the downward energy flux.

scholarly journals Global Atmospheric Model Simulates Fine Details of Gravity Waves

Eos ◽  
2015 ◽  
Vol 96 ◽  
Author(s):  
Puneet Kollipara
Keyword(s):  
Gravity Wave ◽  
General Circulation Model ◽  
Gravity Waves ◽  
General Circulation ◽  
Circulation Model ◽  
Atmospheric Model ◽  
Global Atmospheric Model ◽  
Atmosphere General Circulation Model

Whole-atmosphere general circulation model captures many aspects of mesoscale gravity wave structures—down to the tens of kilometers—and resulting temperatures and tides.

Turbulent parameters in the middle atmosphere: Theoretical estimates deduced from a gravity-wave resolving general circulation model

2021 ◽  
Keyword(s):  
Gravity Wave ◽  
General Circulation Model ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Small Scale ◽  
Scaling Analysis ◽  
Stratified Turbulence ◽  
Atmospheric Flow ◽  
Diffusion Scheme

Abstract We present a scaling analysis for the stratified turbulent and small-scale turbulent regimes of atmospheric flow with emphasis on the mesosphere. We distinguish rotating-stratified macroturbulence turbulence (SMT), stratified turbulence (ST), and small-scale isotropic Kolmogorov turbulence (KT), and we specify the length and time scales and the characteristic velocities for these regimes. It is shown that the buoyancy scale (Lb) and the Ozmidov scale (Lo) are the main parameters that describe the transition from SMT to KT. We employ the buoyancy Reynolds number and horizontal Froude number to characterize ST and KT in the mesosphere. This theory is applied to simulation results from a high-resolution general circulation model with a Smagorinsky-type turbulent diffusion scheme for the sub-grid scale parameterization. The model allows us to derive the turbulent root-mean-square (RMS) velocity in the KT regime. It is found that the turbulent RMS velocity has a single maximum in summer and a double maximum in winter months. The secondary maximum in the winter MLT we associate with a secondary gravity wave breaking phenomenon. The turbulent RMS velocity results from the model agree well with Full Correlation Analyses based on MF-radar measurements. A new scaling for the mesoscale horizontal velocity based on the idea of direct energy cascade in masoscales is proposed. The latter findings for mesoscale and small-scale characteristic velocities supports the idea proposed in this research that mesoscale and small-scale dynamics in the mesosphere are governed by SMT, ST, and KT in the statistical average.

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