scholarly journals Planetary wave characteristics of gravity wave modulation from 30–130 km

2012 ◽  
Vol 10 ◽  
pp. 271-277 ◽  
Author(s):  
P. Hoffmann ◽  
Ch. Jacobi
Keyword(s):  
Planetary Wave ◽  
Middle Atmosphere ◽  
Model Simulation ◽  
Phase Speed ◽  
Circulation Model ◽  
Wave Characteristics ◽  
F Region ◽  
Zonal Wavenumber ◽  
Momentum Fluxes ◽  
High Phase

Abstract. Fast gravity waves (GW) have an important impact on the momentum transfer between the middle and upper atmosphere. Experiments with a circulation model indicate a penetration of high phase speed GW into the thermosphere as well as an indirect propagation of planetary waves by the modulation GW of momentum fluxes into the thermosphere. Planetary wave characteristics derived from middle atmosphere SABER temperatures, GW potential energy and ionospheric GPS-TEC data at midlatitudes reveal a possible correspondence of PW signatures in the middle atmosphere and ionosphere in winter around solar maximum (2002–2005). In the case of the westward propagating 16-day wave with zonal wavenumber 1 a possible connection could be found in data analysis (November–December 2003) and model simulation. Accordingly, GW with high phase speeds might play an essential role in the transfer of PW and other meteorological disturbances up to the ionospheric F-region.

scholarly journals The Antarctic Oscillation Structure in an AOGCM with Interactive Stratospheric Ozone

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
S. Brand ◽  
K. Dethloff ◽  
D. Handorf
Keyword(s):  
General Circulation ◽  
Planetary Wave ◽  
Middle Atmosphere ◽  
Stratospheric Ozone ◽  
Circulation Model ◽  
Wave Activity ◽  
Antarctic Oscillation ◽  
Wave Dynamics ◽  
Hemisphere Winter ◽  
The Antarctic

Based on 150-year equilibrium simulations using the atmosphere-ocean-sea ice general circulation model (AOGCM) ECHO-GiSP, the southern hemisphere winter circulation is examined focusing on tropo-stratosphere coupling and wave dynamics. The model covers the troposphere and strato-mesosphere up to 80 km height and includes an interactive stratospheric chemistry. Compared to the reference simulation without interactive chemistry, the interactive simulation shows a weaker polar vortex in the middle atmosphere and is shifted towards the negative phase of the Antarctic Oscillation (AAO) in the troposphere. Differing from the northern hemisphere winter situation, the tropospheric planetary wave activity is weakened. A detailed analysis shows, that the modelled AAO zonal mean signal behaves antisymmetrically between troposphere and strato-mesosphere. This conclusion is supported by reanalysis data and a discussion of planetary wave dynamics in terms of Eliassen-Palm fluxes. Thereby, the tropospheric planetary wave activity appears to be controlled from the middle atmosphere.

scholarly journals Local Dynamics of Baroclinic Waves in the Martian Atmosphere

2013 ◽  
Vol 70 (11) ◽  
pp. 3415-3447 ◽  
Author(s):  
Michael J. Kavulich ◽  
Istvan Szunyogh ◽  
Gyorgyi Gyarmati ◽  
R. John Wilson
Keyword(s):  
General Circulation ◽  
Baroclinic Instability ◽  
Phase Speed ◽  
Circulation Model ◽  
Regular Structure ◽  
Martian Atmosphere ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Global Features ◽  
Baroclinic Waves ◽  
Zonal Wavenumber

Abstract The paper investigates the processes that drive the spatiotemporal evolution of baroclinic transient waves in the Martian atmosphere by a simulation experiment with the Geophysical Fluid Dynamics Laboratory (GFDL) Mars general circulation model (GCM). The main diagnostic tool of the study is the (local) eddy kinetic energy equation. Results are shown for a prewinter season of the Northern Hemisphere, in which a deep baroclinic wave of zonal wavenumber 2 circles the planet at an eastward phase speed of about 70° Sol−1 (Sol is a Martian day). The regular structure of the wave gives the impression that the classical models of baroclinic instability, which describe the underlying process by a temporally unstable global wave (e.g., Eady model and Charney model), may have a direct relevance for the description of the Martian baroclinic waves. The results of the diagnostic calculations show, however, that while the Martian waves remain zonally global features at all times, there are large spatiotemporal changes in their amplitude. The most intense episodes of baroclinic energy conversion, which take place in the two great plain regions (Acidalia Planitia and Utopia Planitia), are strongly localized in both space and time. In addition, similar to the situation for terrestrial baroclinic waves, geopotential flux convergence plays an important role in the dynamics of the downstream-propagating unstable waves.

scholarly journals Influence of the sudden stratosphere warming on quasi-2 day waves

2016 ◽  
Author(s):  
Sheng-Yang Gu ◽  
Han-Li Liu ◽  
Xiankang Dou ◽  
Tao Li
Keyword(s):  
General Circulation ◽  
Phase Speed ◽  
Circulation Model ◽  
Meridional Wind ◽  
Equatorial Region ◽  
Middle Latitudes ◽  
Zonal Wavenumber ◽  
Westerly Winds ◽  
Summer Hemisphere ◽  
Stationary Planetary Wave

Abstract. The influence of the sudden stratosphere warming (SSW) on quasi-2 day wave (QTDW) with westward zonal wavenumber 3 (W3) is investigated using the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM). The summer easterly jet below 90 km is strengthened during an SSW, which results in a larger refractive index and thus more favorable condition for the propagation of W3. In the winter hemisphere, the Eliassen Palm (EP) flux diagnostics indicate that the strong instabilities at middle and high latitudes in the mesopause region are important for the amplification of W3, which are weakened during SSW periods due to the deceleration or even reversal of the winter westerly winds. Nonlinear interactions between the W3 and the wavenumber 1 stationary planetary wave produce QTDW with westward zonal wavenumber 2 (W2). The meridional wind perturbations of the W2 peak in the equatorial region, while the zonal wind and temperature components maximize at middle latitudes. The EP flux diagnostics indicate that the W2 is capable of propagating upward in both winter and summer hemispheres, whereas the propagation of W3 is mostly confined to the summer hemisphere. This characteristic is likely due to the fact that the phase speed of W2 is larger, and therefore its waveguide has a broader latitudinal extension. The larger phase speed also makes W2 less vulnerable to dissipation and critical layer filtering by the background wind when propagating upward.

The Response of Elastic and Viscoelastic Surfaces to a Turbulent Boundary Layer

1986 ◽  
Vol 53 (1) ◽  
pp. 206-212 ◽  
Author(s):  
Mohamed Gad-el-Hak
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Surface Deformation ◽  
Phase Speed ◽  
Instability Waves ◽  
Compliant Surface ◽  
Wave Characteristics ◽  
Highly Nonlinear ◽  
Nonlinear Static ◽  
High Phase

The unstable response of elastic and viscoelastic surfaces to a turbulent boundary layer was experimentally investigated in an 18-m towing tank. The compliant surface deformation was measured using a remote optical technique. The “Laser Displacement Gauge” employs a Reticon camera equipped with a linear array of 256 photodiodes spaced 25 microns apart. The device was used to measure the characteristics of two classes of hydroelastic instability waves that form on elastic or viscoelastic surfaces as a reuslt of the interaction with a turbulent boundary layer. The instability waves developing on an elastic surface are symmetric and have a relatively high phase speed and a small wavelength, as compared to the slow and highly nonlinear “static-divergence” waves observed on the viscoelastic surface. The experimentally determined wave characteristics are compared to existing theories on compliant surface instabilities.

scholarly journals Eastward-propagating planetary wave in the polar middle atmosphere

2021 ◽  
Author(s):  
Liang Tang ◽  
Sheng-Yang Gu ◽  
Xian-Kang Dou
Keyword(s):  
Zonal Wind ◽  
Planetary Wave ◽  
Middle Atmosphere ◽  
Flow Instability ◽  
Diagnostic Analysis ◽  
Background Wind ◽  
Mean Flow ◽  
Zonal Wavenumber ◽  
Critical Layers ◽  
The Mean

Abstract. We presented the global variations of the eastward propagating wavenumber 1 (E1), 2 (E2), 3 (E3), and 4 (E4) planetary waves (PWs) and their diagnostic results in the polar middle atmosphere, using MERRA-2 temperature and wind datasets in 2019. It is clearly shown that the eastward wave modes exist during winter periods with westward background wind in both hemispheres. The maximum wave amplitudes in the southern hemisphere (SH) are slightly larger and lie lower than those in the northern hemisphere (NH). It is also found that the wave perturbations peak at lower latitudes with smaller amplitude as the wavenumber increases. The period of the E1 mode varies from 3 to 5 days in both hemispheres, while the period of E2 mode is slightly longer in the NH (48 h) than in the SH (40 h). The periods of the E3 are ~30 h in both SH and NH, and the period of E4 is ~24 h. Though the wave periods become shorter as the wavenumber increases, their mean phase speeds are relatively stable, which are ~53, ~58, ~55, and ~52 m/s at 70° latitudes for W1, W2, W3, and W4, respectively. The eastward PWs occur earlier with increasing zonal wavenumber, which agrees well with the seasonal variations of the background zonal wind through the generation of critical layers. Diagnostic analysis also shows that the mean flow instability in the upper stratosphere and upper mesosphere may both contribute to the amplification of the eastward PWs.

Can we improve gravity wave parameterizations by imposing sources at all altitudes in the atmosphere?

2020 ◽  
Author(s):  
Bruno Ribstein ◽  
Christophe Millet ◽  
Francois Lott ◽  
Alvaro de la Camara
Keyword(s):  
Gravity Wave ◽  
General Circulation Model ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Phase Speed ◽  
Circulation Model ◽  
Reanalysis Data ◽  
Inertial Waves ◽  
Vertical Propagation

<p>A multiwave non-orographic gravity wave (GW) scheme is adapted to represent waves of small intrinsic phase speed and sources located at all altitudes in the troposphere and middle atmosphere. Using reanalysis data, these changes impose larger amplitude saturated waves everywhere in the middle atmosphere, which permits to produce more realistic GW vertical spectra than when the phase speeds are large and the sources are in the troposphere only. The same scheme, tested online in the Laboratoire de Météorologie Dynamique Zoom(LMDz) general circulation model, performs at least as well as the operational non-orographic GW scheme.  Some modest benefits are seen, for instance, in the equatorial tilt with altitude of the winter jets in the middle atmosphere. Although the scheme includes the effects of inertial waves, which are more and more often detected in the mesosphere, the configuration that gives a reasonable climatology in LMDz hinders the vertical propagation of these parameterized waves and do not generally reach mesospheric altitudes.</p>

Calculating the Natural Atmospheric Radiation Using the General Circulation Model of the Earth’s Lower and Middle Atmosphere

2020 ◽  
Vol 12 (5) ◽  
pp. 803-815
Author(s):  
B. N. Chetverushkin ◽  
I. V. Mingalev ◽  
E. A. Fedotova ◽  
K. G. Orlov ◽  
V. M. Chechetkin ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Atmospheric Radiation
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