Variability of Gravity Wave Effects on the Zonal Mean Circulation and Migrating Terdiurnal Tide as Studied With the Middle and Upper Atmosphere Model (MUAM2019) Using a Nonlinear Gravity Wave Scheme

Implementing a nonlinear gravity wave (GW) parameterization into a mechanistic middle and upper atmosphere model, which extends to the lower thermosphere (160 km), we study the response of the atmosphere in terms of the circulation patterns, temperature distribution, and migrating terdiurnal solar tide activity to the upward propagating small-scale internal GWs originating in the lower atmosphere. We perform three test simulations for the Northern Hemisphere winter conditions in order to assess the effects of variations in the initial GW spectrum on the climatology and tidal patterns of the mesosphere and lower thermosphere. We find that the overall strength of the source level momentum flux has a relatively small impact on the zonal mean climatology. The tails of the GW source level spectrum, however, are crucial for the lower thermosphere climatology. With respect to the terdiurnal tide, we find a strong dependence of tidal amplitude on the induced GW drag, generally being larger when GW drag is increased.

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Interaction of Small-Scale Gravity Waves with the Terdiurnal Solar Tide in the Mesosphere and Lower Thermosphere

10.5194/gmd-2019-339 ◽

2020 ◽

Author(s):

Friederike Lilienthal ◽

Erdal Yiğit ◽

Nadja Samtleben ◽

Christoph Jacobi

Keyword(s):

Strong Dependence ◽

Lower Thermosphere ◽

Lower Atmosphere ◽

Small Scale ◽

Tidal Amplitude ◽

Circulation Patterns ◽

Solar Tide ◽

Source Level ◽

Mesosphere And Lower Thermosphere ◽

Hemisphere Winter

Abstract. Implementing a nonlinear whole atmosphere gravity wave (GW) parameterization into the Middle and Upper Atmosphere Model extending to the lower thermosphere (160 km), we study the response of the atmosphere in terms of the circulation patterns, temperature distribution, and migrating terdiurnal solar tide activity to the upward propagating small-scale internal GWs originating in the lower atmosphere. We perform three test simulations for the Northern Hemisphere winter conditions in order to assess the effects of variations in the initial GW spectrum on the dynamics of the mesosphere and lower thermosphere. We find that the overall strength of the source level momentum flux has a comparatively small impact on zonal mean dynamics. The tails of the GW source level spectrum, however, are crucial for the lower thermosphere dynamics. With respect to the terdiurnal tide, we find a strong dependence of tidal amplitude on the induced GW drag, generally being larger when GW drag is increased.

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Kelvin-Helmholtz billows and their effects on mean state during gravity wave propagation

Annales Geophysicae ◽

10.5194/angeo-27-2789-2009 ◽

2009 ◽

Vol 27 (7) ◽

pp. 2789-2798 ◽

Cited By ~ 12

Author(s):

X. Liu ◽

J. Xu ◽

H. Gao ◽

G. Chen

Keyword(s):

Gravity Wave ◽

Lower Thermosphere ◽

Dominant Mode ◽

Lower Atmosphere ◽

Wave Number ◽

Small Scale ◽

Mean Flow ◽

Triggering Mechanism ◽

The Mean ◽

Mlt Region

Abstract. The Kelvin-Helmholtz (KH) billows which appear in the process of gravity wave (GW) propagation are simulated directly by using a compressible nonlinear two-dimensional gravity wave model. The differences between our model and others include: the background field has no special initial configuration and there is no initial triggering mechanism needed in the mesosphere and lower thermosphere (MLT) region to excite the KH billows. However, the initial triggering mechanism is performed in the lower atmosphere through GW, which then propagate into the MLT region and form billows. The braid structures and overturning of KH billows, caused by nonlinear interactions between GWs and mean flow, can be resolved precisely by the model. These results support the findings in airglow studies that GWs propagating from below into the MLT region are important sources of KH billows. The onset of small scale waves and the wave energy transfer induce the shallower vertical wave number power spectral densities (PSD). However, most of the slopes are steeper than the expected kz−3 power law, which indicates that GWs with 10 km vertical wavelength are still a dominant mode. The results also show that the evolution of mean wind vary substantially between the different processes of GWs propagation. Before the KH billows evolve, the mean wind is accelerated greatly by GWs. By contrast, as the KH billows evolve and mix with mean flow, the mean wind and its peak value decrease.

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Enhanced gravity-wave activity and interhemispheric coupling during the MaCWAVE/MIDAS northern summer program 2002

Annales Geophysicae ◽

10.5194/angeo-24-1175-2006 ◽

2006 ◽

Vol 24 (4) ◽

pp. 1175-1188 ◽

Cited By ~ 63

Author(s):

E. Becker ◽

D. C. Fritts

Keyword(s):

Gravity Wave ◽

Rossby Wave ◽

Lower Thermosphere ◽

Wave Activity ◽

Lower Atmosphere ◽

Summer Program ◽

Latent Heating ◽

Austral Winter ◽

Northern Summer ◽

Mesosphere And Lower Thermosphere

Abstract. We present new sensitivity experiments that link observed anomalies of the mesosphere and lower thermosphere at high latitudes during the MaCWAVE/MIDAS summer program 2002 to enhanced planetary Rossby-wave activity in the austral winter troposphere. We employ the same general concept of a GCM having simplified representations of radiative and latent heating as in a previous study by Becker et al. (2004). In the present version, however, the model includes no gravity wave (GW) parameterization. Instead we employ a high vertical and a moderate horizontal resolution in order to describe GW effects explicitly. This is supported by advanced, nonlinear momentum diffusion schemes that allow for a self-consistent generation of inertia and mid-frequency GWs in the lower atmosphere, their vertical propagation into the mesosphere and lower thermosphere, and their subsequent dissipation which is induced by prescribed horizontal and vertical mixing lengths as functions of height. The main anomalies in northern summer 2002 consist of higher temperatures than usual above 82 km, an anomalous eastward mean zonal wind between 70 and 90 km, an altered meridional flow, enhanced turbulent dissipation below 80 km, and enhanced temperature variations associated with GWs. These signals are all reasonably described by differences between two long-integration perpetual model runs, one with normal July conditions, and another run with modified latent heating in the tropics and Southern Hemisphere to mimic conditions that correspond to the unusual austral winter 2002. The model response to the enhanced winter hemisphere Rossby-wave activity has resulted in both an interhemispheric coupling through a downward shift of the GW-driven branch of the residual circulation and an increased GW activity at high summer latitudes. Thus a quantitative explanation of the dynamical state of the northern mesosphere and lower thermosphere during June-August 2002 requires an enhanced Lorenz energy cycle and correspondingly enhanced GW sources in the troposphere, which in the model show up in both hemispheres.

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Ionosphere Influenced From Lower-Lying Atmospheric Regions

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.651445 ◽

2021 ◽

Vol 8 ◽

Author(s):

Petra Koucká Knížová ◽

Jan Laštovička ◽

Daniel Kouba ◽

Zbyšek Mošna ◽

Katerina Podolská ◽

...

Keyword(s):

Current Knowledge ◽

Source Region ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Small Scale ◽

Atmospheric Waves ◽

Ionospheric Variability ◽

Secular Variations ◽

Wide Scale ◽

Academy Of Sciences

The ionosphere represents part of the upper atmosphere. Its variability is observed on a wide-scale temporal range from minutes, or even shorter, up to scales of the solar cycle and secular variations of solar energy input. Ionosphere behavior is predominantly determined by solar and geomagnetic forcing. However, the lower-lying atmospheric regions can contribute significantly to the resulting energy budget. The energy transfer between distant atmospheric parts happens due to atmospheric waves that propagate from their source region up to ionospheric heights. Experimental observations show the importance of the involvement of the lower atmosphere in ionospheric variability studies in order to accurately capture small-scale features of the upper atmosphere. In the Part I Coupling, we provide a brief overview of the influence of the lower atmosphere on the ionosphere and summarize the current knowledge. In the Part II Coupling Evidences Within Ionospheric Plasma—Experiments in Midlatitudes, we demonstrate experimental evidence from mid-latitudes, particularly those based on observations by instruments operated by the Institute of Atmospheric Physics, Czech Academy of Sciences. The focus will mainly be on coupling by atmospheric waves.

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SMLTM simulations of the diurnal tide: comparison with UARS observations

Annales Geophysicae ◽

10.1007/s00585-997-1187-7 ◽

1997 ◽

Vol 15 (9) ◽

pp. 1187-1197 ◽

Cited By ~ 20

Author(s):

R. A. Akmaev ◽

V. A. Yudin ◽

D. A. Ortland

Keyword(s):

Gravity Wave ◽

Seasonal Variations ◽

Lower Thermosphere ◽

Lower Boundary ◽

Eddy Diffusion ◽

Lower Atmosphere ◽

Diurnal Tide ◽

Tidal Waves ◽

Dominant Component ◽

Dynamics Simulations

Abstract. Wind and temperature observations in the mesosphere and lower thermosphere (MLT) from the Upper Atmosphere Research Satellite (UARS) reveal strong seasonal variations of tides, a dominant component of the MLT dynamics. Simulations with the Spectral mesosphere/lower thermosphere model (SMLTM) for equinox and solstice conditions are presented and compared with the observations. The diurnal tide is generated by forcing specified at the model lower boundary and by in situ absorption of solar radiation. The model incorporates realistic parameterizations of physical processes including various dissipation processes important for propagation of tidal waves in the MLT. A discrete multi-component gravity-wave parameterization has been modified to account for seasonal variations of the background temperature. Eddy diffusion is calculated depending on the gravity-wave energy deposition rate and stability of the background flow. It is shown that seasonal variations of the diurnal-tide amplitudes are consistent with observed variations of gravity-wave sources in the lower atmosphere.

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Review of "Impact of Gravity wave drag on the thermospheric circulation: Implementation of a nonlinear gravity wave parameterization in a whole atmosphere model"

10.5194/angeo-2019-36-rc2 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

Gravity Wave ◽

Wave Drag ◽

Atmosphere Model ◽

Nonlinear Gravity

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Effects of Latitude-Dependent Gravity Wave Source Variations on the Middle and Upper Atmosphere

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2020.614018 ◽

2021 ◽

Vol 7 ◽

Author(s):

Erdal Yiğit ◽

Alexander S. Medvedev ◽

Manfred Ern

Keyword(s):

General Circulation ◽

Middle Atmosphere ◽

Lower Thermosphere ◽

Three Dimensional ◽

Circulation Model ◽

Wave Activity ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Boreal Summer ◽

Wave Source

Atmospheric gravity waves (GWs) are generated in the lower atmosphere by various weather phenomena. They propagate upward, carry energy and momentum to higher altitudes, and appreciably influence the general circulation upon depositing them in the middle and upper atmosphere. We use a three-dimensional first-principle general circulation model (GCM) with implemented nonlinear whole atmosphere GW parameterization to study the global climatology of wave activity and produced effects at altitudes up to the upper thermosphere. The numerical experiments were guided by the GW momentum fluxes and temperature variances as measured in 2010 by the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument onboard NASA’s TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) satellite. This includes the latitudinal dependence and magnitude of GW activity in the lower stratosphere for the boreal summer season. The modeling results were compared to the SABER temperature and total absolute momentum flux and Upper Atmosphere Research Satellite (UARS) data in the mesosphere and lower thermosphere. Simulations suggest that, in order to reproduce the observed circulation and wave activity in the middle atmosphere, GW fluxes that are smaller than observed fluxes have to be used at the source level in the lower atmosphere. This is because observations contain a broader spectrum of GWs, while parameterizations capture only a portion relevant to the middle and upper atmosphere dynamics. Accounting for the latitudinal variations of the source appreciably improves simulations.

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Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-7617-2020 ◽

2020 ◽

Vol 20 (12) ◽

pp. 7617-7644

Author(s):

In-Sun Song ◽

Changsup Lee ◽

Hye-Yeong Chun ◽

Jeong-Han Kim ◽

Geonhwa Jee ◽

...

Keyword(s):

Ray Tracing ◽

Gravity Waves ◽

Lower Thermosphere ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Wave Number ◽

Horizontal Wind ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Curvature Effects

Abstract. Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D; x–z and t) and two-dimensional (2D; z and t) results are compared for various parameterized pseudomomentum fluxes. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers due to refraction and curvature effects can make it more possible that GWs elude critical level filtering and saturation in the lower atmosphere. GW focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wave number 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.

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Non-zonal structures of the midlatitude mesosphere/lower thermosphere dynamics studied by using atmospheric models and radar observations.

10.5194/dach2022-164 ◽

2021 ◽

Author(s):

Kanykei Kandieva ◽

Christoph Jacobi ◽

Khalil Karami ◽

Alexander Pogoreltsev ◽

Evgeny Merzlyakov ◽

...

Keyword(s):

Zonal Wind ◽

Lower Thermosphere ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Radar Observations ◽

Wind Variability ◽

Hydrostatic Model ◽

Dynamical Features ◽

Wind Distribution ◽

Longitudinal Variability

Radar observations from two SKiYMET radars at Collm (51&#176;N, 13&#176;E) and Kazan (56&#176;N, 49&#176;E) during 2016-2017 are used to investigate the longitudinal variability of the mesosphere/lower thermosphere (MLT) wind regime over western and eastern Europe. Both of the meteor radars have similar setups and apply the same analysis procedures to correctly compare MLT parameters and validate the simulated winds. The radar observations confirm the established seasonal variability of the wind distribution, but this distribution is not identical for the two stations. The results show good qualitative agreement with global circulations model predictions by the Middle and Upper Atmosphere Model (MUAM) and the Upper Atmosphere ICOsahedral Non-hydrostatic model (UA-ICON). The MUAM and UA-ICON models well reproduce the main dynamical features, namely the vertical and temporal distributions of the winds observed throughout the year. However, there are also some differences in the longitudinal wind variability of the models and radar observations. Numerical experiments with modified parameterization settings have also been carried out to study the response of the MLT wind circulation to the gravity waves originating from the lower atmosphere. The MUAM model results show that a decrease/increase in the gravity wave intensity at the lower atmosphere leads to an increase/decrease of the mesospheric zonal wind jet extension and the zonal wind reversal.

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Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

10.5194/egusphere-egu21-1909 ◽

2021 ◽

Author(s):

In-Sun Song ◽

Changsup Lee ◽

Hye-Yeong Chun ◽

Jeong-Han Kim ◽

Geonhwa Jee ◽

...

Keyword(s):

Ray Tracing ◽

Gravity Waves ◽

Lower Thermosphere ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Horizontal Wind ◽

Stratospheric Warming ◽

Sudden Stratospheric Warming ◽

Curvature Effects ◽

Zonal Wavenumber

Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D;&#160;x&#8211;z&#160;and&#160;t) and two-dimensional (2D;&#160;z&#160;and&#160;t) results are compared for various parameterized pseudomomentum fluxes. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers due to refraction and curvature effects can make it more possible that GWs elude critical level filtering and saturation in the lower atmosphere. GW focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wavenumber 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.

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