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

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.

Formation of the double stratopause and elevated stratopause associated with the major stratospheric sudden warming in 2018/19

2021 ◽  
Author(s):  
Haruka Okui ◽  
Kaoru Sato ◽  
Dai Koshin ◽  
Shingo Watanabe
Keyword(s):  
General Circulation ◽  
Middle Atmosphere ◽  
Baroclinic Instability ◽  
Lower Thermosphere ◽  
Circulation Model ◽  
Lower Atmosphere ◽  
Temperature Structure ◽  
Residual Circulation ◽  
Stratospheric Sudden Warming

<p>After several recent stratospheric sudden warming (SSW) events, the stratopause disappeared and reformed at a higher altitude, forming an elevated stratopause (ES). The relative roles of atmospheric waves in the mechanism of ES formation are still not fully understood. We performed a hindcast of the 2018/19 SSW event using a gravity-wave (GW) permitting general circulation model containing the mesosphere and lower thermosphere (MLT), and analyzed dynamical phenomena throughout the entire middle atmosphere. An ES formed after the major warming on 1 January 2019. There was a marked temperature maximum in the polar upper mesosphere around 28 December 2018 prior to the disappearance of the descending stratopause associated with the SSW. This temperature structure with two maxima in the vertical is referred to as a double stratopause (DS). We showed that adiabatic heating from the residual circulation driven by GW forcing (GWF) causes barotropic and/or baroclinic instability before DS formation, causing in situ generation of planetary waves (PWs). These PWs propagate into the MLT and exert negative forcing, which contributes to DS formation. Both negative GWF and PWF above the recovered eastward jet play crucial roles in ES formation. The altitude of the recovered eastward jet, which regulates GWF and PWF height, is likely affected by the DS structure. Simple vertical propagation from the lower atmosphere is insufficient to explain the presence of the GWs observed in this event.</p>

scholarly journals Influence of gravity waves on the climatology of high-altitude Martian carbon dioxide ice clouds

2018 ◽  
Author(s):  
Erdal Yiğit ◽  
Alexander S. Medvedev ◽  
Paul Hartogh
Keyword(s):  
Carbon Dioxide ◽  
High Altitude ◽  
Gravity Waves ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Upper Atmosphere ◽  
Cloud Formation ◽  
Ice Clouds ◽  
Ice Cloud

Abstract. Carbon dioxide (CO2) ice clouds have been routinely observed in the middle atmosphere of Mars. However, there are still uncertainties concerning physical mechanisms that control their altitude, geographical, and seasonal distributions. Using the Max Planck Institute Martian General Circulation Model (MPI-MGCM), incorporating a state-of-the-art whole atmosphere subgrid-scale gravity wave parameterization (Yiğit et al., 2008), we demonstrate that internal gravity waves generated by lower atmospheric weather processes have wide reaching impact on the Martian climate. Globally, GWs cool the upper atmosphere of Mars by ~10 % and facilitate high-altitude CO2 ice cloud formation. CO2 ice cloud seasonal variations in the mesosphere and the mesopause region appreciably coincide with the spatio-temporal variations of GW effects, providing insight into the observed distribution of clouds. Our results suggest that GW propagation and dissipation constitute a necessary physical mechanism for CO2 ice cloud formation in the Martian upper atmosphere during all seasons.

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 A study into the effect of the diurnal tide on the structure of the background mesosphere and thermosphere using the new coupled middle atmosphere and thermosphere (CMAT) general circulation model

2002 ◽  
Vol 20 (2) ◽  
pp. 225-235 ◽  
Author(s):  
M. J. Harris ◽  
N. F. Arnold ◽  
A. D. Aylward
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Atomic Oxygen ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Lower Boundary ◽  
Circulation Model ◽  
Diurnal Tide ◽  
Temperature Structure ◽  
The Mean

Abstract. A new coupled middle atmosphere and thermosphere general circulation model has been developed, and some first results are presented. An investigation into the effects of the diurnal tide upon the mean composition, dynamics and energetics was carried out for equinox conditions. Previous studies have shown that tides deplete mean atomic oxygen in the upper mesosphere-lower thermosphere due to an increased recombination in the tidal displaced air parcels. The model runs presented suggest that the mean residual circulation associated with the tidal dissipation also plays an important role. Stronger lower boundary tidal forcing was seen to increase the equatorial local diurnal maximum of atomic oxygen and the associated 0(1S) 557.7 nm green line volume emission rates. The changes in the mean background temperature structure were found to correspond to changes in the mean circulation and exothermic chemical heating.Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry) Meterology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

scholarly journals The upper-atmosphere extension of the ICON general circulation model (version: ua-icon-1.0)

2019 ◽  
Vol 12 (8) ◽  
pp. 3541-3569 ◽  
Author(s):  
Sebastian Borchert ◽  
Guidi Zhou ◽  
Michael Baldauf ◽  
Hauke Schmidt ◽  
Günther Zängl ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Mass Conservation ◽  
Research Area ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Triangular Grid ◽  
Max Planck ◽  
Dynamical Core

Abstract. How the upper-atmosphere branch of the circulation contributes to and interacts with the circulation of the middle and lower atmosphere is a research area with many open questions. Inertia–gravity waves, for instance, have moved in the focus of research as they are suspected to be key features in driving and shaping the circulation. Numerical atmospheric models are an important pillar for this research. We use the ICOsahedral Non-hydrostatic (ICON) general circulation model, which is a joint development of the Max Planck Institute for Meteorology (MPI-M) and the German Weather Service (DWD), and provides, e.g., local mass conservation, a flexible grid nesting option, and a non-hydrostatic dynamical core formulated on an icosahedral–triangular grid. We extended ICON to the upper atmosphere and present here the two main components of this new configuration named UA-ICON: an extension of the dynamical core from shallow- to deep-atmosphere dynamics and the implementation of an upper-atmosphere physics package. A series of idealized test cases and climatological simulations is performed in order to evaluate the upper-atmosphere extension of ICON.

scholarly journals The upper-atmosphere extension of the ICON general circulation model

2018 ◽  
Author(s):  
Sebastian Borchert ◽  
Guidi Zhou ◽  
Michael Baldauf ◽  
Hauke Schmidt ◽  
Günther Zängl ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Mass Conservation ◽  
Research Area ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Triangular Grid ◽  
Max Planck ◽  
Dynamical Core

Abstract. How the upper-atmosphere branch of the circulation contributes to and interacts with the circulation of the middle and lower atmosphere is a research area with many open questions. Inertia-gravity waves, for instance, have moved in the focus of research as they are suspected to be key features in driving and shaping the circulation. Numerical atmospheric models are an important pillar for this research. We use the ICOsahedral Non-hydrostatic (ICON) general circulation model, which is a joint development of the Max Planck Institute for Meteorology (MPI-M) and the German Weather Service (DWD), and provides, e.g., local mass conservation, a flexible grid nesting option and a non-hydrostatic dynamical core formulated on an icosahedral-triangular grid. We extended ICON to the upper atmosphere and present here the two main components of this new configuration named UA-ICON: an extension of the dynamical core from shallow- to deep-atmosphere dynamics, and the implementation of an upper-atmosphere physics package. A series of test cases and climatological simulations show that UA-ICON performs satisfactorily and is in good agreement with the observed global atmospheric circulation.

scholarly journals Influence of gravity waves on the climatology of high-altitude Martian carbon dioxide ice clouds

2018 ◽  
Vol 36 (6) ◽  
pp. 1631-1646 ◽  
Author(s):  
Erdal Yiğit ◽  
Alexander S. Medvedev ◽  
Paul Hartogh
Keyword(s):  
Carbon Dioxide ◽  
High Altitude ◽  
Gravity Waves ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Upper Atmosphere ◽  
Cloud Formation ◽  
Ice Clouds ◽  
Ice Cloud

Abstract. Carbon dioxide (CO2) ice clouds have been routinely observed in the middle atmosphere of Mars. However, there are still uncertainties concerning physical mechanisms that control their altitude, geographical, and seasonal distributions. Using the Max Planck Institute Martian General Circulation Model (MPI-MGCM), incorporating a state-of-the-art whole atmosphere subgrid-scale gravity wave parameterization (Yiğit et al., 2008), we demonstrate that internal gravity waves generated by lower atmospheric weather processes have a wide-reaching impact on the Martian climate. Globally, GWs cool the upper atmosphere of Mars by ∼10 % and facilitate high-altitude CO2 ice cloud formation. CO2 ice cloud seasonal variations in the mesosphere and the mesopause region appreciably coincide with the spatio-temporal variations of GW effects, providing insight into the observed distribution of clouds. Our results suggest that GW propagation and dissipation constitute a necessary physical mechanism for CO2 ice cloud formation in the Martian upper atmosphere during all seasons.

INM RAS coupled atmosphere–ionosphere general circulation model INMAIM (0–130 km)

2018 ◽  
Vol 33 (6) ◽  
pp. 351-357 ◽  
Author(s):  
Dmitry V. Kulyamin ◽  
Evgenii M. Volodin
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Plasma Chemistry ◽  
Lower Ionosphere ◽  
Circulation Model ◽  
Radiative Processes ◽  
Mesosphere And Lower Thermosphere ◽  
Climatic Characteristics

Abstract The paper presents a new INM RAS atmospheric general circulation model, which includes troposphere, stratosphere, mesosphere, and the lower thermosphere, as well as the lower ionospheric regions (INMAIM). Based on the atmospheric part of the INM climatic model INMCM, a new general circulation model was created by adding the middle atmosphere and lower ionosphere description up to 130 km altitudes. A new computational unit for radiative processes calculation was developed for this purpose. For the lower ionosphere a separate plasma chemistry local model was created. The identification of the INMAIM model climate in the mesosphere and lower thermosphere was carried out based on climatological observations. It was shown that model reproduces the general climatic characteristics considerably well.

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