Constraints on a Non-orographic Gravity Wave Drag Parameterization Using a Gravity Wave Resolving General Circulation Model

The Antarctic stratospheric final warming (SFW) is usually simulated with a substantial delay in climate models, and the corresponding temperatures in austral spring are lower than observations, implying insufficient stratospheric wave drag. To investigate the role of orographic gravity wave drag (GWD) in modeling the Antarctic SFW, in this study the orographic GWD parameterization scheme is modified in the middle-atmosphere version of the Beijing Climate Center Atmospheric General Circulation Model. A pair of simulations are conducted to compare two orographic GWD schemes in simulating the breakdown of the stratospheric polar vortex over Antarctica. The control simulation with the default orographic GWD scheme exhibits delayed vortex breakdown and the cold-pole bias seen in most climate models. In the simulation with modified orographic GWD scheme, the simulated vortex breaks down earlier by 8 days, and the associated cold-pole bias is reduced by more than 2 K. The modified scheme provides stronger orographic GWD in the lower stratosphere, which drives an accelerated polar downwelling branch of the Brewer–Dobson circulation and, in turn, produces adiabatic warming. Our study suggests that modifying orographic GWD parameterizations in climate models would be a valid way of improving the SFW simulation over Antarctica.

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Simulating the QBO in an Atmospheric General Circulation Model: Sensitivity to Resolved and Parameterized Forcing

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-15-0099.1 ◽

2016 ◽

Vol 73 (4) ◽

pp. 1649-1665 ◽

Cited By ~ 24

Author(s):

James A. Anstey ◽

John F. Scinocca ◽

Martin Keller

Keyword(s):

Gravity Wave ◽

General Circulation Model ◽

General Circulation ◽

Atmospheric General Circulation Model ◽

Circulation Model ◽

Wave Drag ◽

Vertical Resolution ◽

Atmospheric General Circulation ◽

Downward Influence ◽

Seasonal Synchronization

Abstract The quasi-biennial oscillation (QBO) of tropical stratospheric zonal winds is simulated in an atmospheric general circulation model and its sensitivity to model parameters is explored. Vertical resolution in the lower tropical stratosphere finer than ≈1 km and sufficiently strong forcing by parameterized nonorographic gravity wave drag are both required for the model to exhibit a QBO-like oscillation. Coarser vertical resolution yields oscillations that are seasonally synchronized and driven mainly by gravity wave drag. As vertical resolution increases, wave forcing in the tropical lower stratosphere increases and seasonal synchronization is disrupted, allowing quasi-biennial periodicity to emerge. Seasonal synchronization could result from the form of wave dissipation assumed in the gravity wave parameterization, which allows downward influence by semiannual oscillation (SAO) winds, whereas dissipation of resolved waves is consistent with radiative damping and no downward influence. Parameterized wave drag is nevertheless required to generate a realistic QBO, effectively acting to amplify the relatively weaker mean-flow forcing by resolved waves.

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Test of a convectively forced gravity wave drag parameterization in a general circulation model

Asia-Pacific Journal of Atmospheric Sciences ◽

10.1007/s13143-010-0001-8 ◽

2010 ◽

Vol 46 (1) ◽

pp. 1-10 ◽

Cited By ~ 10

Author(s):

Jong-Hun Jeon ◽

Song-You Hong ◽

Hye-Yeong Chun ◽

In-Sun Song

Keyword(s):

Gravity Wave ◽

General Circulation Model ◽

General Circulation ◽

Circulation Model ◽

Wave Drag

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A Simple Technique to Infer the Missing Gravity Wave Drag in the Middle Atmosphere Using a General Circulation Model: Potential Vorticity Budget

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-13-0198.1 ◽

2014 ◽

Vol 71 (2) ◽

pp. 683-696 ◽

Cited By ~ 8

Author(s):

Manuel Pulido

Keyword(s):

Gravity Wave ◽

General Circulation Model ◽

Potential Vorticity ◽

General Circulation ◽

Simple Technique ◽

Circulation Model ◽

Wave Drag ◽

External Momentum ◽

Sources And Sinks ◽

Missing Momentum

Abstract A simple technique to infer the missing momentum forcing in a general circulation model is developed and evaluated. The response of the large-scale dynamic equations to an external momentum forcing presents a nonlocal response in the zonal and meridional wind. On the other hand, the response to the external momentum forcing in the potential vorticity (PV) is a local growing geostrophic mode, so that there is a direct relationship between the external momentum forcing and the response in PV. In this work, this fact is exploited to diagnose the missing momentum forcing in the extratropics using a general circulation model. The capability of the simple technique to estimate a concentrated gravity wave forcing is evaluated. A dynamical model is evolved with prescribed sources and sinks of PV and then the technique is used to estimate these known momentum sources and sinks. PV is found to give a much better diagnostic of gravity wave drag compared to the more traditional zonal wind differences. The technique is also used in a realistic environment, in which the sources and sinks of PV in Met Office analyses are determined. The estimation of this missing forcing with this simple technique is compared with the estimation given by a more complex data assimilation technique developed by Pulido and Thuburn and, in general, a good agreement is found. The simple gravity wave drag estimation technique can be used in an online data assimilation cycle, using the increments of the analysis, and also offline, using a general circulation model and observations.

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The GCM Response to Current Parameterizations of Nonorographic Gravity Wave Drag

Journal of the Atmospheric Sciences ◽

10.1175/jas3483.1 ◽

2005 ◽

Vol 62 (7) ◽

pp. 2394-2413 ◽

Cited By ~ 61

Author(s):

Charles McLandress ◽

John F. Scinocca

Keyword(s):

Gravity Wave ◽

General Circulation ◽

Critical Level ◽

Climate Modeling ◽

Circulation Model ◽

Wave Drag ◽

Nonlinear Dissipation ◽

Additional Experiment ◽

Identical Response ◽

Dissipation Mechanism

Abstract A comparison is undertaken of the response of a general circulation model (GCM) to the nonorographic gravity wave drag parameterizations of Hines, Warner and McIntyre, and Alexander and Dunkerton. The analysis is restricted to a comparison of each parameterization’s nonlinear dissipation mechanism since, in principle, this is the only component that differs between the schemes. This is achieved by developing a new, more general parameterization that can represent each of these dissipation mechanisms, while keeping all other aspects of the problem identical. The GCM simulations reveal differences in the climatological response to the three dissipation mechanisms. These differences are documented for both tropopause and surface launch elevations of the parameterized waves. The simulations also reveal systematic differences in the height at which momentum is deposited. This behavior is investigated further in a set of experiments designed to reduce these systematic differences, while leaving the details of the dissipation mechanisms unaltered. These sensitivity experiments demonstrate that it is possible to obtain nearly identical responses from all three mechanisms, which indicates that the GCM response is largely insensitive to the precise details of the dissipation mechanisms. This finding is supported by an additional experiment in which the nonlinear dissipation mechanisms are turned off and critical-level filtering is left to act as the only source of dissipation. In this experiment, critical-level filtering effectively replaces the nonlinear dissipation mechanism, producing a nearly identical response. The results of this study suggest that climate modeling efforts would potentially benefit more from the refinement of other aspects of the parameterization problem, such as the properties of the launch spectrum, than they have benefited from the refinement of dissipation mechanisms.

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Annual Cycle of Gravity Wave Activity Derived From a High‐Resolution Martian General Circulation Model

Journal of Geophysical Research Planets ◽

10.1029/2018je005847 ◽

2019 ◽

Cited By ~ 4

Author(s):

Takeshi Kuroda ◽

Erdal Yiğit ◽

Alexander S. Medvedev

Keyword(s):

High Resolution ◽

Gravity Wave ◽

General Circulation Model ◽

Annual Cycle ◽

General Circulation ◽

Circulation Model ◽

Wave Activity

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Influence of gravity wave drag parametrisations on the stratospheric circulation of seasonal ICON-NWP experiments

10.5194/egusphere-egu2020-17139 ◽

2020 ◽

Author(s):

Raphael Köhler ◽

Dörthe Handorf ◽

Ralf Jaiser ◽

Klaus Dethloff ◽

Günther Zängl ◽

...

Keyword(s):

Gravity Wave ◽

General Circulation ◽

Weather Prediction ◽

Polar Vortex ◽

Circulation Model ◽

Seasonal Prediction ◽

Wave Drag ◽

Stratospheric Polar Vortex ◽

Sensitivity Experiments ◽

Hemisphere Winter

<p>The stratospheric polar vortex is highly variable in winter and thus, models often struggle to capture its variability and strength. Yet, the influence of the stratosphere on the tropospheric circulation becomes highly important in Northern Hemisphere winter and is one of the main potential sources for subseasonal to seasonal prediction skill in mid latitudes. Mid-latitude extreme weather patterns in winter are often preceded by sudden stratospheric warmings (SSWs), which are the strongest manifestation of the coupling between stratosphere and troposphere. Misrepresentation of the SSW-frequency and stratospheric biases in models can therefore also cause biases in the troposphere.</p><p>In this context this work comprises the analysis of four seasonal ensemble experiments with a high-resolution, nonhydrostatic global atmospheric general circulation model in numerical weather prediction mode (ICON-NWP). The main focus thereby lies on the variability and strength of the stratospheric polar vortex. We identified the gravity wave drag parametrisations as one important factor influencing stratospheric dynamics. As the control experiment with default gravity wave drag settings exhibits an overestimated amount of SSWs and a weak stratospheric polar vortex, three sensitivity experiments with adjusted drag parametrisations were generated. Hence, the parametrisations for the non-orographic gravity wave drag and the subgrid&#8208;scale orographic (SSO) drag were chosen with the goal of strengthening the stratospheric polar vortex. Biases to ERA-Interim are reduced with both adjustments, especially in high latitudes. Whereas the positive effect of the reduced non-orographic gravity wave drag is strongest in the mid-stratosphere in winter, the adjusted SSO-scheme primarily affects the troposphere by reducing mean sea level pressure biases in all months. A fourth experiment using both adjustments exhibits improvements in the troposphere and stratosphere. Although the stratospheric polar vortex in winter is strengthened in all sensitivity experiments, it is still simulated too weak compared to ERA-Interim. Further mechanisms causing this weakness are also investigated in this study.</p>

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Development of the GEOS-5 atmospheric general circulation model: evolution from MERRA to MERRA2

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-7575-2014 ◽

2014 ◽

Vol 7 (6) ◽

pp. 7575-7617 ◽

Cited By ~ 1

Author(s):

A. Molod ◽

L. Takacs ◽

M. Suarez ◽

J. Bacmeister

Keyword(s):

General Circulation Model ◽

General Circulation ◽

Atmospheric General Circulation Model ◽

Weather Prediction ◽

Circulation Model ◽

Wave Drag ◽

Atmospheric General Circulation ◽

Wide Range ◽

Simulated Climate ◽

The Impact

Abstract. The Modern-Era Retrospective Analysis for Research and Applications-2 (MERRA2) version of the GEOS-5 Atmospheric General Circulation Model (AGCM) is currently in use in the NASA Global Modeling and Assimilation Office (GMAO) at a wide range of resolutions for a variety of applications. Details of the changes in parameterizations subsequent to the version in the original MERRA reanalysis are presented here. Results of a series of atmosphere-only sensitivity studies are shown to demonstrate changes in simulated climate associated with specific changes in physical parameterizations, and the impact of the newly implemented resolution-aware behavior on simulations at different resolutions is demonstrated. The GEOS-5 AGCM presented here is the model used as part of the GMAO's MERRA2 reanalysis, the global mesoscale "nature run", the real-time numerical weather prediction system, and for atmosphere-only, coupled ocean–atmosphere and coupled atmosphere–chemistry simulations. The seasonal mean climate of the MERRA2 version of the GEOS-5 AGCM represents a substantial improvement over the simulated climate of the MERRA version at all resolutions and for all applications. Fundamental improvements in simulated climate are associated with the increased re-evaporation of frozen precipitation and cloud condensate, resulting in a wetter atmosphere. Improvements in simulated climate are also shown to be attributable to changes in the background gravity wave drag, and to upgrades in the relationship between the ocean surface stress and the ocean roughness. The series of "resolution aware" parameters related to the moist physics were shown to result in improvements at higher resolutions, and result in AGCM simulations that exhibit seamless behavior across different resolutions and applications.

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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 ◽

2019 ◽

Author(s):

Yasunobu Miyoshi ◽

Erdal Yiğit

Keyword(s):

Gravity Wave ◽

General Circulation ◽

Lower Thermosphere ◽

Circulation Model ◽

Wave Drag ◽

Zonal Wavenumber ◽

Semidiurnal Variation ◽

Solar Tide ◽

Atmosphere General Circulation Model ◽

Thermospheric Dynamics

Abstract. To investigate the effects of the gravity wave (GW) drag on the general circulation in the thermosphere, a nonlinear GW parameterization that estimates the GW drag in the whole atmosphere system is implemented in a whole atmosphere general circulation model (GCM). Comparing the simulation results obtained with the whole atmosphere scheme with the ones obtained with a conventional linear scheme, we study the GW effects on the thermospheric dynamics for solstice conditions. The GW drag significantly decelerates the mean zonal wind in the thermosphere. The GWs attenuate the migrating semidiurnal solar tide (SW2) amplitude in the lower thermosphere, and modifies the latitudinal structure of the SW2 above 150 km height. The SW2 simulated by the GCM based on the nonlinear whole atmosphere scheme agrees well with the observed SW2. The GW drag in the lower thermosphere has zonal wavenumber 2 and semidiurnal variation, while the GW drag above 150 km height is enhanced in high latitude. The GW drag in the thermosphere is a significant dynamical and plays an important role in the momentum budget of the thermosphere. Therefore, a GW parameterization accounting for thermospheric processes is essential for coarse-grid whole atmosphere GCMs in order to more realistically simulate the atmosphere-ionosphere system.

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