Wave-Mean-Flow Interactions

1997 ◽  
pp. 47-57
Author(s):  
James R. Holton
Keyword(s):  
Mean Flow ◽  
Flow Interactions

scholarly journals Wave-mean flow interactions in the upper atmosphere

1973 ◽  
Vol 4 (1-4) ◽  
pp. 327-343 ◽  
Author(s):  
Richard S. Lindzen
Keyword(s):  
Upper Atmosphere ◽  
Mean Flow ◽  
Flow Interactions

Advancing the simulation of mesoscale eddies: Backscatter schemes in eddy-permitting ocean simulations

2021 ◽  
Author(s):  
Stephan Juricke ◽  
Sergey Danilov ◽  
Marcel Oliver ◽  
Nikolay Koldunov ◽  
Dmitry Sidorenko ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Large Scale ◽  
Mesoscale Eddy ◽  
Ocean Model ◽  
Mean Flow ◽  
Ocean Coupling ◽  
Climate Simulations ◽  
Flow Interactions ◽  
To Come ◽  
Eddy Dynamics

<p>Capturing mesoscale eddy dynamics is crucial for accurate simulations of the large-scale ocean currents as well as oceanic and climate variability. Eddy-mean flow interactions affect the position, strength and variations of mean currents and eddies are important drivers of oceanic heat transport and atmosphere-ocean-coupling. However, simulations at eddy-permitting resolutions are substantially underestimating eddy variability and eddy kinetic energy many times over. Such eddy-permitting simulations will be in use for years to come, both in coupled and uncoupled climate simulations. We present a set of kinetic energy backscatter schemes with different complexity as alternative momentum closures that can alleviate some eddy related biases such as biases in the mean currents, in sea surface height variability and in temperature and salinity. The complexity of the schemes reflects in their computational costs, the related simulation improvements and their adaptability to different resolutions. However, all schemes outperform classical viscous closures and are computationally less expensive than a related necessary resolution increase to achieve similar results. While the backscatter schemes are implemented in the ocean model FESOM2, the concepts can be adjusted to any ocean model including NEMO.</p>

scholarly journals On the Role of Asymmetric Convective Bursts to the Problem of Hurricane Intensification: Radiation of Vortex Rossby Waves and Wave–Mean Flow Interactions

2014 ◽  
Vol 71 (6) ◽  
pp. 2057-2077 ◽  
Author(s):  
Konstantinos Menelaou ◽  
M. K. Yau
Keyword(s):  
Kinetic Energy ◽  
Thermal Anomaly ◽  
Eddy Kinetic Energy ◽  
Intensity Change ◽  
Mean Flow ◽  
Symmetric Flow ◽  
Thermal Forcing ◽  
Sensitivity Experiments ◽  
Flow Interactions

Abstract The role of asymmetric convection to the intensity change of a weak vortex is investigated with the aid of a “dry” thermally forced model. Numerical experiments are conducted, starting with a weak vortex forced by a localized thermal anomaly. The concept of wave activity, the Eliassen–Palm flux, and eddy kinetic energy are then applied to identify the nature of the dominant generated waves and to diagnose their kinematics, structure, and impact on the primary vortex. The physical reasons for which disagreements with previous studies exist are also investigated utilizing the governing equation for potential vorticity (PV) perturbations and a number of sensitivity experiments. From the control experiment, it is found that the response of the vortex is dominated by the radiation of a damped sheared vortex Rossby wave (VRW) that acts to accelerate the symmetric flow through the transport of angular momentum. An increase of the kinetic energy of the symmetric flow by the VRW is shown also from the eddy kinetic energy budget. Additional tests performed on the structure and the magnitude of the initial thermal forcing confirm the robustness of the results and emphasize the significance of the wave–mean flow interaction to the intensification process. From the sensitivity experiments, it is found that for a localized thermal anomaly, regardless of the baroclinicity of the vortex and the radial and vertical gradients of the thermal forcing, the resultant PV perturbation follows a damping behavior, thus suggesting that deceleration of the vortex should not be expected.

scholarly journals Observed Storm Track Dynamics in Drake Passage

2019 ◽  
Vol 49 (3) ◽  
pp. 867-884 ◽  
Author(s):  
Annie Foppert
Keyword(s):  
Mean Field ◽  
Storm Track ◽  
Drake Passage ◽  
Polar Front ◽  
Mean Flow ◽  
Track Dynamics ◽  
Flow Interactions ◽  
Circumpolar Current ◽  
Eddy Potential Energy ◽  
Shackleton Fracture Zone

AbstractThe dynamics of an oceanic storm track—where energy and enstrophy transfer between the mean flow and eddies—are investigated using observations from an eddy-rich region of the Antarctic Circumpolar Current downstream of the Shackleton Fracture Zone (SFZ) in Drake Passage. Four years of measurements by an array of current- and pressure-recording inverted echo sounders deployed between November 2007 and November 2011 are used to diagnose eddy–mean flow interactions and provide insight into physical mechanisms for these transfers. Averaged within the upper to mid-water column (400–1000-m depth) and over the 4-yr-record mean field, eddy potential energy is highest in the western part of the storm track and maximum eddy kinetic energy occurs farther away from the SFZ, shifting the proportion of eddy energies from to about 1 along the storm track. There are enhanced mean 3D wave activity fluxes immediately downstream of SFZ with strong horizontal flux vectors emanating northeast from this region. Similar patterns across composites of Polar Front and Subantarctic Front meander intrusions suggest the dynamics are set more so by the presence of the SFZ than by the eddy’s sign. A case study showing the evolution of a single eddy event, from 15 to 23 July 2010, highlights the storm-track dynamics in a series of snapshots. Consistently, explaining the eddy energetics pattern requires both horizontal and vertical components of W, implying the importance of barotropic and baroclinic processes and instabilities in controlling storm-track dynamics in Drake Passage.

scholarly journals Nonlinear Saturation of Vertically Propagating Rossby Waves

2009 ◽  
Vol 66 (4) ◽  
pp. 915-934 ◽  
Author(s):  
Constantine Giannitsis ◽  
Richard S. Lindzen
Keyword(s):  
Wave Propagation ◽  
Channel Model ◽  
Plane Channel ◽  
Nonlinear Flow ◽  
Computational Domain ◽  
Mean Flow ◽  
Wave Interactions ◽  
Linear Solution ◽  
Wave Growth ◽  
Flow Interactions

Abstract The interaction between vertical Rossby wave propagation and wave breaking is studied in the idealized context of a beta-plane channel model. Considering the problem of propagation through a uniform zonal flow in an exponentially stratified fluid, where linear theory predicts exponential wave growth with height, the question is how wave growth is limited in the nonlinear flow. Using a numerical model, the authors examine the behavior of the flow as the bottom forcing increases through values bound to lead to a breakdown of the linear solution within the computational domain. Focusing on the equilibrium flow obtained for each value of the bottom forcing, an attempt is made to identify the mechanisms involved in limiting wave growth and examine in particular the importance of wave–wave interactions. The authors also examine the case in which forcing is continuously increasing with time so as to enhance effects peculiar to transiency; it does not significantly alter the main results. Wave–mean flow interactions are found to dominate the dynamics even for strong bottom forcing values. Ultimately, it is the modification of the mean flow that is found to limit the vertical penetration of the forced wave, through either increased wave absorption or downward reflection. Linear propagation theory is found to capture the wave structure surprisingly well, even when the total flow is highly deformed. Overall, the numerical results seem to suggest that wave–wave interactions do not have a strong direct effect on the propagating disturbance. Wave–mean flow interactions limit wave growth sufficiently that a strong additional nonlinear enstrophy sink, through downscale cascade, is not necessary. Quantitatively, however, wave–wave interactions, primarily among the lowest wavenumbers, prove important so as to sufficiently accurately determine the basic state and its influence on wave propagation.

A Diagnostic Study of Eddy-Mean Flow Interactions during FGGE SOP-1

1985 ◽  
Vol 42 (17) ◽  
pp. 1838-1845 ◽  
Author(s):  
Mark P. Baldwin ◽  
H. J. Edmon ◽  
James R. Holton
Keyword(s):  
Diagnostic Study ◽  
Mean Flow ◽  
Flow Interactions

A climatological study of transient-mean-flow interactions over West Africa

2009 ◽  
Vol 136 (S1) ◽  
pp. 397-410 ◽  
Author(s):  
Stephanie Leroux ◽  
Nicholas M. J. Hall ◽  
George N. Kiladis
Keyword(s):  
West Africa ◽  
Mean Flow ◽  
Flow Interactions

scholarly journals Intra-seasonal Oscillations (ISO) of zonal-mean meridional winds and temperatures as measured by UARS

2005 ◽  
Vol 23 (4) ◽  
pp. 1131-1137 ◽  
Author(s):  
F. T. Huang ◽  
H. G. Mayr ◽  
C. A. Reber
Keyword(s):  
Meridional Wind ◽  
Mean Flow ◽  
Independent Evidence ◽  
Doppler Imager ◽  
Temperature Oscillations ◽  
Low Latitudes ◽  
Meridional Winds ◽  
Flow Interactions ◽  
Phase Variations ◽  
Seasonal Oscillations

Abstract. Based on an empirical analysis of measurements with the High Resolution Doppler Imager (HRDI) on the UARS spacecraft in the upper mesosphere (95km), persistent and regular intra-seasonal oscillations (ISO) with periods of about 2 to 4 months have recently been reported in the zonal-mean meridional winds. Similar oscillations have also been discussed independently in a modeling study, and they were attributed to wave-mean-flow interactions. The observed and modeled meridional wind ISOs were largely confined to low latitudes. We report here on an analysis of concurrent UARS temperature measurements, which produces oscillations similar to those seen in the meridional winds. Although the temperature oscillations are observed at lower altitudes (55km), their phase variations with latitude are qualitatively consistent with the inferred properties seen in the meridional winds and thus provide independent evidence for the existence of ISOs in the mesosphere.

Barotropic and Baroclinic Eddy Feedbacks in the Midlatitude Jet Variability and Responses to Climate Change–Like Thermal Forcings

2016 ◽  
Vol 74 (1) ◽  
pp. 111-132 ◽  
Author(s):  
D. Alex Burrows ◽  
Gang Chen ◽  
Lantao Sun
Keyword(s):  
Climate Change ◽  
Time Scale ◽  
Climate Models ◽  
Atmospheric Model ◽  
Finite Amplitude ◽  
Mean Flow ◽  
Annular Mode ◽  
Flow Interactions ◽  
Jet Variability ◽  
Vertically Propagating

Abstract Studies have suggested that the persistence in the meridional vacillation of the midlatitude jet (i.e., annular mode time scale) in comprehensive climate models is related to the model biases in climatological jet latitude, with important implications for projections of future climates and midlatitude weather events. Through the use of the recently developed finite-amplitude wave activity formalism and feedback quantifying techniques, this paper has quantified the role of barotropic and baroclinic eddy feedbacks in annular mode time scales using an idealized dry atmospheric model. The eddy–mean flow interaction that characterizes the persistent anomalous state of the midlatitude jet depends on processes associated with the lower-tropospheric source of vertically propagating Rossby waves, baroclinic mechanisms, and processes associated with upper-tropospheric wave propagation and breaking, barotropic mechanisms. A variety of climate change–like thermal forcings are used to generate a range of meridional shifts in the midlatitude eddy-driven jet. The idealized model shows a reduction in annular mode time scale associated with an increase in jet latitude, similar to comprehensive climate models. This decrease in time scale can be attributed to a similar decrease in the strength of the barotropic eddy feedback, which, in the positive phase of the annular mode, is characterized by anomalous potential vorticity (PV) mixing on the equatorward flank of the climatological jet. The decrease in subtropical PV mixing is, in turn, associated with a stronger subtropical jet as the eddy-driven jet is more distant from the subtropics. These results highlight the importance of subtropical eddy–mean flow interactions for the persistence of an eddy-driven jet.

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