Global rate and spectral characteristics of internal gravity wave generation by geostrophic flow over topography

2011 ◽  
Vol 116 (C9) ◽  
Author(s):  
R. B. Scott ◽  
J. A. Goff ◽  
A. C. Naveira Garabato ◽  
A. J. G. Nurser
Keyword(s):  
Gravity Wave ◽  
Spectral Characteristics ◽  
Internal Gravity Wave ◽  
Wave Generation ◽  
Geostrophic Flow ◽  
Global Rate ◽  
Flow Over Topography

scholarly journals Global Characterization of the Ocean’s Internal Wave Spectrum

2020 ◽  
Vol 50 (7) ◽  
pp. 1871-1891 ◽  
Author(s):  
Friederike Pollmann
Keyword(s):  
Internal Wave ◽  
Gravity Wave ◽  
Spectral Characteristics ◽  
Wave Spectrum ◽  
Internal Gravity Wave ◽  
Ocean Dynamics ◽  
Small Scale ◽  
Northwest Pacific ◽  
Spatial And Temporal Variability ◽  
Spectral Parameters

AbstractA key ingredient of energetically consistent ocean models is the parameterized link between small-scale turbulent mixing, an important energy source of large-scale ocean dynamics, and internal gravity wave energetics. Theory suggests that this link depends on the wave field’s spectral characteristics, but because of the paucity of suitable observations, its parameterization typically relies on a model spectrum [Garrett–Munk (GM)] with constant parameters. Building on the so-called “finestructure method,” internal gravity wave spectra are derived from vertical strain profiles obtained from Argo floats to provide a global estimate of the spatial and temporal variability of the GM model’s spectral parameters. For spectral slopes and wavenumber scales, the highest variability and the strongest deviation from the model’s canonical parameters are observed in the North Atlantic, the northwest Pacific, and the Southern Ocean. Internal wave energy levels in the upper ocean are well represented by the GM model value equatorward of approximately 50°, while they are up to two orders of magnitude lower poleward of this latitude. The use of variable spectral parameters in the energy level calculation hides the seasonal cycle in the northwest Pacific that was previously observed for constant parameters. The global estimates of how the GM model’s spectral parameters vary in space and time are hence expected to add relevant detail to various studies on oceanic internal gravity waves, deepening the understanding of their energetics and improving parameterizations of the mixing they induce.

Gravity Wave Generation around the Polar Vortex in the Stratosphere Revealed by 3-Hourly Radiosonde Observations at Syowa Station

2008 ◽  
Vol 65 (12) ◽  
pp. 3719-3735 ◽  
Author(s):  
Kaoru Sato ◽  
Motoyoshi Yoshiki
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Packets ◽  
Spectral Characteristics ◽  
Wave Generation ◽  
Observation Data ◽  
Energy Propagation ◽  
Syowa Station ◽  
Frequency Spectra ◽  
Wide Range

Abstract Intensive radiosonde observations were performed at Syowa Station (69.0°S, 39.6°E) over about 10 days in each of March, June, October, and December 2002 to examine inertia–gravity wave characteristics in the Antarctic lower stratosphere. Based on the 3-hourly observation data, two-dimensional (i.e., vertical wavenumber versus frequency) spectra of wind fluctuations were examined, utilizing a double Fourier transform method. Clear signals of gravity waves whose phases propagate upward, suggesting downward energy propagation, are detected in June and October when the polar night jet (PNJ) was present. On the other hand, downward phase propagation (i.e., upward energy propagation) components are dominant in all months. There is a spectral peak around the inertial frequency in a wide range of vertical wavenumbers in December when the background wind was weak, whereas large spectral densities are distributed over lower-frequency regions in June and October. These spectral characteristics are consistent with the results obtained using a gravity wave–resolving global circulation model (GCM) by Sato et al. Dynamical characteristics are examined separately for upward- and downward-propagating gravity waves in June, using a hodograph analysis method. As a result, it is found that upward- and downward-propagating wave packets observed simultaneously in the same height regions have similar horizontal wavelengths and phase velocities. This fact suggests that these gravity waves are generated from the same source with a similar mechanism. When the wave packets were observed, both the local Rossby number and the residual in the nonlinear balance equation estimated using NCEP–NCAR reanalysis data are large around the PNJ situated slightly to the lower latitudes of Syowa Station. Therefore, it is likely that the observed inertia–gravity waves are generated by a spontaneous adjustment around the geostrophically unbalanced PNJ and propagate toward Syowa Station. The possibility of spontaneous gravity wave generation around the PNJ is confirmed by comparison with the GCM simulation by Sato et al.

scholarly journals Gravity wave generation by convection and momentum deposition in the mesosphere-lower thermosphere

2013 ◽  
Vol 118 (12) ◽  
pp. 6233-6245 ◽  
Author(s):  
R. A. Vincent ◽  
M. J. Alexander ◽  
B. K. Dolman ◽  
A. D. MacKinnon ◽  
P. T. May ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Lower Thermosphere ◽  
Wave Generation
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