scholarly journals A Mechanism of Ice-Band Pattern Formation Caused by Resonant Interaction between Sea Ice and Internal Waves: A Theory

2016 ◽  
Vol 46 (2) ◽  
pp. 583-600 ◽  
Author(s):  
Ryu Saiki ◽  
Humio Mitsudera
Keyword(s):  
Pattern Formation ◽  
Sea Ice ◽  
Internal Waves ◽  
Gravity Waves ◽  
Wind Direction ◽  
Propagation Direction ◽  
Band Pattern ◽  
Band Spacing ◽  
Internal Inertia ◽  
Inertia Gravity Waves

AbstractIce bands are frequently observed over marginal ice zones in polar seas. A typical ice-band pattern has a regular spacing of about 10 km and extends over 100 km in the marginal ice zone. Further, the long axis of an ice band lies to the left (right) with respect to the wind direction in the Northern (Southern) Hemisphere. Here, the study shows that the resonance between ice-band pattern propagation and internal inertia–gravity waves below the sea ice well explains the ice-band pattern formation. Internal waves are generated by the difference between the stress on the open water and the stress on ice-covered water. This in turn reinforces the formation of an ice-band pattern with a regular band spacing. Specifically, the authors have found the following: 1) A band spacing on the order of 10 km is selected by the resonance condition in which the ice-band pattern propagation speed coincides with the phase speed of internal inertia–gravity waves. 2) The ice bands tend to develop favorably when the wind direction and the band propagation direction are nearly parallel. The velocity acceleration caused by the periodic differential stress associated with the ice bands, driven by the wind parallel to the band propagation direction, is important. The wind direction may turn to the left (right) slightly in the Northern (Southern) Hemisphere as a result of the Coriolis force acting on ice. Satellite images confirmed that the band spacing of the ice-band pattern in the polar seas is consistent with this theory.

Mechanism of ice-band pattern formation caused by resonant interaction between sea ice and internal waves in a continuously stratified ocean

2021 ◽  
Vol 190 ◽  
pp. 102474
Author(s):  
Ryu Saiki ◽  
Humio Mitsudera ◽  
Ayumi Fujisaki-Manome ◽  
Noriaki Kimura ◽  
Jinro Ukita ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Sea Ice ◽  
Internal Waves ◽  
Resonant Interaction ◽  
Band Pattern ◽  
Stratified Ocean

scholarly journals Internal Inertia–Gravity Waves in the Tropical Lower Stratosphere Observed by the Arecibo Radar

1984 ◽  
Vol 41 (15) ◽  
pp. 2359-2367 ◽  
Author(s):  
Yasuyuki Maekawa ◽  
Shoichiro Fukao ◽  
Toru Sato ◽  
Susumu Kato ◽  
Ronald F. Woodman
Keyword(s):  
Gravity Waves ◽  
Lower Stratosphere ◽  
Internal Inertia ◽  
Inertia Gravity Waves

Inertia-gravity waves beyond the inertial latitude. Part 1. Inviscid singular focusing

2010 ◽  
Vol 664 ◽  
pp. 478-509 ◽  
Author(s):  
VICTOR I. SHRIRA ◽  
WILLIAM A. TOWNSEND
Keyword(s):  
Wave Field ◽  
Internal Waves ◽  
Gravity Waves ◽  
Deep Ocean ◽  
Vertical Shear ◽  
Buoyancy Frequency ◽  
Local Minima ◽  
Wave Evolution ◽  
Vertical Scales ◽  
Inertia Gravity Waves

The paper is concerned with analytical study of inertia-gravity waves in rotating density-stratified ideal fluid confined in a spherical shell. It primarily aims at clarifying the possible role of these motions in deep ocean mixing. Recently, it was found that on the ‘non-traditional’ β-plane inertia-gravity internal waves can propagate polewards beyond their inertial latitude, where the wave frequency equals the local Coriolis parameter, by turning into subinertial modes trapped in the narrowing waveguides around the local minima of buoyancy frequency N. The behaviour of characteristics was established: wave horizontal and vertical scales decrease as the wave advances polewards and tend to zero at a latitude corresponding to an attractor of characteristics. However, the basic questions about wave evolution, its quantitative description and the possibility of its reflection from the critical latitude remain open. The present work addresses these issues by studying the linear inviscid evolution of finite bandwidth wavepackets on the ‘non-traditional’ β-plane past the inertial latitude for generic oceanic stratification. Beyond the inertial latitude, the wave field is confined in narrowing waveguides of three distinct generic types around different local minima of the buoyancy frequency. In the oceanic context, the widest is adjacent to the flat bottom, the thinnest is the upper mixed layer, and the middle one is located between the seasonal and main thermocline. We find explicit asymptotic solutions describing the wave field in the WKB approximation. As a byproduct, the conservation of wave action principle is explicitly formulated for all types of internal waves on the ‘non-traditional’ β-plane. The wave velocities and vertical shear tend to infinity and become singular at the attractor latitude or its vicinity for both monochromatic and finite bandwidth packets. We call this phenomenon singular focusing. These WKB solutions are shown to remain valid up to singularity for the bottom and mid-ocean waveguides. The main conclusion is that even in the inviscid setting the wave evolution towards smaller and smaller horizontal and vertical scales is irreversible: there is no reflection. For situations typical of deep ocean, a simultaneous increase in wave amplitude and decrease of vertical scale causes a sharp increase of vertical shear, which may lead to wave breaking and increased mixing.

The Roles of Equatorial Trapped Waves and Internal Inertia–Gravity Waves in Driving the Quasi-Biennial Oscillation. Part II: Three-Dimensional Distribution of Wave Forcing

2010 ◽  
Vol 67 (4) ◽  
pp. 981-997 ◽  
Author(s):  
Yoshio Kawatani ◽  
Shingo Watanabe ◽  
Kaoru Sato ◽  
Timothy J. Dunkerton ◽  
Saburo Miyahara ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Wind Shear ◽  
Three Dimensional ◽  
Walker Circulation ◽  
Western Hemisphere ◽  
Flux Divergence ◽  
Quasi Biennial Oscillation ◽  
Wave Forcing ◽  
Internal Inertia ◽  
Inertia Gravity Waves

Abstract Three-dimensional wave forcing of simulated quasi-biennial oscillation (QBO) is investigated using a high-resolution atmospheric general circulation model with T213L256 resolution (60-km horizontal and 300-m vertical resolution). In both the eastward and westward wind shear phases of the QBO, nearly all Eliassen–Palm flux (EP flux) divergence due to internal inertia–gravity waves (defined as fluctuations with zonal wavenumber ≥12) results from the divergence of the vertical component of the flux. On the other hand, EP flux divergence due to equatorial trapped waves (EQWs) results from both the meridional and vertical components of the flux in regions of strong vertical wind shear. Longitudinal dependence of wave forcing is also investigated by three-dimensional wave activity flux applicable to gravity waves. Near the top of the Walker circulation, strong eastward (westward) wave forcing occurs in the Eastern (Western) Hemisphere due to internal inertia–gravity waves with small horizontal phase speed. In the eastward wind shear zone associated with the QBO, the eastward wave forcing due to internal inertia–gravity waves in the Eastern Hemisphere is much larger than that in the Western Hemisphere, whereas in the westward wind shear zone, westward wave forcing does not vary much in the zonal direction. Zonal variation of wave forcing in the stratosphere results from (i) zonal variation of wave sources, (ii) the vertically sheared zonal winds associated with the Walker circulation, and (iii) the phase of the QBO.

The Roles of Equatorial Trapped Waves and Internal Inertia–Gravity Waves in Driving the Quasi-Biennial Oscillation. Part I: Zonal Mean Wave Forcing

2010 ◽  
Vol 67 (4) ◽  
pp. 963-980 ◽  
Author(s):  
Yoshio Kawatani ◽  
Shingo Watanabe ◽  
Kaoru Sato ◽  
Timothy J. Dunkerton ◽  
Saburo Miyahara ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Wind Shear ◽  
Trapped Waves ◽  
Quasi Biennial Oscillation ◽  
Frequency Spectra ◽  
Wave Forcing ◽  
Zonal Wavenumber ◽  
Internal Inertia ◽  
Biennial Oscillation ◽  
Inertia Gravity Waves

Abstract The roles of equatorial trapped waves (EQWs) and internal inertia–gravity waves in driving the quasi-biennial oscillation (QBO) are investigated using a high-resolution atmospheric general circulation model with T213L256 resolution (60-km horizontal and 300-m vertical resolution) integrated for three years. The model, which does not use a gravity wave drag parameterization, simulates a QBO. Although the simulated QBO has a shorter period than that of the real atmosphere, its amplitudes and structure in the lower stratosphere are fairly realistic. The zonal wavenumber/frequency spectra of simulated outgoing longwave radiation represent realistic signals of convectively coupled EQWs. Clear signals of EQWs are also seen in the stratospheric wind components. In the eastward wind shear of the QBO, eastward EQWs including Kelvin waves contribute up to ∼25%–50% to the driving of the QBO. The peaks of eastward wave forcing associated with EQWs and internal inertia–gravity waves occur at nearly the same time at the same altitude. On the other hand, westward EQWs contribute up to ∼10% to driving the QBO during the weak westward wind phase but make almost zero contribution during the relatively strong westward wind phase. Extratropical Rossby waves propagating into the equatorial region contribute ∼10%–25%, whereas internal inertia–gravity waves with zonal wavelength ≲1000 km are the main contributors to the westward wind shear phase of the simulated QBO.

Semi-Lagrangian exponential time-integration method for the shallow water equations on the cubed sphere grid

2020 ◽  
Vol 35 (6) ◽  
pp. 355-366
Author(s):  
Vladimir V. Shashkin ◽  
Gordey S. Goyman
Keyword(s):  
Shallow Water ◽  
Gravity Waves ◽  
Shallow Water Equations ◽  
Time Integration ◽  
Standard Test ◽  
Integration Scheme ◽  
Test Problems ◽  
Cubed Sphere ◽  
Lagrangian Scheme ◽  
Inertia Gravity Waves

AbstractThis paper proposes the combination of matrix exponential method with the semi-Lagrangian approach for the time integration of shallow water equations on the sphere. The second order accuracy of the developed scheme is shown. Exponential semi-Lagrangian scheme in the combination with spatial approximation on the cubed-sphere grid is verified using the standard test problems for shallow water models. The developed scheme is as good as the conventional semi-implicit semi-Lagrangian scheme in accuracy of slowly varying flow component reproduction and significantly better in the reproduction of the fast inertia-gravity waves. The accuracy of inertia-gravity waves reproduction is close to that of the explicit time-integration scheme. The computational efficiency of the proposed exponential semi-Lagrangian scheme is somewhat lower than the efficiency of semi-implicit semi-Lagrangian scheme, but significantly higher than the efficiency of explicit, semi-implicit, and exponential Eulerian schemes.

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