scholarly journals Observations of Stratospheric Gravity Waves Over Europe on 12 January 2016: The Role of the Polar Night Jet

2020 ◽  
Vol 125 (21) ◽  
Author(s):  
Katrina Bossert ◽  
Sharon L. Vadas ◽  
Lars Hoffmann ◽  
Erich Becker ◽  
V. Lynn Harvey ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Polar Night

scholarly journals The role of constant vorticity on weakly nonlinear surface gravity waves

Wave Motion ◽  
2020 ◽  
pp. 102702
Author(s):  
M.A. Manna ◽  
S. Noubissie ◽  
J. Touboul ◽  
B. Simon ◽  
R.A. Kraenkel
Keyword(s):  
Gravity Waves ◽  
Surface Gravity ◽  
Weakly Nonlinear ◽  
Surface Gravity Waves ◽  
Constant Vorticity ◽  
Nonlinear Surface

Uniformly travelling water waves from a dynamical systems viewpoint: some insights into bifurcations from Stokes’ family

1992 ◽  
Vol 241 ◽  
pp. 333-347 ◽  
Author(s):  
C. Baesens ◽  
R. S. Mackay
Keyword(s):  
Gravity Waves ◽  
Water Waves ◽  
Travelling Waves ◽  
Hamiltonian Formulation ◽  
Inviscid Fluid ◽  
Centre Manifold ◽  
Numerical Work ◽  
Bifurcation Tree ◽  
Area Preserving

Numerical work of many people on the bifurcations of uniformly travelling water waves (two-dimensional irrotational gravity waves on inviscid fluid of infinite depth) suggests that uniformly travelling water waves have a reversible Hamiltonian formulation, where the role of time is played by horizontal position in the wave frame. In this paper such a formulation is presented. Based on this viewpoint, some insights are given into bifurcations from Stokes’ family of periodic waves. It is demonstrated numerically that there is a ‘fold point’ at amplitude A0 ≈ 0.40222. Assuming non-degeneracy of the fold and existence of an associated centre manifold, this explains why a sequence of p/q-bifurcations occurs on one side of A0, with 0 < p/q [les ] ½, in the order of the rationals. Secondly, it explains why no symmetry-breaking bifurcation is observed at A0, contrary to the expectations of some. Thirdly, it explains why the bifurcation tree for periodic uniformly travelling waves looks so much like that for the area-preserving Hénon map. Fourthly, it leads to predictions of a rich variety of spatially quasi-periodic, heteroclinic and chaotic waves.

scholarly journals On the role of dust storms in triggering atmospheric gravity waves observed in the middle atmosphere

2011 ◽  
Vol 29 (9) ◽  
pp. 1647-1654 ◽  
Author(s):  
S. K. Das ◽  
A. Taori ◽  
A. Jayaraman
Keyword(s):  
Gravity Waves ◽  
Dust Storm ◽  
Hot Spots ◽  
Middle Atmosphere ◽  
Thermal Structure ◽  
Dust Storms ◽  
Storm Events ◽  
Atmospheric Perturbations ◽  
Atmospheric Gravity

Abstract. Lower atmospheric perturbations often produce measurable effects in the middle and upper atmosphere. The present study demonstrates the response of the middle atmospheric thermal structure to the significant enhancement of the lower atmospheric heating effect caused by dust storms observed over the Thar Desert, India. Our study from multi-satellite observations of two dust storm events that occurred on 3 and 8 May 2007 suggests that dust storm events produce substantial changes in the lower atmospheric temperatures as hot spots which can become sources for gravity waves observed in the middle atmosphere.

Stratospheric mountain waves trailing across northern Europe

2021 ◽  
Author(s):  
Andreas Dörnbrack
Keyword(s):  
Gravity Waves ◽  
Polar Vortex ◽  
Internal Gravity Waves ◽  
Polar Front ◽  
Northern Europe ◽  
Polar Night ◽  
Stratospheric Polar Vortex ◽  
Mountain Waves ◽  
Almost All

&lt;table&gt;&lt;tbody&gt;&lt;tr&gt;&lt;td&gt; &lt;p&gt;&lt;span&gt;Planetary waves disturbed the hitherto stable Arctic stratospheric polar vortex mid of&lt;br&gt;January 2016 in such a way that unique tropospheric and stratospheric flow conditions&lt;br&gt;for vertically and horizontally propagating mountain waves developed. Co-existing&lt;br&gt;strong low-level westerly winds across almost all European mountain ranges plus the&lt;br&gt;almost zonally-aligned polar front jet created these favorable conditions for deeply&lt;br&gt;propagating gravity waves. Furthermore, the northward displacement of the polar night&lt;br&gt;jet resulted in a wide-spread coverage of stratospheric mountain waves trailling across&lt;br&gt;northern Europe. This paper describes the particular meteorological setting by&lt;br&gt;analyzing the tropospheric and stratospheric flows based on the ERA5 data. The&lt;br&gt;potential of the flow for exciting internal gravity waves from non-orographic sources is&lt;br&gt;evaluated across all altitudes by considering various instability indices as &amp;#948; , Ro, Ro &amp;#950; , Ro&lt;sub&gt;&amp;#8869;&lt;/sub&gt; ,&lt;br&gt;and &amp;#916; NBE&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;The analyzed gravity waves are described and characterized in terms of&lt;br&gt;commonly used parameters. The main finding of this case study is the exceptionally&lt;br&gt;vast extension of the mountain waves trailing to high latitudes originating from the flow&lt;br&gt;across the mountainous sources that are located at about 45 N. As a useful addition to&lt;br&gt;the case study, tracks for potential research flights are proposed that sample the&lt;br&gt;waves by a vertically pointing airborne remote-sensing instrument. Benefits and&lt;br&gt;drawbacks of the different approaches to observe the meridional focussing of the&lt;br&gt;mountain waves into the polar night jet are discussed.&lt;/span&gt;&lt;/p&gt; &lt;/td&gt; &lt;/tr&gt;&lt;/tbody&gt;&lt;/table&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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