Extreme vertical drafts in the polar summer mesosphere: A super mesospheric bore?

2021 ◽  
Author(s):  
Jorge Luis Chau ◽  
Raffaele Marino ◽  
Fabio Feraco ◽  
Juan M. Urco ◽  
Gerd Baumgarten ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Extreme Event ◽  
Ice Clouds ◽  
Wind Variability ◽  
Near Space ◽  
The Earth ◽  
Radar Echoes ◽  
Gaussian Statistics ◽  
Non Gaussian ◽  
Impact Planning

<p>The polar summer mesosphere is the Earth’s coldest region, allowing the formation of mesospheric ice clouds, potentially linked to climate change. These clouds produce strong radar echoes that are used as tracers of mesospheric dynamics. Here we report the first observations of extreme vertical drafts in the mesosphere, characterized by velocities larger than 40 m/s, i.e., more than five standard deviations larger than the observed wind variability. The morphology seems to resemble mesospheric bores, however the scales observed are much larger. Powerful vertical drafts, intermittent in space and time, emerge also in direct numerical simulations of stratified flows, predicting non-Gaussian statistics of vertical velocities. This evidence suggests that mesospheric bores might result from the interplay of gravity waves and turbulent motions. Our extreme event is interpreted as a mesospheric "super-bore", impacting mesospheric mixing and ice-formation, and would potentially impact planning of sub-orbital flights, and the investigation of biological material in the near space.</p>

scholarly journals Solitons in the Close Binary Systems

1998 ◽  
Vol 11 (1) ◽  
pp. 398-398
Author(s):  
Kenji Tanabe
Keyword(s):  
Gravity Waves ◽  
Binary Systems ◽  
Kdv Equation ◽  
Frame Of Reference ◽  
Close Binary ◽  
Flare Activity ◽  
Lagrangian Point ◽  
Nls Equation ◽  
Close Binary Systems ◽  
The Earth

Propagation of the surface waves of the lobe-filing components of close binary systems is investigated theoretically. Such waves are considered to be analogous to the gravity waves of water on the earth. As a result, the equations of the surface wave in the rotating frame of reference are reduced to the so-called Kortewegde Vries (KdV) equation and non-linear Schroedinger (NLS) equation according to its ”depth”. Each of these equations is known to have the solution of soliton. When this soliton is sent to the other component of the binary system through the Lagrangian point, it can give rise to the flare activity observed in some kinds of close binary systems.

scholarly journals Observation of Kelvin–Helmholtz instabilities and gravity waves in the summer mesopause above Andenes in Northern Norway

2018 ◽  
Vol 18 (9) ◽  
pp. 6721-6732 ◽  
Author(s):  
Gunter Stober ◽  
Svenja Sommer ◽  
Carsten Schult ◽  
Ralph Latteck ◽  
Jorge L. Chau
Keyword(s):  
Gravity Waves ◽  
Middle Atmosphere ◽  
Phase Speed ◽  
Velocity Measurements ◽  
Wind Variability ◽  
Short Period ◽  
Strong Shear ◽  
Summer Echoes ◽  
Period Wave ◽  
Horizontal Wavelength

Abstract. We present observations obtained with the Middle Atmosphere Alomar Radar System (MAARSY) to investigate short-period wave-like features using polar mesospheric summer echoes (PMSEs) as a tracer for the neutral dynamics. We conducted a multibeam experiment including 67 different beam directions during a 9-day campaign in June 2013. We identified two Kelvin–Helmholtz instability (KHI) events from the signal morphology of PMSE. The MAARSY observations are complemented by collocated meteor radar wind data to determine the mesoscale gravity wave activity and the vertical structure of the wind field above the PMSE. The KHIs occurred in a strong shear flow with Richardson numbers Ri < 0.25. In addition, we observed 15 wave-like events in our MAARSY multibeam observations applying a sophisticated decomposition of the radial velocity measurements using volume velocity processing. We retrieved the horizontal wavelength, intrinsic frequency, propagation direction, and phase speed from the horizontally resolved wind variability for 15 events. These events showed horizontal wavelengths between 20 and 40 km, vertical wavelengths between 5 and 10 km, and rather high intrinsic phase speeds between 45 and 85 m s−1 with intrinsic periods of 5–10 min.

Non-Gaussian statistics of partially coherent light in atmospheric turbulence

2020 ◽  
Vol 29 (6) ◽  
pp. 064203 ◽  
Author(s):  
Hao Ni ◽  
Chunhao Liang ◽  
Fei Wang ◽  
Yahong Chen ◽  
Sergey A. Ponomarenko ◽  
...  
Keyword(s):  
Atmospheric Turbulence ◽  
Coherent Light ◽  
Partially Coherent ◽  
Partially Coherent Light ◽  
Gaussian Statistics ◽  
Non Gaussian

A resonant test-field model of gravity waves

1983 ◽  
Vol 132 ◽  
pp. 417-430 ◽  
Author(s):  
Bruce J. West
Keyword(s):  
Steady State ◽  
Gravity Waves ◽  
Planck Equation ◽  
Steady State Solution ◽  
Test Field ◽  
Statistical Fluctuations ◽  
Resonant Interactions ◽  
Energy Spectral Density ◽  
Non Gaussian ◽  
Turbulent Wind Field

In this paper we propose an ‘irreversible’ resonant test-field (RTF) model to describe the statistical fluctuations of gravity waves on deep water driven by a turbulent wind field. The non-resonant interactions in the gravity-wave Hamiltonian are replaced by a Markov process in the equation of motion for the resonantly interacting gravity waves, i.e. Hamilton's equations are replaced by a Langevin equation for the RTF waves. The RTF models the irreversible energy-transfer process by a Fokker-Planck equation for the phase-space probability density, the exact steady-state solution of which is determined to be non-Gaussian. An H-theorem for the RTF predicts the monotonic approach to the asymptotic steady state near which the transport properties of the field are studied. The steady-state energy-spectral density is calculated (in some approximation) to be k−4.

Route to non-Gaussian statistics in convective turbulence

2007 ◽  
Vol 75 (3) ◽  
Author(s):  
Roberto Festa ◽  
Andrea Mazzino ◽  
Marco Tizzi
Keyword(s):  
Convective Turbulence ◽  
Gaussian Statistics ◽  
Non Gaussian
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