Simulation of rough surfaces with non-Gaussian statistics

1993 ◽  
Author(s):  
Michael Litvak
Keyword(s):  
Rough Surfaces ◽  
Gaussian Statistics ◽  
Non Gaussian

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>

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

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

scholarly journals LÉVY STATISTICAL FLUCTUATIONS FROM A RANDOM AMPLIFYING MEDIUM

2006 ◽  
Vol 06 (01) ◽  
pp. L95-L101 ◽  
Author(s):  
DIVYA SHARMA ◽  
HEMA RAMACHANDRAN ◽  
N. KUMAR
Keyword(s):  
Emission Intensity ◽  
Experimental Realization ◽  
Fat Tail ◽  
Statistical Fluctuations ◽  
Gaussian Statistics ◽  
Lévy Statistics ◽  
Non Gaussian

We report our studies of emission from a dye-scatterer system, commonly known as random amplifying medium (RAM). It is found to exhibit non-Gaussian statistics of emission intensity over the ensemble of random realizations. The amplification is dominated by certain improbable events that are "larger than rare", which give the intensity statistics a Lévy-like fat tail. This, to the best of our knowledge, provides the first experimental realization of the Lévy statistics in the optics of a random amplifying medium, and the analysis thereof. Notably, the Lévy exponent is continuously tunable parametrically.

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