Determination of the turbulence parameters from fading radio-reflections from meteor trails. II

1975 ◽  
Vol 18 (3) ◽  
pp. 233-238
Author(s):  
G. M. Teptin ◽  
A. N. Fakhrutdinova
Keyword(s):  
Meteor Trails ◽  
Turbulence Parameters

THE DISTRIBUTION OF IONIZATION ALONG UNDERDENSE METEOR TRAILS

1964 ◽  
Vol 42 (11) ◽  
pp. 2035-2047 ◽  
Author(s):  
D. W. Rice ◽  
P. A. Forsyth
Keyword(s):  
Upper Atmosphere ◽  
Sources Of Error ◽  
Signal Characteristics ◽  
Radio Signals ◽  
Meteor Trails

Attempts to use the decay of radio signals reflected from individual meteor trails to study the upper atmosphere have revealed a puzzling inconsistency in the signal behavior. An earlier paper pointed out that this inconsistency remained even when the previously postulated sources of error were eliminated. As a result, an irregularly ionized trail model was proposed and shown, by calculation of signal characteristics, to be capable of accounting for the observations. This paper presents results of a new experiment which permitted the determination of the ionization profiles as the meteor trails were formed. The predicted irregularities were found, even for trails which exhibited apparently "ideal" underdense signal characteristics.

scholarly journals Direct Numerical Simulation Guidance for Thorpe Analysis to Obtain Quantitatively Reliable Turbulence Parameters

2019 ◽  
Vol 36 (11) ◽  
pp. 2247-2255
Author(s):  
Ling Wang ◽  
Marvin A. Geller ◽  
David C. Fritts
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Direct Numerical Simulation ◽  
Gravity Wave ◽  
Vertical Wavelength ◽  
Ozmidov Scale ◽  
Thorpe Scale ◽  
Individual Profiles ◽  
Turbulence Parameters

AbstractThorpe analysis has been used to study turbulence in the atmosphere and ocean. It is clear that Thorpe analysis applied to individual soundings cannot be expected to give quantitatively reliable measurements of turbulence parameters because of the instantaneous nature of the measurement. A critical aspect of this analysis is the assumption of the linear relationship C = LO/LT between the Thorpe scale LT, derived from the sounding measurements, and the Ozmidov scale LO. It is the determination of LO that enables determination of the dissipation rate of turbulence kinetic energy ε. Single atmospheric and oceanic soundings cannot indicate either the source of turbulence or the stage of its evolution; different values of C are expected for different turbulence sources and stages of the turbulence evolution and thus cannot be expected to yield quantitatively reliable turbulence parameters from individual profiles. The variation of C with the stage of turbulence evolution is illustrated for direct numerical simulation (DNS) results for gravity wave breaking. Results from a DNS model of multiscale initiation and evolution of turbulence with a Reynolds number Re (which is defined using the vertical wavelength of the primary gravity wave and background buoyancy period as length and time scales, respectively) of 100 000 are sampled as in sounding of the atmosphere and ocean, and various averaging of the sounding results indicates a convergence to a well-defined value of C, indicating that applying Thorpe analysis to atmospheric or oceanic soundings and averaging over a number of profiles gives more reliable turbulence determinations. The same averaging study is also carried out when the DNS-modeled turbulence is dominated by turbulence growing from the initial instabilities, when the turbulence is fully developed, when the modeled turbulence is decaying, and when the turbulence is in a still-later decaying stage. These individual cases converge to well defined values of C, but these values of C show a large variation resulting from the different stages of turbulence evolution. This study gives guidance as to the accuracy of Thorpe analysis of turbulence as a function of the number of profiles being averaged. It also suggests that the values of C in different environments likely depend on the dominant turbulence initiation mechanisms and on the Reynolds number of the environment.

scholarly journals Determination of the optical turbulence parameters from the adaptive optics telemetry: critical analysis and on-sky validation

2018 ◽  
Vol 57 (27) ◽  
pp. 7837 ◽  
Author(s):  
Laurent Jolissaint ◽  
Sam Ragland ◽  
Julian Christou ◽  
Peter Wizinowich
Keyword(s):  
Adaptive Optics ◽  
Critical Analysis ◽  
Optical Turbulence ◽  
Turbulence Parameters

THE DETERMINATION OF METEOR MASS DISTRIBUTION FROM RADAR ECHO COUNTS

1966 ◽  
Vol 44 (11) ◽  
pp. 2729-2748 ◽  
Author(s):  
B. A. McIntosh
Keyword(s):  
Mass Distribution ◽  
Electron Attachment ◽  
Meteor Radar ◽  
Low Velocity ◽  
Wide Beam ◽  
Radar Echoes ◽  
Long Duration ◽  
Radar Echo ◽  
Meteor Trails

In relating the frequency distribution of the durations of radar echoes from meteor trails to the mass distribution of the meteoroid flux, two major effects must be taken into account. Because bright meteors tend to be observable by radar from any angle, the rate of long-duration echoes is enhanced relative to short-duration echoes. This effect is particularly pronounced for the Ottawa radar which has wide-beam antennas. On the other hand, the effect of electron attachment is to suppress the long-duration echo count, particularly for low-velocity meteors, which produce ionized trails at lower altitudes.The influence of both these effects on the observational results from the Ottawa meteor radar is examined quantitatively.

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