Effect of the intermittent atmosphere on laser scintillations

Gozani, Joseph

doi:10.1364/ol.24.000436

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…2 Quasi-homogeneous media are characterized by the property that the strength of their scattering potential S F ͑r , ͒ at a particular frequency varies much more slowly with position than the correlation coefficient F ͑r 1 , r 2 ; ͒ϵ F ͑r 2 − r 1 ; ͒ varies with the difference rЈ = r 2 − r 1 . The troposphere, for example, is sometimes modeled as such a medium, 3 as are confined plasmas. 4 An analysis of the spectral changes produced by scattering from a quasi-homogeneous, anisotropic random medium was carried out in Ref.…”

Section: Introductionmentioning

confidence: 99%

Scattering of light from quasi-homogeneous sources by quasi-homogeneous media

2006

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The field generated by scattering of light from a quasi-homogeneous source on a quasi-homogeneous, random medium is investigated. It is found that, within the accuracy of the first-order Born approximation, the far field satisfies two reciprocity relations (sometimes called uncertainty relations). One of them implies that the spectral density (or spectral intensity) is proportional to the convolution of the spectral density of the source and the spatial Fourier transform of the correlation coefficient of the scattering potential. The other implies that the spectral degree of coherence of the far field is proportional to the convolution of the correlation coefficient of the source and the spatial Fourier transform of the strength of the scattering potential. While the case we consider might seem restrictive, it is actually quite general. For instance, the quasi-homogeneous source model can be used to describe the generation of beams with different coherence properties and different angular spreads. In addition, the quasi-homogeneous scattering model adequately describes a wide class of turbulent media, including a stratified, turbulent atmosphere and confined plasmas.

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Section: Introductionmentioning

confidence: 99%

Scattering of light from quasi-homogeneous sources by quasi-homogeneous media

2006

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“…Other studies have explicitly considered global intermittency effects on wave propagation, or provide treatments for intermittency effects that are not specifically global or intrinsic. [21][22][23][24][25][26][27] In these studies, it is generally assumed that the length of the propagation path is large compared to the outer scale. Hence, the fluctuations in C n 2 resulting from intrinsic intermittency are unimportant.…”

Section: Introductionmentioning

confidence: 99%

Sound-wave coherence in atmospheric turbulence with intrinsic and global intermittency

Wilson

Ostashev

Goedecke

2008

The Journal of the Acoustical Society of America

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The coherence function of sound waves propagating through an intermittently turbulent atmosphere is calculated theoretically. Intermittency mechanisms due to both the turbulent energy cascade (intrinsic intermittency) and spatially uneven production (global intermittency) are modeled using ensembles of quasiwavelets (QWs), which are analogous to turbulent eddies. The intrinsic intermittency is associated with decreasing spatial density (packing fraction) of the QWs with decreasing size. Global intermittency is introduced by allowing the local strength of the turbulence, as manifested by the amplitudes of the QWs, to vary in space according to superimposed Markov processes. The resulting turbulence spectrum is then used to evaluate the coherence function of a plane sound wave undergoing line-of-sight propagation. Predictions are made by a general simulation method and by an analytical derivation valid in the limit of Gaussian fluctuations in signal phase. It is shown that the average coherence function increases as a result of both intrinsic and global intermittency. When global intermittency is very strong, signal phase fluctuations become highly non-Gaussian and the average coherence is dominated by episodes with weak turbulence.

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“…Such fine-wire sensors were used with a kite/tetheredblimp platform for the optical and mechanical turbulence results presented in this paper. [7][8][9][10][11][12] Mahrt showed the importance to make the distinction between small scale and global intermittency. Observations from the different systems included those from optical devices ͑a stellar scintillometer, an isoplanometer, and a transverse coherence length system͒, a very high frequency ͑VHF͒ radar from which C n 2 was derived from Bragg scatter at turbulent scales, and fine-wire sensors providing C T 2 from which C n 2 was calculated.…”

Section: Introductionmentioning

confidence: 99%

Turbulence observations over a desert basin using a kite/tethered-blimp platform

et al. 2000

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Results of the (temperature) refractive index structure parameter (C T 2 ), C n 2 , and the eddy dissipation rate ⑀ derived from the velocity structure parameter C v 2 are presented from fast response sensor observations using a kite/tethered-blimp platform in the Tularosa Basin at White Sands Missile Range, New Mexico, during the spring of 1998. Comparisons of different sensors (fine-wire probes and pitot tubes) measuring the same parameter are displayed and discussed while salient features of all sensors (standard and fast response) and the kite and tethered-blimp platforms are outlined. The nature and statistics of turbulence, including intermittency, under different stability conditions is discussed, including those found in the residual layer above the nocturnal boundary layer and the entrainment zone at the top of the daytime planetary boundary layer. In addition to displaying time series of temperature C n 2 and ⑀ results obtained at specific altitudes and times, histograms of all daytime and nighttime C n 2 and ⑀ values are compared to log-normal distributions. Examples of profiles of C n 2 and ⑀ for daytime, near sunset, and nighttime conditions are shown and discussed. The relationship of C n 2 with ⑀ is displayed for all data as well as sorted by daytime and nighttime. These results are explained in terms of potential and kinetic energy considerations under different atmospheric stability conditions.

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Effect of the intermittent atmosphere on laser scintillations

Cited by 5 publications

References 14 publications

Scattering of light from quasi-homogeneous sources by quasi-homogeneous media

Scattering of light from quasi-homogeneous sources by quasi-homogeneous media

Sound-wave coherence in atmospheric turbulence with intrinsic and global intermittency

Turbulence observations over a desert basin using a kite/tethered-blimp platform

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