Direct Evidence of “Sheets” in the Atmospheric Temperature Field

Dalaudier, Francis; Sidi, Claude; Crochet, M.; Vernin, J.

doi:10.1175/1520-0469(1994)051<0237:deoita>2.0.co;2

Cited by 190 publications

(125 citation statements)

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“…Two common models for this e ect invoke either anisotropic turbulence, or partial re¯ection from the thin, stable horizontal layers which have been observed in temperature measurements from balloon soundings with high vertical resolution (e.g. Dalaudier et al, 1994;Luce et al, 1995). The latter study suggests that partial re¯ection from these layers may be the dominant source of radar returns in a vertical beam.…”

Section: Introductionmentioning

confidence: 97%

“…However, with a Doppler-beam-swinging (DBS) system such as the Aberystwyth MST radar, direct measurements of these tilt angles are not available. In-situ measurements of temperature structure by Dalaudier et al (1994) also report some evidence that the layers or sheets' are tilted, although the horizontal extent of their measurements was limited.…”

Section: Introductionmentioning

confidence: 99%

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Long-period unstable gravity-waves and associated VHF radar echoes

Worthington

Thomas

1997

Ann. Geophys.

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Abstract. VHF atmospheric radar is used to measure the wind velocity and radar echo power related to longperiod wind perturbations, including gravity waves, which are observed commonly in the lower stratosphere and tropopause region, and sometimes in the troposphere. These wind structures have been identi®ed previously as either inertia-gravity waves, often associated with jet streams, or mountain waves. At heights of peak wind shear, imbalances are found between the echo powers of a symmetric pair of radar beams, which are expected to be equal. The largest of these power di erences are found for conditions of simultaneous high wind shear and high aspect sensitivity. It is suggested that the e ect might arise from tilted specular re¯ectors or anisotropic turbulent scatterers, a result of, for example, Kelvin-Helmholtz instabilities generated by the strong wind shears. This radar power-di erence e ect could o er information about the onset of saturation in long-period waves, and the formation of thin layers of turbulence.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Long-period unstable gravity-waves and associated VHF radar echoes

Worthington

Thomas

1997

Ann. Geophys.

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“…Propagation phenomena of light beams and radio waves in the atmosphere are for example strongly influenced both by the magnitude and the spatial distribution of small-scale temperature gradients [2]. Their dynamical properties have been a subject of very accurate experimental investigations carried out in the last few years both in the atmosphere [2,3], in the ocean [4,5] and for laboratory turbulent flow [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…In the atmosphere, "ramp-and-cliff" structures in the temperature field extend from the ground to the middle stratosphere [2]. They are of major importance for the ubiquitous stratospheric radar echoes [10] and the problem of their formation is known as frontogenesis [11].…”

Section: Introductionmentioning

confidence: 99%

Fronts in passive scalar turbulence

Celani¹,

Lanotte

Mazzino³

et al. 2001

Physics of Fluids

100

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The evolution of scalar fields transported by turbulent flow is characterized by the presence of fronts, which rule the small-scale statistics of scalar fluctuations. With the aid of numerical simulations, it is shown that : isotropy is not recovered, in the classical sense, at small scales; scaling exponents are universal with respect to the scalar injection mechanisms ; high-order exponents saturate to a constant value ; non-mature fronts dominate the statistics of intense fluctuations. Results on the statistics inside the "plateaux", where fluctuations are weak, are also presented. Finally, we analyze the statistics of scalar dissipation and scalar fluxes.

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“…It is well known (Dalaudier et al 1994;Marks et al 1996;Marks et al 1999) that the optical turbulence (C 2 N ) is concentrated, with respect to the vertical direction, in thin layers placed at different altitudes in the troposphere (up to ∼20 km) and having a vertical size of some tens of meters. Such a structure is resolved by instruments such as those carried aboard the balloons that have a resolution of some meters.…”

Section: Introductionmentioning

confidence: 99%

First evidence of the finite horizontal extent of the optical turbulence layers. Implications for new adaptive optics techniques

Masciadri

Ávila

Sánchez

2002

A&A

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profiles measured (almost simultaneously) by a GS along different lines of sight. The results of this study show that (1) the horizontal size of the turbulent layers can be finite, (2) the simulations and the measurements are well correlated and (3) for the first time, we show that the model can reproduce observed seeing values that vary as much as 0.50 during the same night. This definitely shows that the numerical simulations are a useful tool in the context of the turbulence characterization for astronomical applications. Finally, we discuss the implications that a finite horizontal size of the turbulent layers could have on new adaptive optics techniques, particularly in applications to the extremely large size telescopes.

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Direct Evidence of “Sheets” in the Atmospheric Temperature Field

Cited by 190 publications

References 0 publications

Long-period unstable gravity-waves and associated VHF radar echoes

Long-period unstable gravity-waves and associated VHF radar echoes

Fronts in passive scalar turbulence

First evidence of the finite horizontal extent of the optical turbulence layers. Implications for new adaptive optics techniques

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