Comparison of measurements of the outer scale of turbulence by three different techniques

Ziad, Aziz; Schöck, Matthias; Chanan, G. A.; Troy, Mitchell; Dekany, Richard; Lane, Benjamin F.; Borgnino, J.; Martin, F.

doi:10.1364/ao.43.002316

Cited by 48 publications

(32 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In interferometry the fringe excursion is strongly dependent on the outer scale according to the telescope diameter and the baseline (Mariotti 1994;Conan et al 2000;Ziad et al 2004;Maire et al 2006). As the measured outer scale at Dome C is smaller than at mid-latitude observatories, it is, then, expected that the fringe excursion should be smaller.…”

Section: Discussionmentioning

confidence: 99%

First statistics of the turbulence outer scale at Dome C

Ziad¹,

Aristidi²,

Agabi³

et al. 2008

A&A

View full text Add to dashboard Cite

Context. The outer scale of wavefronts is of interest for the dimensioning and the optimisation of the High Angular Resolution techniques such as Interferometry and Adaptive Optics, particularly for the new generation of telescopes such as the Extremely Large Telescopes (ELT). Aims. We aim to provide the first statistics of the outer scale at Dome C site in Antarctica to finalize the characterization of this site. Methods. A new version of the Generalized Seeing Monitor has been developed for extremely cold conditions. Two DIMMs (Differential Image Motion Monitor) were coupled to extract Angle-of-Arrival (AA) fluctuations using CCD detectors. Correlations of these AA fluctuations for different baselines lead to outer scale estimations. Results. For the first time, statistics of the outer scale at Dome C are provided leading to small values in the surface layer at Dome C. These small outer scale values compared to temperate sites considerably reduce the fringe excursion of interferometers and the low orders of the normalized amplitude of atmospheric Zernike coefficients, particularly the tip-tilt. Conclusions. The Dome C small outer scale combined with the large coherence time and large isoplanatic angle are very useful for the development of Adaptive Optics systems and long-baseline interferometers.

show abstract

Section: Discussionmentioning

confidence: 99%

First statistics of the turbulence outer scale at Dome C

Ziad¹,

Aristidi²,

Agabi³

et al. 2008

A&A

View full text Add to dashboard Cite

show abstract

“…Many measurements have been made to try to estimate the magnitude of the outer scale in the atmosphere. Estimates measured at high elevation observatories for astronomical applications are in the range of tens of metres (Ziad et al 2004). Micrometeorological studies find outer scales on the order of hundreds to thousands of metres with considerable variation (Teunissen 1980;Kaimal and Finnigan 1994).…”

Section: Introductionmentioning

confidence: 99%

Turbulence Anisotropy in the Near-Surface Atmosphere and the Evaluation of Multiple Outer Length Scales

Klipp

2013

Boundary-Layer Meteorol

View full text Add to dashboard Cite

Length scales determined by maximum turbulent kinetic energy (TKE), the integral scale, and two length scales based on Reynolds stress-tensor anisotropy are compared to the often stated outer length scales of boundary-layer depth and distance from the earth's surface, z. The scales are calculated using sonic anemometer data from two elevations, 5 and 50 m above the ground at the main tower site of the CASES-99 field campaign. In general, none of these scales agrees with the other, although the scale of maximum TKE is often similar to the boundary-layer depth during daytime hours, and the length scales derived from anisotropy characteristics are sometimes similar to κz, z, and 2z depending on scale definition and thermal stability. Except for the scale with the strictest isotropy threshold, the turbulence is anisotropic for each of the various candidates for the outer scale. Length scales for maximum buoyancy flux and temperature variance are evaluated and the turbulence characteristics at these scales are almost always found to be anisotropic.

show abstract

“…This temporal structure function saturates for high values of τ, and the point at which the structure function reaches the 1 e of this maximum corresponds to the GSM τ AA (Ziad et al 2004).…”

Section: Coherence Timementioning

confidence: 97%

“…This also enabled us to validate the atmospheric model (Maire et al 2008). Two modules were placed on the same mount to measure the seeing with the DIMM method (see Ziad et al 2004). …”

Section: The Gsm (Generalized Seeing Monitor)mentioning

confidence: 99%

Multi-instrument measurement campaign at Paranal in 2007

Ali

Ziad

Berdja

et al. 2010

A&A

View full text Add to dashboard Cite

Aims. Within the framework of site qualification for the future European large telescope E-ELT, a campaign of measurements was carried out for ten nights in December 2007 at Paranal using six independent instruments. Methods. To characterize the optical turbulence, two techniques were used: the statistical analysis of the fluctuations of the angle of arrival and the scintillation of the observed objects which are, in this case, a single star for DIMM, GSM, and MASS, a double star for Cute-SCIDAR, and Moon limb for MOSP and LuSci. Results. The optical parameters measured in this campaign and presented here are the seeing, the isoplanatic angle, the coherence time, and the outer scale. We obtain a good agreement with the value measured in previous campaigns. We also extracted the vertical profile of the turbulence given by C 2 n (h), and the profiles of the outer scale for the first time at Paranal. A comparison of the different results that we present here allows the determination of the energy distribution in the free atmosphere, on the ground layer as well as in the first meters above ground. This reveals a significant contribution of the surface layer to the degradation of the global seeing.

show abstract

Comparison of measurements of the outer scale of turbulence by three different techniques

Cited by 48 publications

References 29 publications

First statistics of the turbulence outer scale at Dome C

First statistics of the turbulence outer scale at Dome C

Turbulence Anisotropy in the Near-Surface Atmosphere and the Evaluation of Multiple Outer Length Scales

Multi-instrument measurement campaign at Paranal in 2007

Contact Info

Product

Resources

About