Statistics of atmospheric turbulence at Cerro Pachon using the GeMS profiler

Rodriguez, Ignacio; Neichel, Benoît; Béchet, Clementine; Guzmán, Dani; Guesalaga, Andrés

doi:10.1117/12.2056665

Cited by 3 publications

(3 citation statements)

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“…The method has also been modified to include multiple LGS-WFSs and the handling of the cone and fratricide effects in the GeMS configuration. 1,29 The method has also been extended to the ESO Adaptive Optics Facility (AOF -see Valenzuela et al 30 ) and being used to derive statistical information about Cerro Pachón turbulence (see Rodriguez et al 31 ).…”

Section: N and Wind Profile Measurements With Gemsmentioning

confidence: 99%

Towards a reliability assessment of the C²_Nand wind speed vertical profiles retrieved from GeMS

et al. 2014

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The advent of a new generation of Adaptive Optics systems called Wide Field AO (WFAO) mark the beginning of a new era. By using multiple Guide Stars (GSs), either Laser Guide Stars (LGSs) or Natural Guide Stars (NGSs), WFAO significantly increases the field of view of the AO-corrected images, and the fraction of the sky that can benefit from such correction. Different typologies of WFAO have been studied over the past years. They all require multiple GSs to perform a tomographic analysis of the atmospheric turbulence. One of the fundamental aspects of the new WFAO systems is the knowledge of the spatio-temporal distribution of the turbulence above the telescope. One way to get to this information is to use the telemetry data provided by the WFAO system itself. Indeed, it has been demonstrated that WFAO systems allows one to derive the C 2 N and wind profile in the main turbulence layers (see e.g. Cortes et al. 2012 1 ). This method has the evident advantage to provide information on the turbulence stratification that effectively affects the AO system, property more difficultly respected by independently vertical profilers. In this paper, we compare the wind speeds profiles of GeMS with those predicted by a non-hydrostatical mesoscale atmospherical model (Meso-NH). It has been proved (Masciadri et al., 2013 2 ), indeed, that this model is able to provide reliable wind speed profiles on the whole troposphere and stratosphere (up to 20-25 km) above top-level astronomical sites. Correlation with measurements revealed to be very satisfactory when the model performances are analyzed from a statistical point of view as well on individual nights. Such a system appears therefore as an interesting reference to be used to quantify the GeMS wind speed profiles reliability.

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Section: N and Wind Profile Measurements With Gemsmentioning

confidence: 99%

Towards a reliability assessment of the C²_Nand wind speed vertical profiles retrieved from GeMS

et al. 2014

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“…The two methods considered here have already been successfully used on GeMS telemetry recorded during the 2011, 2012 and 2013 campaigns. 4,7,8 A statistical analysis of the results 8 and a comparison with profiles simultaneously obtained by a MASS and a DIMM 9 are tackled in two companion papers.…”

Section: Introductionmentioning

confidence: 99%

Turbulence profiling methods applied to ESO's adaptive optics facility

Valenzuela¹,

Béchet

García-Rissmann

et al. 2014

SPIE Proceedings

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Two algorithms were recently studied for C 2 n profiling from wide-field Adaptive Optics (AO) measurements on GeMS (Gemini Multi-Conjugate AO system). They both rely on the Slope Detection and Ranging (SLODAR) approach, using spatial covariances of the measurements issued from various wavefront sensors. The first algorithm estimates the C 2 n profile by applying the truncated least-squares inverse of a matrix modeling the response of slopes covariances to various turbulent layer heights. In the second method, the profile is estimated by deconvolution of these spatial cross-covariances of slopes. We compare these methods in the new configuration of ESO Adaptive Optics Facility (AOF), a high-order multiple laser system under integration. For this, we use measurements simulated by the AO cluster of ESO. The impact of the measurement noise and of the outer scale of the atmospheric turbulence is analyzed. The important influence of the outer scale on the results leads to the development of a new step for outer scale fitting included in each algorithm. This increases the reliability and robustness of the turbulence strength and profile estimations.

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“…However, this approach assumes similar power spectral density throughout the atmosphere and does not include profiling. For a general perspective on profiling, see [13,30]. We also point out a method proposed by the authors in [16], where the turbulence profile is optimized as part of the atmospheric tomography problem.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric turbulence profiling with unknown power spectral density

et al. 2018

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Adaptive optics (AO) is a technology in modern ground-based optical telescopes to compensate for the wavefront distortions caused by atmospheric turbulence. One method that allows to retrieve information about the atmosphere from telescope data is so-called SLODAR, where the atmospheric turbulence profile is estimated based on correlation data of Shack-Hartmann wavefront measurements. This approach relies on a layered Kolmogorov turbulence model. In this article, we propose a novel extension of the SLODAR concept by including a general non-Kolmogorov turbulence layer close to the ground with an unknown power spectral density. We prove that the joint estimation problem of the turbulence profile above ground simultaneously with the unknown power spectral density at the ground is illposed and propose three numerical reconstruction methods. We demonstrate by numerical simulations that our methods lead to substantial improvements in the turbulence profile reconstruction compared to the standard SLODAR-type approach. Also, our methods can accurately locate local perturbations in non-Kolmogorov power spectral densities.

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Statistics of atmospheric turbulence at Cerro Pachon using the GeMS profiler

Cited by 3 publications

References 10 publications

Towards a reliability assessment of the C²_Nand wind speed vertical profiles retrieved from GeMS

Towards a reliability assessment of the C²_Nand wind speed vertical profiles retrieved from GeMS

Turbulence profiling methods applied to ESO's adaptive optics facility

Atmospheric turbulence profiling with unknown power spectral density

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Statistics of atmospheric turbulence at Cerro Pachon using the GeMS profiler

Cited by 3 publications

References 10 publications

Towards a reliability assessment of the C2Nand wind speed vertical profiles retrieved from GeMS

Towards a reliability assessment of the C2Nand wind speed vertical profiles retrieved from GeMS

Turbulence profiling methods applied to ESO's adaptive optics facility

Atmospheric turbulence profiling with unknown power spectral density

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Product

Resources

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Towards a reliability assessment of the C²_Nand wind speed vertical profiles retrieved from GeMS

Towards a reliability assessment of the C²_Nand wind speed vertical profiles retrieved from GeMS