The Elusive Nature of “Seeing”

Tokovinin, Andrei

doi:10.3390/atmos14111694

Cited by 13 publications

(3 citation statements)

References 62 publications

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“…Adaptive optics systems correcting optical distortions in a wide field of view require information about vertical profiles of optical turbulence and wind speed. The key characteristics of the optical turbulence are the structural constant of the air refractive index turbulent fluctuations C 2 n and the atmospheric coherence length, often named the Fried parameter r 0 and seeing [1,2]. These quantities determine the possibilities of reaching a high angular resolution in astronomical observations.…”

Section: Introductionmentioning

confidence: 99%

Optical turbulence vertical distribution at the Peak Terskol Observatory and Mt. Kurapdag

---,

Kopylov,

Potanin

et al. 2024

Preprint

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Atmospheric turbulence characteristics are essential in determining the quality of astronomical images and implementing adaptive optics systems. In this study, the vertical distributions of optical turbulence at the Peak Terskol observatory (43.27472 ° N 42.50083 ° E, 3127 m a.s.l.) using the Era-5 re-analysis and scintillation measurements are investigated. For the closest reanalysis grid node to the observatory, vertical profiles of the structural constant of the air refractive index turbulent fluctuations Cn2 were obtained. The calculated Cn2(z) vertical profiles are compared with the vertical distribution of turbulence intensity obtained from tomographic measurements with Shack-Hartmann sensor. The atmospheric coherence length at the location of Terskol Peak was estimated. Using combination of atmospheric models and scheme paramaterization of turbulence, Cn2(z) profiles at Mt. Kurapdag were obtained. The values of atmospheric coherence length at the Peak Terskol are compared with estimated values of this length at the ten astronomical sites including Ali, Lenghu and Daocheng.

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Section: Introductionmentioning

confidence: 99%

Optical turbulence vertical distribution at the Peak Terskol Observatory and Mt. Kurapdag

---,

Kopylov,

Potanin

et al. 2024

Preprint

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show abstract

“…Adaptive optics systems that correct optical distortions in a wide field of view require information about the vertical profiles of optical turbulence and wind speed. The key characteristics of optical turbulence are the structural constant of the air refractive index turbulent fluctuations (C 2 n ) and the atmospheric coherence length, which are often associated with the Fried parameter (r 0 ) and seeing [1,2]. These quantities determine the potential for achieving high angular resolution in astronomical observations.…”

Section: Introductionmentioning

confidence: 99%

Vertical Distribution of Optical Turbulence at the Peak Terskol Observatory and Mount Kurapdag

Shikhovtsev,

Qing,

Kopylov

et al. 2024

Remote Sensing

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Atmospheric turbulence characteristics are essential in determining the quality of astronomical images and implementing adaptive optics systems. In this study, the vertical distributions of optical turbulence at the Peak Terskol observatory (43.27472°N 42.50083°E, 3127 m a.s.l.) using the Era-5 reanalysis and scintillation measurements are investigated. For the closest reanalysis grid node to the observatory, vertical profiles of the structural constant of the air refractive index turbulent fluctuations Cn2 were obtained. The calculated Cn2(z) vertical profiles are compared with the vertical distribution of turbulence intensity obtained from tomographic measurements with a Shack–Hartmann sensor. The atmospheric coherence length at the location of Terskol Peak was estimated. Using a combination of atmospheric models and paramaterization schemes of turbulence, Cn2(z) profiles at Mt. Kurapdag were obtained. The values of atmospheric coherence length at Peak Terskol are compared with estimated values of this length at the ten astronomical sites, including Ali, Lenghu and Daocheng.

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“…The Earth's atmosphere significantly limits ground-based astronomical observations [1][2][3][4]. Due to atmospheric turbulence, wavefronts distort, solar images are blurred, and small details in the images become indistinguishable.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Astronomical Seeing with Neural Networks at the Maidanak Observatory

Shikhovtsev,

Kiselev,

Kovadlo

et al. 2023

Atmosphere

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In the present article, we study the possibilities of machine learning for the estimation of seeing at the Maidanak Astronomical Observatory (38∘40′24″ N, 66∘53′47″ E) using only Era-5 reanalysis data. Seeing is usually associated with the integral of the turbulence strength Cn2(z) over the height z. Based on the seeing measurements accumulated over 13 years, we created ensemble models of multi-layer neural networks under the machine learning framework, including training and validation. For the first time in the world, we have simulated optical turbulence (seeing variations) during night-time with deep neural networks trained on a 13-year database of astronomical seeing. A set of neural networks for simulations of night-time seeing variations was obtained. For these neural networks, the linear correlation coefficient ranges from 0.48 to 0.68. We show that modeled seeing with neural networks is well-described through meteorological parameters, which include wind-speed components, air temperature, humidity, and turbulent surface stresses. One of the fundamental new results is that the structure of small-scale (optical) turbulence over the Maidanak Astronomical Observatory does not depend or depends negligibly on the large-scale vortex component of atmospheric flows.

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The Elusive Nature of “Seeing”

Cited by 13 publications

References 62 publications

Optical turbulence vertical distribution at the Peak Terskol Observatory and Mt. Kurapdag

Optical turbulence vertical distribution at the Peak Terskol Observatory and Mt. Kurapdag

Vertical Distribution of Optical Turbulence at the Peak Terskol Observatory and Mount Kurapdag

Estimation of Astronomical Seeing with Neural Networks at the Maidanak Observatory

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