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In addition to astro-meteorological parameters, such as seeing, coherence time and isoplanatic angle, the vertical profile of the Earth's atmospheric turbulence strength and velocity is important for instrument design, performance…

Instrumentation and Methods for Astrophysics · Physics 2018-09-24 James Osborn , Marc Sarazin

An understanding of wind speed and direction as a function of height are critical to the proper modeling of atmospheric turbulence. We have used radiosonde data from launch sites near significant astronomical observatories and created mean…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 Lewis C. Roberts, , L. William Bradford

Canary is the Multi-Object Adaptive Optics (MOAO) pathfinder for the future MOAO-assisted Integral-Field Units (IFU) proposed for Extremely Large Telescopes (ELT). The MOAO concept relies on tomographically reconstructing the turbulence…

Instrumentation and Methods for Astrophysics · Physics 2016-11-23 O. A. Martin , C. M. Correia , E. Gendron , G. Rousset , F. Vidal , T. J. Morris , A. G. Basden , R. M. Myers , Y. H. Ono , B. Neichel , T. Fusco

Recent high-resolution observations have shown stellar winds to harbour complexities which strongly deviate from spherical symmetry, generally assumed as standard wind model. One such morphology is the archimedean spiral, generally believed…

Solar and Stellar Astrophysics · Physics 2015-07-15 Ward Homan , Leen Decin , Alex de Koter , Allard Jan van Marle , Robin Lombaert , Wouter Vlemmings

Next-generation models of wind farm flows are increasingly needed to assist the design, operation, and performance diagnostic of modern wind power plants. Accuracy in the descriptions of the wind farm aerodynamics, including the effects of…

Fluid Dynamics · Physics 2024-06-19 Stefano Letizia , Giacomo Valerio Iungo

This paper presents a machine learning methodology to improve the predictions of traditional RANS turbulence models in channel flows subject to strong variations in their thermophysical properties. The developed formulation contains several…

Fluid Dynamics · Physics 2022-10-28 Rafael Diez Sanhueza , Stephan Smit , Jurriaan Peeters , Rene Pecnik

Knowledge of the Earth's atmospheric optical turbulence is critical for astronomical instrumentation. Not only does it enable performance verification and optimisation of existing systems but it is required for the design of future…

Instrumentation and Methods for Astrophysics · Physics 2018-06-13 J. Osborn , R. W. Wilson , M. Sarazin , T. Butterley , A. Chacón , F. Derie , O. J. D. Farley , X. Haubois , D. Laidlaw , M. LeLouarn , E. Masciadri , J. Milli , J. Navarrete , M. J. Townson

An adaptive optics system with a single deformable mirror is being implemented on the THEMIS 90cm solar telescope. This system is designed to operate in the visible and is required to be as robust as possible in order to deliver the best…

Instrumentation and Methods for Astrophysics · Physics 2021-01-11 Michel Tallon , Éric Thiébaut , Maud Langlois , Bernard Gelly , Richard Douet , Clémentine Béchet , Loïc Denis , Gil Moretto

We use telemetry data from the Gemini North ALTAIR adaptive optics system to investigate how well the commands for wavefront correction (both Tip/Tilt and high-order turbulence) can be forecasted in order to reduce lag error (due to…

Instrumentation and Methods for Astrophysics · Physics 2022-05-16 Rehan Hafeez , Finn Archinuk , Sébastien Fabbro , Hossen Teimoorinia , Jean-Pierre Véran

We present the development, tests and first results of the second generation Low Layer Scidar (LOLAS-2). This instrument constitutes a strongly improved version of the prototype Low Layer Scidar, which is aimed at the measurement of optical…

Instrumentation and Methods for Astrophysics · Physics 2016-06-17 R. Avila , C. A. Zuniga , J. J. Tapia-Rodriguez , L. J. Sanchez , I. Cruz-Gonzalez , J. L. Aviles , O. Valdes-Hernandez , E. Carrasco

We present results from the first year of a campaign to characterize and monitor the optical turbulence profile at the SAAO Sutherland observing station in South Africa. A MASS-DIMM (MultiAperture Scintillation Sensor - Differential Image…

Instrumentation and Methods for Astrophysics · Physics 2013-10-29 Laure Catala , Steven M. Crawford , David A. H. Buckley , Tim Pickering , Richard Wilson , Tim Butterley , Harry Shepherd , Fred Marang , Patrick Matshaya , Chantal Fourie

We have developed a new software to perform the measurement of galaxy cluster pressure profiles from high angular resolution thermal SZ observations. The code allows the user to take into account various features of millimeter observations,…

Solar flares create adverse space weather impacting space and Earth-based technologies. However, the difficulty of forecasting flares, and by extension severe space weather, is accentuated by the lack of any unique flare trigger or a single…

Solar flares are among the most severe space weather phenomena, and they have the capacity to generate radiation storms and radio disruptions on Earth. The accurate prediction of solar flare events remains a significant challenge, requiring…

Solar and Stellar Astrophysics · Physics 2023-10-31 Vysakh P. A. , Prateek Mayank

We propose a dimensionality reduction and unsupervised clustering method for the automatic classification and reduced-order modeling of density-stratified turbulence in laboratory experiments. We apply this method to 113 long shadowgraph…

Fluid Dynamics · Physics 2023-05-09 Adrien Lefauve , Miles M. P. Couchman

Detailed knowledge of the mesopheric sodium layer characteristics is crucial to estimate and optimize the performance of Laser Guide Star (LGS) assisted Adaptive Optics (AO) systems. In this paper, we present an analysis of two sets of data…

Instrumentation and Methods for Astrophysics · Physics 2013-01-17 Benoit Neichel , Celine D'Orgeville , Joseph Callingham , Francois Rigaut , Claudia Winge , Gelys Trancho

Two-wavelength adaptive optics (AO) systems sense turbulence-induced wavefront distortions using an artificial beacon or natural guidestar at one wavelength, while correcting and possibly transmitting at another. Although most existing AO…

Optics · Physics 2025-05-02 Milo W. Hyde , Matthew Kalensky , Mark F. Spencer

We propose a short-term wind forecasting framework for predicting real-time variations in atmospheric turbulence based on nacelle-mounted anemometer and ground-level air-pressure measurements. Our approach combines linear stochastic…

Fluid Dynamics · Physics 2024-12-20 Seyedalireza Abootorabi , Stefano Leonardi , Mario Rotea , Armin Zare

We attempt to forecast M-and X-class solar flares using a machine-learning algorithm, called Support Vector Machine (SVM), and four years of data from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager, the first instrument…

Solar and Stellar Astrophysics · Physics 2015-01-09 Monica G. Bobra , Sebastien Couvidat

Atmospheric turbulence degrades the performance of free-space optical (FSO) communication and remote sensing systems by introducing phase and intensity distortions. While a majority of research focuses on mitigating these effects to ensure…