Wind speed vertical distribution at Mt Graham

Hagelin, Susanna; Masciadri, E.; Lascaux, F.

doi:10.1111/j.1365-2966.2010.17102.x

Cited by 24 publications

(16 citation statements)

References 19 publications

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“…General circulation models (GCM), such as GFS, have been previously used to provide free atmosphere (above the ground layer) wind velocity profiles (for example, Hagelin et al 2010, and references therein). It is known that these models can be unreliable in the lower atmosphere, where local geography can influence the climatic parameters.…”

Section: Gfsmentioning

confidence: 99%

Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

Osborn¹,

Butterley²,

Townson³

et al. 2016

Mon. Not. R. Astron. Soc.

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As telescopes become larger, into the era of ∼40 m Extremely Large Telescopes, the high resolution vertical profile of the optical turbulence strength is critical for the validation, optimisation and operation of optical systems. The velocity of atmospheric optical turbulence is an important parameter for several applications including astronomical adaptive optics systems. Here, we compare the vertical profile of the velocity of the atmospheric wind above La Palma by means of a comparison of Stereo-SCIDAR with the Global Forecast System models and nearby balloon borne radiosondes. We use these data to validate the automated optical turbulence velocity identification from the Stereo-SCIDAR instrument mounted on the 2.5 m Isaac Newton Telescope, La Palma. By comparing these data we infer that the turbulence velocity and the wind velocity are consistent and that the automated turbulence velocity identification of the Stereo-SCIDAR is precise. The turbulence velocities can be used to increase the sensitivity of the turbulence strength profiles, as weaker turbulence that may be misinterpreted as noise can be detected with a velocity vector. The turbulence velocities can also be used to increase the altitude resolution of a detected layer, as the altitude of the velocity vectors can be identified to a greater precision than the native resolution of the system. We also show examples of complex velocity structure within a turbulent layer caused by wind shear at the interface of atmospheric zones.

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Section: Gfsmentioning

confidence: 99%

Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

Osborn¹,

Butterley²,

Townson³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…General circulation models (GCM) have been used to provide wind velocity profiles for previous astronomical studies (for example, Hagelin et al 2010;Osborn et al 2017). They have also been used as the input for mesoscale turbulence forecast models (for example, Giordano et al 2013;Masciadri et al 2017).…”

Section: General Circulation Modelsmentioning

confidence: 99%

Atmospheric turbulence forecasting with a general circulation model for Cerro Paranal

Osborn

Sarazin

2018

Monthly Notices of the Royal Astronomical Society

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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 validation and monitoring, and observation scheduling and management. Here we compare these astro-meteorological parameters as well as the vertical profile itself from a forecast model based on a General Circulation Model from the European Centre for Median range Weather Forecasts and the stereo-SCIDAR, a highsensitivity turbulence profiling instrument in regular operation at Paranal, Chile. The model is fast to process as no spatial nesting or data manipulation is performed. This speed enables the model to be reactive based on the most up to date forecasts. We find that the model is statistically consistent with measurements from stereo-SCIDAR. The correlation of the median turbulence profile from the model and the measurement is 0.98. We also find that the distributions of astro-meteorological parameters are consistent. We compare contemporaneous measurements and show that the free atmosphere seeing, isoplanatic angle and coherence time have correlation values of 0.64, 0.40 and 0.63 respectively. We show and compare the profile sequences from a large number of trial nights. We see that the model is able to forecast the evolution of dominating features. In addition to smart scheduling, ensuring that the most sensitive astronomical observations are scheduled for the optimum time, this model could enable remote site characterisation using a large archive of weather forecasts and could be used to optimise the performance of wide-field AO system.

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“…Indeed, if we look at the climatology of the C 2 N , at latitudes typical of astronomical observatories, we observe that the optical turbulence is very weak above 20 km (for example Garcia-Lorenzo & Fuensalida (2011), Garcia-Lorenzo & Fuensalida (2011b)). If we look at the climatology of the WS, we observe that the wind speed reaches a maximum at 11-13 km and then it decreases inexorably at heights of the order of 20 km or more (see for example Hagelin et al (2010)). This is therefore a reasonable spatial scale.…”

Section: Modelmentioning

confidence: 99%

Towards an automatic wind speed and direction profiler for Wide Field adaptive optics systems

Sivo

Turchi

Masciadri

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Wide Field Adaptive Optics (WFAO) systems are among the most sophisticated AO systems available today on large telescopes. The knowledge of the vertical spatiotemporal distribution of the wind speed (WS) and direction (WD) are fundamental to optimize the performance of such systems. Previous studies already proved that the Gemini Multi-Conjugated AO system (GeMS) is able to retrieve measurements of the WS and WD stratification using the SLODAR technique and to store measurements in the telemetry data. In order to assess the reliability of these estimates and of the SLODAR technique applied to such a kind of complex AO systems, in this study we compared WS and WD retrieved from GeMS with those obtained with the atmospherical model Meso-Nh on a rich statistical sample of nights. It has been previously proved that, the latter technique, provided an excellent agreement with a large sample of radiosoundings both, in statistical terms and on individual flights. It can be considered, therefore, as an independent reference. The excellent agreement between GeMS measurements and the model that we find in this study, proves the robustness of the SLODAR approach. To by-pass the complex procedures necessary to achieve automatic measurements of the wind with GeMS, we propose a simple automatic method to monitor nightly WS and WD using the Meso-Nh model estimates. Such a method can be applied to whatever present or new generation facilities supported by WFAO systems. The interest of this study is, therefore, well beyond the optimization of GeMS performance.

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Wind speed vertical distribution at Mt Graham

Cited by 24 publications

References 19 publications

Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

Turbulence velocity profiling for high sensitivity and vertical-resolution atmospheric characterization with Stereo-SCIDAR

Atmospheric turbulence forecasting with a general circulation model for Cerro Paranal

Towards an automatic wind speed and direction profiler for Wide Field adaptive optics systems

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