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

Abstract

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.

Optical turbulence forecast over short timescales using machine learning techniques

“…Milli's paper also make use of wind speed measurements at 200mb (jet stream level), however such measurements are not available in ESO database and are technically complex to obtain, so the impact of 200mb wind is evaluated separately. To do so we selected a limited data period from 2018-08-01 to 2019-08-01, with the training set from 2018-08-01 to 2019-02-01 (0.5 years) and Test set from 2019-02-01 to 2019-08-01 (0.5 years), where we managed to obtain 200mb wind speed data from simulations done with a mesoscale model, since this solution has already proven able to reconstruct the vertical profile of the wind with extreme precision [12,13]. In Fig.…”

Characterizing turbulence profile layers through celestial single-source observations

“…It has recently been shown that AO controllers primed with turbulence and wind velocity profile information can significantly improve the observed Strehl ratio during satellite downlink [10]. Additionally, turbulence and wind velocity profile information assists the development, calibration and validation of forecasts [11][12][13]. Atmospheric profiling is therefore greatly important to both astronomy and ground-space FSOC.…”

Site-testing at Muztagh-ata site III: temperature inversion in surface-layer atmosphere

“…As important characteristic for optical observatories, temperature and wind speed gradients result in the formation of optical turbulence, while the spatial and temporal stability of these quantities in turn determine the performance of Adaptive Optics (AO) systems . When it comes to the temperature and wind speed profiles through the atmosphere, weather balloons ) and the SLODAR technique (Sivo et al 2018) are usually employed for acquiring temperature and wind speed values higher than 100 m. Near-surface wind and temperature structures usually play a pivotal role in determining the momentum and energy exchange between the Earth's surface and the atmosphere (Zhou et al 2009). Aristidi et al (2009) found that the median value of the boundary layer height at Antarctic Dome C is 33 m. Bonner et al (2010) reported a median boundary layer height of 13.9 m for Antarctic Dome A.…”