AO4ELT5 Proceedings

Nowcasting of the surface layer of turbulence at Paranal Observatory

Butterley, Timothy (Durham University), Osborn, James (Durham University), Sarazin, Marc (ESO), Wilson, Richard (Durham University)

The surface layer of turbulence at Paranal Observatory is monitored by an automated surface layer Slope Detection and Ranging (SLODAR) profiler. This has two main purposes. Firstly, the high resolution surface layer profile it provides allows the fraction of turbulence that is below the level of the Unit Telescope (UT) mirrors to be estimated, and thus a total seeing estimate for the UTs to be made. Secondly, it can measure up to the minimum altitude at which the MASS is sensitive, so together they provide a profile of the full atmosphere. This allows performance of the Adaptive Optics Facility (AOF) to be predicted before committing the instrument to an observation. The SLODAR instrument has been operating at Paranal since August 2013. We present an overview of the SLODAR data collected to date and concurrent meteorological measurements made on-site, and place bounds on the accuracy with which the surface layer turbulence can be “nowcasted” based on live local weather data. This could be an invaluable tool in scheduling adaptive optics observations.

DOI: 10.26698/AO4ELT5.0153- Proceeding PDF

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