Mt. Graham: optical turbulence vertical distribution with standard and high resolution

Elena Masciadri; Jeff Stoesz; Susanna Hagelin; Franck Lascaux

doi:10.1117/12.856904

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6 August 2010 Mt. Graham: optical turbulence vertical distribution with standard and high resolution

Elena Masciadri, Jeff Stoesz, Susanna Hagelin, Franck Lascaux

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Proceedings Volume 7733, Ground-based and Airborne Telescopes III; 77331P (2010) https://doi.org/10.1117/12.856904
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

Abstract

A characterization of the optical turbulence vertical distribution and all the main integrated astroclimatic parameters derived from the C²_N and the wind speed profiles above Mt. Graham is presented. The statistic includes measurements related to 43 nights done with a Generalized Scidar (GS) used in standard configuration with a vertical resolution of ~1 km on the whole 20-22 km and with the new technique (HVR-GS) in the first kilometer. The latter achieves a resolution of ~ 20-30 m in this region of the atmosphere. Measurements done in different periods of the year permit us to provide a seasonal variation analysis of the C²_N. A discretized distribution of the typical C²_N profiles useful for the Ground Layer Adaptive Optics (GLAO) simulations is provided and a specific analysis for the LBT Laser Guide Star system ARGOS case is done including the calculation of the 'gray zones' for J, H and K bands. Mt. Graham confirms to be an excellent site with median values of the seeing without dome contribution equal to 0.72", the isoplanatic angle equal to 2.5" and the wavefront coherence time equal to 4.8 msec. We provide a cumulative distribution of the percentage of turbulence developed below H* where H* is included in the (0,1 km) range. We find that 50% of the whole turbulence develops in the first 80 m from the ground. The turbulence decreasing rate is very similar to what has been observed above Mauna Kea.

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Elena Masciadri, Jeff Stoesz, Susanna Hagelin, and Franck Lascaux "Mt. Graham: optical turbulence vertical distribution with standard and high resolution", Proc. SPIE 7733, Ground-based and Airborne Telescopes III, 77331P (6 August 2010); https://doi.org/10.1117/12.856904

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