uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Optical turbulence vertical distribution with standard and high resolution at Mt Graham
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
2010 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 404, no 1, 144-158 p.Article in journal (Refereed) Published
Abstract [en]

A characterization of the optical turbulence vertical distribution (C-N(2) profiles) and all the main integrated astroclimatic parameters derived from the C-N(2) and the wind speed profiles above the site of the Large Binocular Telescope (LBT) (Mt Graham, Arizona, USA) is presented. The statistics include measurements related to 43 nights done with a Generalized SCIDAR (GS) used in standard configuration with a vertical resolution Delta H similar to 1 km on the whole 20 km and with the new technique (High Vertical Resolution GS) in the first kilometre. The latter achieves a resolution Delta H similar to 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 C-N(2) . A discretized distribution of C-N(2) , useful for the Ground Layer Adaptive Optics (GLAO) simulations, is provided and a specific analysis for the LBT Laser Guide Star system ARGOS (running in GLAO configuration) case is done including the calculation of the 'grey zones' for J, H and K bands. Mt Graham is confirmed to be an excellent site with median values of the seeing without dome contribution epsilon = 0.72 arcsec, the isoplanatic angle theta(0) = 2.5 arcsec and the wavefront coherence time tau(0) = 4.8 ms. We find that the OT vertical distribution decreases in a much sharper way than what has been believed so far in the proximity of the ground above astronomical sites. We find that 50 per cent of the whole turbulence develops in the first 80 +/- 15 m from the ground. We finally prove that the error in the normalization of the scintillation that has been recently demonstrated in the principle of the GS technique affects these measurements by an absolutely negligible quantity (0.04 arcsec).

Place, publisher, year, edition, pages
2010. Vol. 404, no 1, 144-158 p.
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:uu:diva-132793DOI: 10.1111/j.1365-2966.2010.16313.xISI: 000276794600036OAI: oai:DiVA.org:uu-132793DiVA: diva2:359204
Available from: 2010-10-27 Created: 2010-10-27 Last updated: 2013-01-15Bibliographically approved
In thesis
1. Optical Turbulence Characterization for Ground-Based Astronomy
Open this publication in new window or tab >>Optical Turbulence Characterization for Ground-Based Astronomy
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The optical turbulence, which creates perturbations of the wavefronts coming from the stars, is caused by small-scale fluctuations in the index of refraction of the atmosphere and is a problem for astronomers because it limits the maximum resolution of the ground-based telescopes. One way of identifying the best sites to build astronomical observatories, where the influence of the optical turbulence is as small as possible, is to use the standard meteorological parameters to get a first idea of the potential of a site. In the first part of this thesis the three sites on the Internal Antarctic Plateau that are the most interesting for astronomers (Dome A, Dome C and the South Pole) are investigated using the operational analyses of the ECMWF and a ranking of these three sites is presented.

The second part of this thesis focuses on the ability of the mesoscale model Meso-NH to simulate the optical turbulence as well as the wind speed at Mt Graham (AZ, USA). A rich sample of measurements of the vertical distribution of the optical turbulence, the largest sample used in this type of study so far, is used to calibrate the Meso-NH model and to quantify its ability to simulate the optical turbulence. The measurements are distributed over different periods of the year thus making it possible to evaluate the performance of the model in different seasons. Both the vertical distribution of the optical turbulence and the astroclimatic parameters (seeing, wavefront coherence time and isoplanatic angle) are investigated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 68 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 778
site testing, atmospheric effects, turbulence, optical turbulence, applied meteorology, mesoscale models
National Category
Meteorology and Atmospheric Sciences Astronomy, Astrophysics and Cosmology
Research subject
urn:nbn:se:uu:diva-132798 (URN)978-91-554-7926-8 (ISBN)
Public defence
2010-12-09, Axel Hambergsalen, Geocentrum, Villavägen 16, Uppsala, 10:00 (English)
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 708Available from: 2010-11-17 Created: 2010-10-27 Last updated: 2011-03-21Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Hagelin, Susanna
By organisation
In the same journal
Monthly notices of the Royal Astronomical Society
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 142 hits
ReferencesLink to record
Permanent link

Direct link