Astronomy & Astrophysics

Free access article

Issue		A&A Volume 422, Number 3, August II 2004
Page(s)		1123 - 1127
Section		Instruments, observational techniques, and data processing
DOI		10.1051/0004-6361:20040215

A&A 422, 1123-1127 (2004)
DOI: 10.1051/0004-6361:20040215

Seeing, outer scale of optical turbulence, and coherence outer scale at different astronomical sites using instruments on meteorological balloons

A. Abahamid¹, J. Vernin², Z. Benkhaldoun¹, A. Jabiri¹, M. Azouit² and A. Agabi²

¹ Laboratoire de Physique des Hautes Énergies et Astrophysique, Département de Physique, Faculté des Sciences Semlalia, BP 2390, Marrakech, Maroc
e-mail: a.abahamid@ucam.ac.ma
² LUAN, UMR 6525, Université de Nice - Sophia Antipolis, 06108 Nice Cedex 2, France

(Received 6 February 2004 / Accepted 24 March 2004)

Abstract
Here we analyze 168 optical turbulence profiles made at nine different locations worldwide by means of free flight balloons equipped with instrumentation. Seeing $\varepsilon_{{\rm FWHM}}$ , optical turbulence outer scales $L_{\rm o}$ , and wavefront outer scales $\pounds_{\rm o}$ are derived for the different locations and taking into account the contribution of the surface layer [0, 50 m], the boundary layer [0, 1 km] and the free atmosphere [1 km, 30 km]. Noticeable changes are found between the different locations, mainly due to the boundary layer contribution as well as the surface layer contribution. The free atmosphere contribution seems almost the same for each site. There is a very good coherence between the outer scale derived by us and that measured using the Generalized Seeing Monitor (GSM) technique.

Key words: turbulence -- atmospheric effects -- balloons

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