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

Abstract

Here we analyze 168 optical turbulence profiles made at nine different locations worldwide by means of free flight balloons equipped with instrumentation. Seeing , optical turbulence outer scales Lo, and wavefront outer scales 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.