Optical turbulence and outer scales above Dome C in Antarctica

Dome C in Antarctica is a particular astronomical site when considering the optical turbulence conditions. From the first winterover campaign performed in 2005 at Dome C, the set of 34 meteorological balloon profiles has been analyzed. The meteorological balloons were equipped with microthermal sensors used to sense the vertical profile of the optical turbulence intensity C2n. The C2n median profile, mean temperature and mean horizontal wind speed are given. The C2n median profile is characterized by a very strong and thin turbulent surface layer. The surface layer height is defined. The median outer scale profile at Dome C is computed using the Tatarski definition. The von Karman outer scale is also deduced. The integrated parameters as Fried parameter r0, coherence time τ0, isoplanatic angle θ0 and the spatial-coherence outer scale L0 used to define astronomical site quality, are computed at 8 m above the ground and above the turbulent surface layer.