Optical turbulence: site selection above the internal Antarctic plateau with a mesoscale model

Abstract

Atmospherical mesoscale models can offer unique potentialities to characterize and discriminate potential astronomical sites. Our team has recently completely validated the Meso-Nh model above Dome C . Using all the measurements of C 2 N profiles (15 nights) performed so far at Dome C during the winter time (Trinquet et al. 2008) we proved that the model can reconstruct, on rich statistical samples, reliable values of all the three most important parameters characterizing the turbulence features of an antarctic site: the surface layer thickness, the seeing in the free atmosphere and in the surface layer. Using the same Meso-Nh model configuration validated above Dome C, an extended study is now on-going for other sites above the antarctic plateau, more precisely South Pole and Dome A. In this contribution we present the most important results obtained in the model validation process and the results obtained in the comparison between different astronomical sites above the internal plateau. The Meso-Nh model confirms its ability in discriminating between different optical turbulence behaviors, and there is evidence that the three sites have different characteristics regarding the seeing and the surface layer thickness. We highlight that this study provides the first homogeneous estimate, done with comparable statistics, of the optical turbulence developed in the whole 20-22 km above the ground at Dome C, South Pole and Dome A.