Mesoscale Optical Turbulence simulations at Dome C

These last years ground-based astronomy has been looking towards Antarctica, especially its summits and the internal continental plateau where the optical turbulence appears to be confined in a shallow layer close to the icy surface. Preliminary measurements have so far indicated pretty good value for the seeing above 30-35 m: 0.36” (Agabi et al. 2006), 0.27” (Lawrence et al. 2004) and 0.3” (Trinquet et al. 2008) at Dome C. Site testing campaigns are however extremely expensive, instruments provide only local measurements and atmospheric modeling might represent a step ahead towards the search and selection of astronomical sites thanks to the possibility to reconstruct 3D C N maps over a surface of several kilometers. The Antarctic Plateau represents therefore an important benchmark test to evaluate the possibility to discriminate sites on the same plateau. Our group (Hagelin et al. 2008) has proven that the analyses from the ECMWF global model do not describe with the required accuracy the antarctic boundary and surface layers in the plateau. A better description could be obtained with a mesoscale meteorological model. The mesoscale model MesoNh has proven to be reliable in reproducing 3D maps of optical turbulence above midlatitude astronomical sites (Masciadri et al. 1999a,b; Masciadri and Jabouille 2001; Masciadri et al. 2004). In this paper we study the ability of the Meso-Nh model in reconstructing the meteorological parameters as well as the optical turbulence above Dome C with different model configurations (monomodel and grid-nesting). We concentrate our attention on the model abilities in reproducing the optical turbulence surface layer thickness (hsl) and the integral of the C 2 N in the free atmosphere and in the surface layer. It is worth to highlight that these are the first estimates ever done so far with a mesoscale model of the optical turbulence above the internal Antarctic Plateau.