3D mapping of optical turbulence using an atmospheric numerical model I. Auseful tool for the ground-based astronomy

These last years have seen the development of many devices to measure and m onitor some atmospheric parameters characterising the image degradation at the telescope focus. Many uncertainties about the possibility to forecast s uch parameters are real although this skill is fundamental for site testing , flexible scheduling and optimization of the performance of both interfero metry and adaptive optics. We present our atmospheric numerical model, conc eived to provide 3D maps of the classic meteorological parameters P, T and V, and also 3D maps of the C-N(2) Optical turbulent profiles. Knowing the w ind V and the C-N(2) profiles, the following integrated parameters are code d: seeing epsilon, coherence wavefront time tau(AO), isoplanatic angle thet a(AO), scintillation rate sigma(I)(2) and spatial coherence outer scale L-o . The ability of the model to produce a 3D map of optical turbulence in the v icinity of a telescope and the effects of horizontal grid size are discusse d. We demonstrate, for the same night, the global coherence of the differen t simulation outputs. Here we consider the use that this model could have i n ground-based astronomy and we describe how it could be used to give a rea l forecast of the optical turbulence.