MOSE: operational forecast of the optical turbulence and atmospheric parameters at European Southern Observatory ground-based sites – I. Overview and vertical stratification of atmospheric parameters at 0–20 km

We present an overview of the MOSE (MOdelling ESO Sites) project that aims to prove the feasibility of the forecast of the classical atmospheric parameters (wind-speed intensity and direction, temperature, relative humidity) and the optical turbulence (⁠|CN²| profiles and the most relevant integrated astroclimatic parameters derived from |CN²|⁠; i.e. the seeing ɛ, the isoplanatic angle θ0 and the wavefront coherence time τ0) above the two European Southern Observatory ground-based sites of Cerro Paranal and Cerro Armazones. The final outcome of the study is to investigate the opportunity to implement an automatic system for the forecast of these parameters at these sites. In this paper, we present results related to the meso-nh model ability in reconstructing the vertical stratification of the atmospheric parameters along 20 km above the ground. The very satisfactory performances shown by the model in reconstructing most of these parameters (and, in particular, the wind speed) make this tool of investigation the most suitable to be used in astronomical observatories to support Adaptive Optics facilities and to calculate the temporal evolution of the wind speed and the wavefront coherence time at whatever temporal sampling. A further great advantage of this solution is that such estimates can be available in advance (of the order of some hours) with respect to the time of interest.