MOSE: optical turbulence and atmospherical parameters operational forecast at ESO ground-based sites. II: atmospherical parameters in the surface layer [0-30] m

摘要

This article is the second of a series of articles aiming at proving thefeasibility of the forecast of all the most relevant classical atmosphericalparameters for astronomical applications (wind speed and direction,temperature, relative humidity) and the optical turbulence (Cn2 and the derivedastro-climatic parameters like seeing, isoplanatic angle, wavefront coherencetime...). This study is done in the framework of the MOSE project, and focusedabove the two ESO ground-bases sites of Cerro Paranal and Cerro Armazones. Inthis paper we present the results related to the Meso-Nh model ability inreconstructing the surface layer atmospherical parameters (wind speedintensity, wind direction and absolute temperature, [0-30] m a.g.l.). The modelreconstruction of all the atmospherical parameters in the surface layer is verysatisfactory. For the temperature, at all levels, the RMSE (Root Mean SquareError) is inferior to 1{\deg}C. For the wind speed, it is ~2 m/s, and for thewind direction, it is in the range [38-46{\deg}], at all levels, thatcorresponds to a RMSE_relative in a range [21-26{\deg}]. If a filter is appliedfor the wind direction (the winds inferior to 3 m/s are discarded from thecomputations), the wind direction RMSE is in the range [30-41{\deg}], i.e. aRMSE_relative in the range [17-23{\deg}]. The model operational forecast of thesurface layer atmospherical parameters is suitable for different applications,among others: thermalization of the dome using the reconstructed temperature,hours in advance, of the beginning the night; knowing in advance the maindirection which the strong winds will come from during the night could allowthe astronomer to anticipate the occurrence of a good/bad seeing night, andplan the observations accordingly; preventing adaptive secondary mirrors shakegenerated by the wind speed.