Modeling of astroclimatic parameters by ERA5 at the Roque de los Muchachos Observatory (ORM) site

In this article, we have modeled the astroclimatic parameters using data from the fifth reanalysis series (ERA5) from the European Centre for Medium-Range Weather Forecasts over the period 2010–2020. This data has been projected onto the site of the Roque de Los Muchachos Observatory (ORM). L'analyse couvre les principaux paramètres influençant la qualité de l'observation astronomique, notamment les profils verticaux de température, de température potentielle, de turbulence optique (Cₙ²), ainsi que les distributions verticales du vent et les comportements saisonniers de la turbulence atmosphérique, qui sont traités en détail en spécifiant la vitesse du vent au niveau de 200 hPa (v₂₀₀). Around this level, the wind at high altitude presents moderate speeds and a generally stable direction, conditions favorable for adaptive optics. The thermal profiles show good agreement with standard atmospheric models, with a well-defined tropopause and a stable stratosphere. as well as the integrated parameters such as seeing (free and total), isoplanatic angle, and coherence time. The results reveal a stratified and stable atmosphere, with turbulence predominantly concentrated in the lower troposphere. The thermal profiles show a good agreement with standard atmospheric models, with a well-defined tropopause and a stable stratosphere. The seasonality of the astroclimatic parameters indicates conditions particularly favorable for observation during the winter months, with the median of free seeing, total seeing, isoplanatic angle and a coherence time as respectivly 0.48 arcsec, 0.72 arcsec, 2 arcsec, and 6 cm. These results confirm the strong potential of ORM as a reference astronomical site, capable of hosting high-precision observation instruments. The methodological approach employed also provides a replicable basis for the characterization of other candidate sites for the installation of ground-based telescopes.