Modeling of Astroclimatic Parameters by ERA5 at the Roque De Los Muchachos Observatory (ORM) Site

Abstract

Abstract 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. These data have been projected onto the site of the Roque de los Muchachos Observatory (ORM). The analysis covers the main parameters influencing the quality of astronomical observation, notably the vertical profiles of temperature, potential temperature, and optical turbulence ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>C</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> ), as well as the vertical wind distributions and seasonal behaviors of atmospheric turbulence, which are treated in detail by specifying the wind speed at the 200 hPa level ( v 200 ). 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 respectively 0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 48, 0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 72, 2″, and 6 ms. 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. As a preliminary study, this work establishes a scientific basis for further on-site monitoring and detailed characterization of the ORM site.