Effect of Numerical Resolution on Synthetic Observables of Simulated Coronal Loops

TL;DR

This study investigates how the spatial resolution of 3D radiative MHD simulations of coronal loops influences synthetic observables, revealing that resolutions finer than 24 km offer limited additional benefits for modeling bulk properties.

Contribution

It quantifies the impact of numerical resolution on simulated coronal loop properties and synthetic observables, providing guidelines for optimal resolution choices.

Findings

Higher resolution increases atmospheric complexity and dynamics.

Resolution affects emission intensity and velocity distributions.

Resolution beyond 24 km offers limited improvements.

Abstract

Increasingly realistic simulations of the corona are used to predict synthetic observables for instruments onboard both existing and upcoming heliophysics space missions. Synthetic observables play an important role in constraining coronal heating theories. Choosing the spatial resolution of numerical simulations involves a trade-off between accuracy and computational cost. Since the numerical resolution not only affects the scale of structures that can be resolved, but also thermodynamic quantities such as the average coronal density, it is important to quantify the effect on synthesized observables. Using 3D radiative MHD simulations of coronal loops at three different grid spacings, from 60 km down to 12 km, we find that changes in numerical resolution lead to differences in thermodynamic quantities and stratification as well as dynamic behaviour. Higher grid resolution results in a more complex and dynamic atmosphere. The resolution affects the emission intensity as well as the velocity distribution, thereby affecting synthetic spectra derived from the simulation. The distribution of synthetic coronal loop strand sizes changes as more fine-scale structure is resolved. A number of parameters, however, seem to start to saturate from our chosen medium grid resolution on. Our study shows that while choosing a sufficiently high resolution matters when comparing forward-modelled observables with data from current and future space missions, for most purposes not much is gained by further increasing the resolution beyond a grid spacing of 24 km, which seems to be adequate for reproducing bulk loop properties and forward-modelled emission, representing a good trade-off between accuracy and computational resource.