An Assessment of and Solution to the Intensity Diffusion Error Intrinsic to Short-Characteristic Radiative Transfer Methods
arXiv:1708.09362 · doi:10.3847/1538-4357/aa9178
Abstract
Radiative transfer coupled with highly realistic simulations of the solar atmosphere is routinely used to infer the physical properties underlying solar observations. Due to its computational efficiency, the method of short-characteristics is often employed, despite it introducing numerical diffusion as an interpolation artifact. In this paper, we quantify the effect of the numerical diffusion on the spatial resolution of synthesize emergent intensity images, and derive a closed form analytical model of the diffusion error as a function of viewing angle when using linear interpolation. We demonstrate that the image degradation adversely affects the comparison between simulated data and observations, for observations away from disk-center, unless the simulations are computed at much higher intrinsic resolution than the observations. We also show that the diffusion error is readily avoided by interpolating the simulation solution on a viewing-angle aligned grid prior to computing the radiative transfer. Doing this will be critical for comparisons with observations using the upcoming large aperture telescopes --- the Daniel K. Inouye Solar Telescope and the European Solar Telescope.
Accepted in ApJ on October 3, 2017. 12 pages, 8 figures
References in corpus (6)
- Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
- Non-LTE oxygen line formation in 3D hydrodynamic model stellar atmospheres
- RH 1.5D: a massively parallel code for multi-level radiative transfer with partial frequency redistribution and Zeeman polarisation
- Center-to-Limb Variation of Solar 3-D Hydrodynamical Simulations
- A New Moment Method for Continuum Radiative Transfer in Cosmological Reionization
- Photometric properties of resolved and unresolved magnetic elements