Assessment of and a Solution to the Intensity Diffusion Error Intrinsic in Short-Characteristic Radiative Transfer
Abstract
Short characteristic radiative transfer coupled with 3D MHD simulations are routinely used to compare simulations with observations of the solar atmosphere. While it has been known that the method of short characteristics radiative transfer results in intensity diffusion, it has been routinely employed to solve radiative transfer due to its computational expediency. In this talk, we discuss the effect of spatial smearing due to short characteristics radiative transfer under both linear and high-order interpolation. We then demonstrate that linear interpolation results in an effective spatial smearing related to the number of grid heights above the τ = 1 surface and conserves intensity. Additionally, we show that the use of high-order strict monotonic interpolation reduces the amount of smearing, but at the expense of error in the integrated emergent intensity. Finally, we demonstrate that these issues can be easily avoided at no added computational expense by interpolating the atmosphere onto a ray-directed grid and computing the radiative transfer for vertical rays through the grid.
- Publication:
-
AAS/Solar Physics Division Abstracts #48
- Pub Date:
- August 2017
- Bibcode:
- 2017SPD....4820701P