| dc.description.abstract | Accurate determination of the properties of the solar atmosphere is very important for the understanding of the physical mechanisms of solar activities. However, the properties of the solar atmosphere cannot be directly measured by current observational techniques, and have to be inferred from the directly detected electromagnetic waves, specifically, polarized light. The technique to infer the properties of the medium from the observed polarized spectra (Stokes parameters) is called Spectropolarimetry.
The main objective of this research is to examine the relationships between the variations of the properties of the medium and the variations of the profiles of the Stokes parameters by a numerical simulation method. The results can provide a guideline on how to adjust the solar atmosphere models to be more consistent with the real Sun.
In this research, we use the sunspot model by Rempel(2012) and choose 6302.5Å absorption line for our study. The Stokes parameters profiles the absorption line in the umbra, penumbra and quiet Sun regions of are computed by solving the Radiative Transfer Equation (RTE) using the trapezoidal method. Different physical parameters (magnetic field, temperature, number density and line-of-sight velocity) are perturbed at different depths, and their effects on the profiles of different Stokes parameters are investigated.
The results indicate that Stokes parameters are mainly affected by the perturbation in the depth 〖log〗_10〖τ_c 〗=-1~1. The temperature causes the largest variation in all four Stokes parameters in all studied regions. The relative importance of other physical quantites is different in different regions for different Stokes parameters at different wavelength. The results can help solar modelers to adjust their models to reduce the difference between the model-predicted and observed Stokes parameters.
In addition, to reduce computation time, we examine the consistency between the numerical solution of RTE and an analytical solution derived under the assumption of small perturbation. The results indicate that the analytical solution, which can be computed much faster, is consistent with the numerical solution if the spectral resolution is sufficiently high. | en_US |