Magnetic field extrapolation with solar data
Autumn Rolling
Northumbria University
S. Regnier (Northumbria University)
It is well known that the solar corona is dominated by the magnetic field, and that this is a vital component that must be considered in order to understand many of the observed events that occur therein. However, direct measurement of the magnetic field in the corona is not currently feasible. As such, it must be found approximately via extrapolation methods using the photospheric magnetogram data and then compared with observations to assess validity. This means numerically solving a boundary value problem with the available observations and several assumptions used as constraints. Different types of field can arise from this depending on the assumptions made or data used. The simplest of these is the current-free or potential field, which can be used to find the minimum energy state of a magnetic configuration but may not provide a very realistic model where a field is known to be in a more complex state. Other field descriptions, such as the nonlinear force-free field, do take into account the current distribution and therefore may be more applicable to solar data.

The aim of this project is to develop numerical methods that can be used to solve these boundary value problems and then to produce 3D models of the calculated magnetic fields for both test cases and observational data. This could then be used in conjunction with coronal observations to assess qualitatively and quantitatively the merit of the method.