  In the solar corona, magnetic helicity slowly and continuously accumulates in
response to plasma flows tangential to the photosphere and magnetic flux
emergence through it. Analyzing this transfer of magnetic helicity is key for
identifying its role in the dynamics of active regions (ARs). The
connectivity-based helicity flux density method was recently developed for
studying the 2D and 3D transfer of magnetic helicity in ARs. The method takes
into account the 3D nature of magnetic helicity by explicitly using knowledge
of the magnetic field connectivity, which allows it to faithfully track the
photospheric flux of magnetic helicity. Because the magnetic field is not
measured in the solar corona, modeled 3D solutions obtained from force-free
magnetic field extrapolations must be used to derive the magnetic connectivity.
Different extrapolation methods can lead to markedly different 3D magnetic
field connectivities, thus questioning the reliability of the
connectivity-based approach in observational applications. We address these
concerns by applying this method to the isolated and internally complex AR
11158 with different magnetic field extrapolation models. We show that the
connectivity-based calculations are robust to different extrapolation methods,
in particular with regards to identifying regions of opposite magnetic helicity
flux. We conclude that the connectivity-based approach can be reliably used in
observational analyses and is a promising tool for studying the transfer of
magnetic helicity in ARs and relate it to their flaring activity.

Solar and Stellar Astrophysics