Analysis of the magnetic field discontinuity at the potential field source surface and Schatten Current Sheet interface in the Wang–Sheeley–Arge model

Abstract

The Wang–Sheeley–Arge solar wind model makes use of coupled potential field source surface (PFSS) and Schatten Current Sheet (SCS) models to reconstruct the coronal magnetic field on the basis of the observed line‐of‐sight photospheric magnetic field and a 1D kinematic code to propagate the solar wind to 1 AU. The source surface serves as the outer boundary of the PFSS model and the inner boundary of the SCS model. Known discontinuities arise in the tangential components of the magnetic field across this surface owing to differences in the imposed boundary conditions (Wang et al., 1998). Here we introduce a more flexible coupling between the two models, which considerably reduces the discontinuous behavior of the magnetic field across the model interface surface, to investigate the effects and importance of these kinks on the accuracy of the model's solar wind speed predictions at 1 AU. A detailed analysis of select Carrington rotations shows that removing the kinks can lead to changes in connectivity, creating different source regions for the solar wind. These changes lead to significantly improved predictions of solar wind structures at 1 AU some of the time, but most of the time, the kinks do not affect the predicted solar wind speed. This improvement is born out statistically by increases in the prediction skill scores of both solar wind velocity (1.7%) and interplanetary magnetic field polarity (1.4%) at 1 AU.