Grad-Shafranov reconstruction of Earth's magnetopause with anisotropic pressure

Grad-Shafranov (GS) reconstruction is a technique to analyze the two-dimensional (2-D) coherent field structures of thin current sheets and by using this method one can construct the 2-D predicted values in an optimal co-moving frame from the data measured by a single spacecraft (Hau and Sonnerup, 1999). In this study we have developed and benchmarked a new GS solver based on the modified, extended Grad-Shafranov equations for the ideal magnetohydrodynamic (MHD) model with anisotropic plasma pressure (Hau and Sonnerup, 1993; Hau, 2002; Sonnerup et al., 2006), and applied it to the magnetopause crossing events observed by THEMIS spacecraft. The new GS solver can give rise to the 2-D spatial information of perpendicular and parallel plasma pressures for various thermodynamic conditions described by a set of double polytropic energy laws. We also compare the results based on isotropic and anisotropic GS solvers to examine the effects of pressure anisotropy on the reconstructed 2-D magnetopause structure.