Grad-Shafranov Reconstruction of Earth's Magnetopause With Temperature Anisotropy

The Grad-Shafranov (GS) reconstruction may recover the steady two-dimensional magnetohydrodynamic equilibrium structure from single spacecraft data. In this study we report first results on magnetopause structure from a newly developed GS solver that includes the effects of temperature anisotropy and field-aligned flow. Double-polytropic laws are used as energy closure to describe various thermodynamic states for anisotropic plasmas including double-adiabatic and isothermal conditions as special cases. The new GS solver is benchmarked and applied to a Time History of Events and Macroscale Interactions during Substorms magnetopause crossing event with field-aligned flow and p_⊥ > p_∥, where p_⊥ and p_∥ are the pressure components perpendicular and parallel to the local magnetic field, respectively. The recovered magnetic field maps for various thermodynamic conditions show qualitatively similar features with magnetic islands imbedded within the magnetopause current. The mirror-type anisotropy with p_⊥ > p_∥ may lead to relatively inflated magnetic islands as compared to the isotropic case, consistent with earlier theoretical prediction.