Transparent Boundary Conditions for MHD Simulations in Stratified Atmospheres

In this paper we discuss a method of deriving artificial nonreflecting boundary conditions for systems of conservation laws. We focus on an application from solar physics. The governing equations are the equations of ideal compressible magnetohydrodynamics (MHD), which are solved in a gravitationally stratified atmosphere. We derive the necessary equations, discuss implementational aspects, and show the effectiveness and efficiency of our boundary conditions in test calculations.