Numerical Study of Three‐dimensional Magnetohydrodynamic Instability in the Solar Coronal Magnetic Arcades

Three-dimensional magnetohydrodynamic (MHD) instability in the solar coronal magnetic arcades, which are subject to the constant shearing motion at the feet, was investigated based on the numerical simulations. It was found that the magnetic arcade instability for three-dimensional modes undulating the magnetic arcade can grow if the aspect ratio (defined as the ratio of the arcade length to the width) is larger than unity. In particular, when the aspect ratio is much larger than unity, the nonlinear coupling among several modes dominates the dynamics. As a result, in a very long magnetic arcade, three-dimensional reconnection, which takes place in a limited region in the magnetic arcade, may proceed continuously.