On the determination of a moving MHD structure: Minimization of the residue of integrated Faraday's equation

A new method to estimate the spatial structure of the moving magnetohydrodynamic (MHD) system is presented. We integrate the Faraday's induction equation, partial derivative (B) over right arrow/partial derivative t - rot (E) over right arrow, assuming that the system is one-dimensional. The spatial gradient direction, along which the integration is made, is determined by minimizing the residue of the integrated Faraday's equation against the observed magnetic field. This new method can be regarded as an extension of the conventional magnetic minimum variance method. Sample data analyses using this new method for magnetotail events are also presented.