Elliptical cross-section model for the magnetic topology of magnetic clouds

[1] In this work we present an extension of a previous model for the topology of magnetic clouds which takes into account their interaction with the solar wind. The main consequence of this interaction is the possible distortion of their cross-section, that need no longer be circular during the propagation from the Sun to 1AU. The first approach to this deformation is to assume an elliptical geometry for the cross section although we consider a cylindrical shape for the clouds. Once we make the assumptions of an uniform radial component of the plasma current density and a null value for the radial component of the magnetic field vector, the solutions of the Maxwell equations and the continuity equation in stationary conditions, both expressed in elliptical coordinates, incorporate the expansion of the cross-section of the cloud. To illustrate the model we present the fitting of four selected clouds with different magnetic field profiles. We show in all cases analyzed that the fits are indeed good and have eight free parameters.