On the Quasi-Three Dimensional Configuration of Magnetic Clouds

Abstract:

Magnetic clouds (MCs) identified in the solar wind from in-situ spacecraft measurements represent a subset of interplanetary coronal mass ejections (ICMEs). They possess a specific set of observational signatures based on magnetic field and plasma parameters. In particular a relatively smooth rotation of the magnetic field and elevated field magnitude usually hint at a well-organized field configuration traversing the single-point observing platform. Additional evidence in support of such a configuration can be obtained from the solar source regions where they originate, generally taken in the form of a flux rope. Based on in-situ spacecraft measurements, various flux rope models in one-dimensional and two-dimensional configurations have been developed and applied to event studies, with the latter represented by the Grad-Shafranov reconstruction technique. However given the significant variability in the in-situ measurements, not all MC events can be modeled successfully by the existing methods. We develop a quasi-three dimensional model which is intrinsically three-dimensional. We demonstrate, in several case studies, that a satisfactory fitting to the in-situ spacecraft data along the path across such a magnetic structure is obtained as judged by the proper Chi^2 statistics, taking into account the underlying data uncertainties.