On the quasi-three dimensional configuration of magnetic clouds

TL;DR

This paper introduces an optimization method to model the complex three-dimensional magnetic field configurations of magnetic clouds, revealing their helical and double-helix structures through case studies with real in-situ data.

Contribution

It develops a new linear-force free modeling approach with helical symmetry, extending previous models and demonstrating its effectiveness on actual magnetic cloud data.

Findings

Reduced chi-squared close to 1 in case studies

Identification of helical and double-helix magnetic structures

Demonstration of 3D complexity in magnetic clouds

Abstract

We develop an optimization approach to model the magnetic field configuration of magnetic clouds, based on a linear-force free formulation in three dimensions. Such a solution, dubbed the Freidberg solution, is kin to the axi-symmetric Lundquist solution, but with more general "helical symmetry". The merit of our approach is demonstrated via its application to two case studies of in-situ measured magnetic clouds. Both yield results of reduced $\chi^2\approx 1$. Case 1 shows a winding flux rope configuration with one major polarity. Case 2 exhibits a double-helix configuration with two flux bundles winding around each other and rooted on regions of mixed polarities. This study demonstrates the three-dimensional complexity of the magnetic cloud structures.