Configuration of a Magnetic Cloud From Solar Orbiter and Wind Spacecraft In-situ Measurements

Abstract

Coronal mass ejections (CMEs) represent one type of the major eruption from the Sun. Their interplanetary counterparts, the interplanetary CMEs (ICMEs), are the direct manifestations of these structures when they propagate into the heliosphere and encounter one or more observing spacecraft. The ICMEs generally exhibit a set of distinctive signatures from the in-situ spacecraft measurements. A particular subset of ICMEs, the so-called Magnetic Clouds (MCs), is more uniquely defined and has been studied for decades, based on in-situ magnetic field and plasma measurements. By utilizing the latest multiple spacecraft measurements and analysis tools, we report a detailed study of the internal magnetic field configuration of an MC event observed by both the Solar Orbiter (SO) and Wind spacecraft in the solar wind near the Sun-Earth line. Both two-dimensional (2D) and three-dimensional (3D) models are applied to reveal the flux rope configurations of the MC. Various geometrical as well as physical parameters are derived and found to be similar within error estimates for the two methods. These results quantitatively characterize the coherent MC flux rope structure crossed by the two spacecraft along different paths. The implication for the radial evolution of this MC event is also discussed.

Validation and Interpretation of a Three-dimensional Configuration of a Magnetic Cloud Flux Rope

“…The minimum reduced χ 2 value is 1.44, and the corresponding Q = 0.00687. The set of main parameters as presented in Table 1 represents the optimal output from the fitting procedure with uncertainty estimates based on 90% confidence limits (Press et al 2007;Hu et al 2021b). The parameter C has a magnitude close to 1, indicating significant deviation from a cylindrically symmetric configuration, as we will demonstrate below.…”

“…Such occasions are generally rare and such a validation approach has been carried out for the 2D GS reconstructions of a handful of MC events (Hu et al 2005;Möstl et al 2008Möstl et al , 2009. The latest applications to the quasi-3D model outputs have been performed as well (Hu et al 2021b;Hu 2021). For example, in Hu et al (2021b) an MC structure was observed by both the Solar Orbiter (SO) at a heliocentric distance of ∼0.8 au and the Wind spacecraft at Earth with a longitudinal separation angle of ∼4°.…”

“…The latest applications to the quasi-3D model outputs have been performed as well (Hu et al 2021b;Hu 2021). For example, in Hu et al (2021b) an MC structure was observed by both the Solar Orbiter (SO) at a heliocentric distance of ∼0.8 au and the Wind spacecraft at Earth with a longitudinal separation angle of ∼4°. The analyses of the MC structure with both the 2D GS reconstruction and the quasi-3D model fitting were carried out by using the Wind spacecraft measurements and the expected values of the magnetic field along the SO spacecraft path were produced for both models.…”

Validation and interpretation of three-dimensional configuration of a magnetic cloud flux rope

“…Such occasions are generally rare and such a validation approach has been carried out for the 2D GS reconstructions of a handful of MC events (Hu et al 2005;Möstl et al 2008Möstl et al , 2009. The latest applications to the quasi-3D model outputs were performed as well (Hu 2021;Hu et al 2021b). For example, in Hu et al (2021b), an MC structure was observed by both the Solar Orbiter (SO) at a heliocentric distance ∼0.8 au and Wind spacecraft at Earth with a longitudinal separation angle ∼ 4 • .…”

“…The latest applications to the quasi-3D model outputs were performed as well (Hu 2021;Hu et al 2021b). For example, in Hu et al (2021b), an MC structure was observed by both the Solar Orbiter (SO) at a heliocentric distance ∼0.8 au and Wind spacecraft at Earth with a longitudinal separation angle ∼ 4 • . The analyses of the MC structure with both the 2D GS reconstruction and the quasi-3D model fitting were carried out by using the Wind spacecraft measurements and the expected values of magnetic field along the SO spacecraft path were produced for both models.…”