Modelling a multi-spacecraft coronal mass ejection encounter with EUHFORIA

Abstract

Context. Coronal mass ejections (CMEs) are a manifestation of the Sun's eruptive nature. They can have a great impact on Earth, but also on human activity in space and on the ground. Therefore, modelling their evolution as they propagate through interplanetary space is essential. Aims. EUropean Heliospheric FORecasting Information Asset (EUHFORIA) is a data-driven, physics-based model, tracing the evolution of CMEs through background solar wind conditions. It employs a spheromak flux rope, which provides it with the advantage of reconstructing the internal magnetic field configuration of CMEs. This is something that is not included in the simpler cone CME model used so far for space weather forecasting. This work aims at assessing the spheromak CME model included in EUHFORIA. Methods. We employed the spheromak CME model to reconstruct a well observed CME and compare model output to in situ observations. We focus on an eruption from 6 January 2013 that was encountered by two radially aligned spacecraft, Venus Express and STEREO-A. We first analysed the observed properties of the source of this CME eruption and we extracted the CME properties as it lifted off from the Sun. Using this information, we set up EUHFORIA runs to model the event.Results. The model predicts arrival times from half to a full day ahead of the in situ observed ones, but within errors established from similar studies. In the modelling domain, the CME appears to be propagating primarily southward, which is in accordance with white-light images of the CME eruption close to the Sun. Conclusions. In order to get the observed magnetic field topology, we aimed at selecting a spheromak rotation angle for which the axis of symmetry of the spheromak is perpendicular to the direction of the polarity inversion line (PIL). The modelled magnetic field profiles, their amplitude, arrival times, and sheath region length are all affected by the choice of radius of the modelled spheromak.

Magnetic Structure and Propagation of Two Interacting CMEs From the Sun to Saturn

“…In-situ measurements of the same CMEs by multiple spacecraft at different radial distances throughout the heliosphere enable studies of their interplanetary evolution (e.g., Burlaga et al, 1981;de Lucas et al, 2011;Good et al, 2018Good et al, , 2019Lugaz et al, 2020;Salman et al, 2020;Vršnak et al, 2019). Additionally, solar and heliospheric remote-sensing observations can be combined with multi-spacecraft in-situ data to obtain a complete picture of the whole solar-heliospheric system when characterizing CME evolution (e.g., Asvestari et al, 2021;Kilpua et al, 2019;Möstl et al, 2015;Nieves-Chinchilla et al, 2012;Palmerio et al, 2021;Prise et al, 2015;J. D. Richardson et al, 2002;Rodriguez et al, 2008;Rouillard et al, 2009).…”

The spheromak tilting and how it affects modelling coronal mass ejections

“…We have addressed the phenomenon of spheromak tilting and drifting in the context of modeling the propagation of spheromak CMEs in the inner heliosphere. Spheromak type flux ropes are frequently used to model magnetised CMEs in MHD simulations of the interplanetary space (see for example Gibson & Low 1998;Vandas et al 2002;Manchester et al 2004aManchester et al ,b, 2014aLugaz et al 2005;Kataoka et al 2009;Singh et al 2018Singh et al , 2020aJin et al 2017;Shiota et al 2016;Verbeke et al 2019;Scolini et al 2020;Asvestari et al 2021). The global magnetic configuration of CMEs is also still an outstanding question, and it is a possibility that some CMEs are spheromaks, or attain a spheromak-like topology via reconnection-driven processes as the eruption evolves from the low to upper corona (Gosling 1990;Vandas et al 1993Vandas et al , 1997Vandas et al , 1998Farrugia et al 1995;Feng et al 2021).…”

“…An introduction to spheromaks and different stationary solutions relevant to lab-implementations can be found in Bellan (2000). Spheromak-type CME implementations in MHD simulation models can be divided in two broad categories, the ones in which the spheromak remains anchored to the inner boundary located in the low corona (see for example, Gibson & Low 1998;Manchester et al 2004aManchester et al ,b, 2014aLugaz et al 2005;Singh et al 2018Singh et al , 2020aJin et al 2017) and those in which it is fully inserted into the middle or upper corona and therefore retains its magnetically confined spherical nature (see for example, Kataoka et al 2009;Shiota et al 2016;Verbeke et al 2019;Scolini et al 2020;Asvestari et al 2021). Note that both of these spheromak types used in the modelling of magnetised CMEs are different from typical lab-implementations of spheromaks: while the latter are stationary, the spheromaks used in CME models are expanding, non-stationary structures.…”

OSPREI: A Coupled Approach to Modeling CME‐Driven Space Weather With Automatically Generated, User‐Friendly Outputs

“…The fluid models include predictions of the density of the CME, but typically the CME is treated as a pressure pulse and does not have an internal magnetic structure. Very sophisticated, fully MHD simulations are possible (e.g., Török et al., 2018; Verbeke et al., 2019), which can provide great details for individual scientific studies (Asvestari et al., 2021; Scolini, Dasso, et al., 2021; Scolini, Winslow, et al., 2021). Some MHD models can be run as ensembles, even those including a magnetic structure for the CME (rather than simply a pressure pulse) but when the models include the coronal evolution of a CME they tend to become difficult to run in real time.…”