We performed the first fully data-driven and time-dependent magnetofrictional method (TMFM) simulations of erupting flux ropes in the inner corona using realistic boundary conditions. This approach thus provides self-consistently an estimate of the magnetic structure of the CME flux rope with only magnetograms from the surface of the Sun used as a boundary condition to drive the model. In the later phase of the project the TMFM simulation was coupled with a zero-beta magnetohydrodynamic (MHD) model. We were able to produce with these linked models a stably erupting flux rope which is a big step forward. Our method is computationally efficient, and thus, has the potential to be used in near-real time space weather forecasting. Our latest published results on exploring the optimization of the electric field inversion parameters and contribution to work of developing the automated flux rope extraction tool from the simulation data also support the applicability to space weather forecasting. The project also resulted in a novel scheme to estimate the magnetic structure of flux ropes using a synthesis of several proxies based on remote-sensing solar observations. In particular, our simulation/observational results have been used to constrain magnetized CME flux ropes in our state-of-the-art numerical space weather simulations (e.g. European space weather model EUHFORIA). Our studies using direct solar wind measurements from pairs of lined-up spacecraft revealed that the magnetic field structure of CME flux ropes typically does not significantly change in interplanetary space, but in case of interactions significant deviations can occur even at relatively short heliospheric distances. The outcome of such interaction depends strongly on the magnetic structure of CMEs and our study also highlights the importance of having realistic information of intrinsic CME magnetic fields, accurate modelling of CME propagation in the heliosphere and multi-spacecraft observations.
Our comprehensive analysis showed that certain types of plasma waves (mirror mode and ion acoustic waves) are ubiquitous in CME sheaths, in particular close to the CME-driven shock, and they form at the early stages of CME evolution. Our extensive analyses on magnetic fluctuations and turbulent parameters in CME sheaths have revealed that they are likely combinations of processed fluctuations and new fluctuations generated at shock/sheath processes, but that CME-driven shocks are not resetting the turbulence in a similar manner as planetary bow shocks. The results give information of the properties and locations of the most intense fluctuations and how they relate to driver and upstream properties. The importance of small scale structures and slow CMEs having also prominent sheaths was highlighted by our work. Characterising turbulence and plasma waves in sheaths is also highly important for space weather forecasting. Our project studies have also demonstrated turbulent CME-sheaths perturb particularly strongly the Van Allen radiation belts that circle the Earth. High-energy electrons in the belts are a significant threat to satellites orbiting in that region.
The results have been disseminated to scientific community via publications in the leading journals of the field, active participation of conferences and workshops and via social media (Twitter)
