Flare Energetics, CME Launch and Heliospheric Propagation for the May 2024 Events, as Derived from Ensemble MHD Modelling

By: Brigitte Schmieder, Jinhan Guo, Guillaume Aulanier, Anwesha Maharana & Stefaan Poedts

Understanding how magnetic flux emerging through the solar surface triggers major space weather events remains a key challenge. This study investigates the physical connection between solar magnetic activity, flare energetics, and coronal mass ejections (CMEs) during the intense events of May 2024. Using three complementary magnetohydrodynamic (MHD) models—OHM, TMF combined with zero-β MHD, and EUHFORIA—the team quantified the buildup of free magnetic energy and helicity in active regions and followed CME propagation from the Sun to Earth. The simulations revealed that magnetic energy accumulation of approximately 5.2 × 10³² erg preceded the observed eruptions, and that EUHFORIA successfully predicted CME arrival times at Earth within 3 hours. The results confirm that integrating data-driven and idealised MHD models provides a powerful approach to understanding flare–CME coupling and improving space weather forecasting capabilities.

Figure 1: Evolution of the field lines during the eruption. The yellow lines represent the eruption of the flux rope, and the pink lines represent the current sheet below the flux rope.

Key Findings

• Energy Build-Up and Flare Prediction Using MHD simulations (OHM and TMF), the study shows that magnetic energy and helicity build-up in active regions (ARs) are reliable indicators of potential flare activity. For the May 2024 events, the estimated magnetic free energy reached about 5.2 × 10³² erg, consistent across both idealised and data-driven models.

• CME Initiation and Propagation The simulations confirm that twisted flux ropes formed along polarity inversion lines are precursors to CMEs. The EUHFORIA model successfully predicted CME arrival times at Earth with an accuracy of less than 3 hours, though speed profiles varied depending on input magnetograms.

• Model Comparisons and Limitations The OHM model provides upper-limit energy estimates but oversimplifies complex ARs. The TMF + zero-β MHD approach offers a more realistic evolution but is computationally intensive.

• Space Weather Forecasting Potential The study emphasises the importance of integrating multiple models—from the solar surface to the heliosphere—for reliable space weather forecasting. Future improvements include incorporating magnetic CME models and AI-based magnetogram prediction.

Figure 2: The speed and number density profile of the best predicted EUHFORIA simulation (default VSWMC setup) plotted with the in situ data obtained by the WIND spacecraft for Run 1 (top) using the magnetogram of May 5 2024 and Run 2 (bottom) using the magnetogram of May 8 2024. The light and dark shades around the EUHFORIA profile represent predictions at virtual satellites placed and away from Earth, providing some error bars on the direction of the CMEs. We still note a more accurate arrival time definition with Run 1.

How did VSC contribute to the research?

The VSC (Flemish Supercomputer Centre) was used in this study to perform the computationally intensive magnetohydrodynamic (MHD) simulations that underpin the analysis of solar flare energetics, CME initiation, and heliospheric propagation.

Specifically, the VSC infrastructure enabled:

• Data-driven simulations of active region magnetic field evolution using the TMF and zero-β MHD models.

• EUHFORIA simulations for CME propagation from the Sun to Earth.

• Handling of large datasets and high-resolution magnetograms with fine spatial and temporal grids (e.g., 1.5 million cells and 5-minute time steps).

VSC was acknowledged as essential for achieving the computational performance required for realistic and timely space weather modelling.

Space Weather Forecasting at Its Finest!

Professor Stefaan Poedts, a long-time VSC user, continues to push the boundaries of plasma astrophysics using our supercomputing facilities. His research on coronal mass ejections (CMEs) is crucial for understanding and predicting solar storms that can affect Earth’s technology and infrastructure.

We’re proud that VSC’s HPC expertise supports his computational modeling, helping refine predictions and ensure timely warnings. In recognition of his leadership in space weather research, Prof. Poedts received his fourth consecutive ERC grant in 2024 for Open SESAME, advancing solar atmosphere modeling and forecasting capabilities.

Read the full publication in Springer Nature here

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