Original title: On the Effect of Large Scale Structures and Turbulence on Solar Eruptive Events: The Cross-Scale Challenge for Space Weather
Alessandro Ippolito, Giuseppe Prete, Nicolas Wijsen, Gaetano Zimbardo +3 · August 2026
Giant solar eruptions called Coronal Mass Ejections, or CMEs, drive space weather, but they are hard to predict. Big computer models track the CME's massive shape, but they miss tiny turbulent fluctuations. These small swirls dictate how magnetic fields connect and how fast-moving particles travel through space. To solve this, researchers built MICMAC. This model blends large-scale simulations from EUHFORIA with small-scale random-walk simulations of turbulence. They tracked magnetic field lines and 100 MeV protons from a CME shock out to 1 AU, near Earth. They found that turbulence widens, twists, and breaks up the magnetic connection to Earth into patchy, uneven patterns. This unevenness increases as the eruption nears Earth, showing unusual diffusion. Ultimately, models must combine massive solar structures with tiny turbulence to accurately forecast space weather.
Imagine trying to mail a letter through a city where the streets constantly shift. You know the general direction of the destination, but every time you choose a route, the streets rearrange. The letter ends up in a completely different neighborhood than expected. In this paper, the CME is like the letter, and the Sun's turbulent magnetic field is like the shifting streets. The researchers show that the turbulence spreads out where the letter arrives, making it hard to predict.
Space weather forecasters currently ignore small-scale turbulence when predicting when solar particles will hit Earth. This work shows that turbulence dramatically spreads out and distorts the magnetic connection, making arrival times and intensities much harder to predict. To protect satellites and astronauts, future models must include this cross-scale effect.
The abstract describes only one extreme CME event and uses a simplified shear-layer toy model. It does not validate the model against actual observations or discuss computational cost. The general applicability to other CMEs and the scalability of the MICMAC approach are not addressed.
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On the Effect of Large Scale Structures and Turbulence on Solar Eruptive Events: The Cross-Scale Challenge for Space Weather — Alessandro Ippolito, Giuseppe Prete, Nicolas Wijsen et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.