Speaker
Description
We investigate how CME-driven shock fronts become quasi-global and enable widespread solar energetic particle (SEP) events. Using EUHFORIA with a GONG–ADAPT coronal background, we simulate the 13 March 2023 eruption by inserting two spheromak CMEs and, crucially, injecting a shock directly at 0.1 au via Rankine–Hugoniot conditions. This design lets the shock evolve without being tethered to the ejecta, exposing the physics of its expanding flanks.
The modeled front rapidly inflates into a ∼global envelope whose flanks propagate and persist like a blast wave, weakening slowly as the fast-magnetosonic speed falls with distance. Forward modeling reproduces multi-point shock arrival times and amplitudes (Parker Solar Probe, Solar Orbiter, STEREO-A, and near-Earth) while showing little evidence for flux-rope crossings at those flank encounters. The result is a quasi-circumsolar shock beyond 2 au—a natural pathway to longitudinally broad SEP/ESP signatures.
Methodologically, direct shock injection in EUHFORIA is the key advance: it captures flank decoupling and globalization that CME-only inner-boundary setups miss, providing a practical route to connect eruptive dynamics with the scope and timing of space-weather impacts.
