Coupling CORHEL-CME and PARADISE for Self-Consistent Solar Energetic Particle Modeling: A Proof of Concept with the MLK SEP Event
Dr. Abril Sahade, Goddard Planetary Heliophysics Institute.
Dr. Antonio Niemela, Goddard Planetary Heliophysics Institute.
Coronal mass ejections (CMEs) and their associated shocks are the principal drivers of large gradual solar energetic particle (SEP) events, which pose radiation hazards to crewed missions and technological assets throughout the heliosphere. Physics-based forecasting of these events requires a self-consistent description of both the CME-driven disturbance and the acceleration and transport of the energetic particles it produces. Current SEP transport models are typically driven by simplified, often steady-state or kinematic, descriptions of the CME shock and its connectivity to the ambient solar wind, limiting the fidelity with which particle acceleration and interplanetary transport can be captured.
This project proposes a novel coupling between CORHEL-CME, a coronal and heliospheric MHD modeling suite capable of self-consistently simulating CME evolution from the corona into the heliosphere, and PARADISE, a state-of-the-art test-particle SEP transport model. The coupling will use the time-dependent, three-dimensional MHD fields produced by CORHEL-CME, including the structure and kinematics of the CME-driven shock, as the dynamic background for particle acceleration and transport in PARADISE, replacing the analytic or parameterized backgrounds typically used. This approach extends recent work by our group establishing the coronal and heliospheric evolution of a CME-driven shock, currently under review, whose natural continuation is to model the energetic particles this shock accelerates.
As a proof of concept, we will apply the coupled modeling chain to the SEP event of 18-19 January 2026, which occurred over the Martin Luther King Jr. Day holiday weekend. A long-duration X1.9 flare from active region 4341 launched a full-halo CME with an estimated speed of roughly 1700-2000 km/s. The associated shock remained strong through its transit to 1 AU and, upon arrival about 25 hours later, drove an intense energetic storm particle event: the in-situ greater than 10 MeV proton flux at L1 escalated to S4 (severe) levels, among the highest recorded in decades, and the shock also produced a G5 (Kp = 9-) geomagnetic storm. Unlike several other extreme events previously studied by our group, this CME appears to have propagated without significant preconditioning of the ambient medium by a preceding eruption, and the resulting SEP spectrum was notably soft. This combination of a single, well-characterized shock source and an unambiguous in-situ particle signature at L1 makes it a favorable case for validating the coupled model’s predicted intensity-time profile and spectrum against observations, without the added complexity of interacting eruptions.
The proposed work requires high-resolution three-dimensional MHD simulation of the corona and inner heliosphere together with large ensembles of test-particle transport calculations spanning multiple energy channels, a computational load well beyond desktop resources. Cluster access will allow the resolution- and ensemble-size studies needed to establish the coupling’s robustness before broader application. A successful demonstration will establish a self-consistent CME-to-SEP modeling pipeline directly relevant to NASA’s space weather forecasting effort.