Forecasting SEP Atmospheric and Space Radiation by Coupling UMASEP and NAIRAS Models

Abstract The Nowcast of Aerospace Ionizing RAdiation System (NAIRAS) model predicts the radiation environment from the Earth's surface to free‐space. The model output provides dosimetric and particle flux quantities required to assess the hazardous radiation impacts to human health and adverse effects on vehicle electronic systems. The four sources of ionizing radiation included in NAIRAS are galactic cosmic rays (GCR), solar energetic particles (SEP), trapped protons, and trapped electrons. The focus of this paper is to present an advance in the state‐of‐the‐art in SEP radiation modeling by extending the NAIRAS nowcast capability to a forecast capability. A new SEP peak effective dose rate forecast model (for brevity, denoted SEP peak dose forecast) is developed by coupling peak integral proton flux forecast products provided by the University of Málaga Solar particle Event Predictor (UMASEP) model to the input data stream of the NAIRAS model. The UMASEP‐NAIRAS SEP peak dose forecast approach is assessed by analyzing the September 2017 and the May 2024 SEP events. The model forecast uncertainties are characterized at commercial and military aviation altitudes and at low‐Earth orbit (LEO) trajectories similar to the International Space Station (ISS) orbit. The analysis of the two SEP events demonstrates accurate SEP peak dose forecasts bolstering the viability of this forecast approach. The future plan is to make the UMASEP‐NAIRAS SEP peak dose forecast products available in real‐time at the Community Coordinated Modeling Center (CCMC) Integrated Space Weather Analysis Web‐based dissemination system.