A data assimilation-based forecast model of outer radiation belt electron fluxes

Because radiation belt electrons can pose a potential threat to the safety of satellites orbiting in space, it is of great importance to develop a reliable model that can predict the highly dynamic variations in outer radiation belt electron fluxes. In the present study, we develop a forecast model of radiation belt electron fluxes based on the data assimilation method, in terms of Van Allen Probe measurements combined with three-dimensional radiation belt numerical simulations. Our forecast model can cover the entire outer radiation belt with a high temporal resolution (1 hour) and a spatial resolution of 0.25 L over a wide range of both electron energy (0.1–5.0 MeV) and pitch angle (5°–90°). On the basis of this model, we forecast hourly electron fluxes for the next 1, 2, and 3 days during an intense geomagnetic storm and evaluate the corresponding prediction performance. Our model can reasonably predict the storm-time evolution of radiation belt electrons with high prediction efficiency (up to ~0.8–1). The best prediction performance is found for ~0.3–3 MeV electrons at L = ~3.25–4.5, which extends to higher L and lower energies with increasing pitch angle. Our results demonstrate that the forecast model developed can be a powerful tool to predict the spatiotemporal changes in outer radiation belt electron fluxes, and the model has both scientific significance and practical implications.