Title : SEP Modeling Throughout the Inner Heliosphere Based on the ENLIL Global Heliospheric Model
Abstract : The Community Coordinated Modeling Center (CCMC, http://ccmc.gsfc.nasa.gov) serves as a community access
point to space environment models and as a hub for collaborative development. CCMC is making an effort to make SEP models available for research and operational users soon. We are making steps towards offering a system to run SEP models driven by a variety of heliospheric models. Understanding gradual SEP events well enough to forecast their properties at a given location requires a realistic picture of the global background solar wind through which the shocks and SEPs propagate. The global 3D MHD WSA-ENLIL model provides a time-dependent background heliospheric description, into which a spherical shaped CME can be inserted. Heliospheric models provide contextual information of conditions in the heliosphere, including the background solar wind conditions and shock structures, and are used as input to SEP models, providing an essential tool for understanding SEP properties. ENLIL simulates solar wind parameters and additionally one can extract the magnetic topologies of observer-connected magnetic field lines and all plasma and shock properties along those field lines. Multipoint observations help constrain simulations and the modeling provides global context for observations. ENLIL “likelihood/all-clear” forecasting maps provide expected intensity, timing/duration of events at locations throughout the heliosphere with “possible SEP affected areas” color-coded based on shock strength. ENLIL simulations also drive SEP models such as the Solar Energetic Particle Model (SEPMOD) (Luhmann et al. 2007, 2010) and the Energetic Particle Radiation Environment Module (EPREM) (Schwadron et al., 2010). SEPMOD injects protons onto a sequence of observer field lines at intensities dependent on the connected shock source strength which are then integrated at the observer to approximate the proton flux. EPREM couples with MHD models such as ENLIL and computes energetic particle distributions based on the focused transport equation along a Lagrangian grid of nodes that propagate out with the solar wind. The coupled SEP models allow us to derive the SEP profiles of different types of events throughout the heliosphere. This presentation will demonstrate case studies of SEP event modeling and solar wind simulations at different observers based on WSA-ENLIL+Cone simulations, and compare them with multipoint observations. In addition, an update on the latest model installations at the CCMC and on CCMC-led community-wide model validation projects will be presented.