1 Test Particle Simulations of Solar Energetic Particle Propagation for Space Weather Mike Marsh, S. Dalla, J. Kelly & T. Laitinen University of Central Lancashire

2 COronal Mass Ejections and Solar Energetic Particles: Forecasting the Space Weather Impact 3 yr project funded by the European Union Framework 7 programme (FP7). Aims to provide alerts for SEP radiation storms and geomagnetic storms. Provide a new service for space vulnerable industries, aiding mitigation. Increasing international and European collaboration on space weather research and forecasting.

3 COMESEP The COMESEP Project combines basic research on space weather events with the development of a European space weather alert system. SEP radiation and magnetic storm alerts will be disseminated to the European space weather community. Geomagnetic and SEP radiation storm forecasts based on the automated detection of solar activity and modelling of the evolution of the ICME and energetic particles. The derived SEP and ICME forecast tools will be linked with real-time automated detection of CMEs as they appear when observed at the Sun. Solar Energetic Particles &

4 Solar Energetic Particles (SEPs) = the particles accelerated during flares/CMEs that reach a detecting spacecraft in interplanetary space Many unknowns exist Current SEP Models: Solve kinetic equations – e.g. focussed transport equation. Describe the SEP distribution as a function of distance from the Sun, Assumes that particles move parallel to magnetic field and cannot cross magnetic field lines. However observational data point towards some cross field transport (McKibben et al., 2003; Dalla et al., 2003a,b; Heber et al, 2002; Cane and Erickson, 2003). Test particle approach allows this to be investigated as well as exploration of different IMF configurations. SEP Modelling

5 Test Particle Modelling Plasma is described as a ‘bulk’ fluid with its E and B fields & test particle population. Neglect the fields generated by the test particles. Neglect collisions of test particles with the background plasma. Initial spatial and velocity distributions are specified. Numerically integrate equations of motion. Model is a 3D full-orbit relativistic numerical code. Allows diffusion of particles across the magnetic field to be taken into account

6 Heliospheric Configuration A model used by operations effected by space weather requires computational efficiency. Currently investigating transport in simple Parker interplanetary magnetic field (IMF) for transition from research to operational model. Model has previously been used to study large/small scale turbulence in IMF.

7 Particle Populations Modeled trajectories of a large number of particles. Initial particles injected into model randomly distributed within a specified region 8°×8°. Allows analysis of quantities such as spatial locations, energy spectra etc, over time. Ad-hoc scattering term scatters particles in solar wind frame according to a specified mean free path.

8 Proton Propagation – Example 1 Multiple proton energies 1, 10, 100 MeV. Injected at 0°, 20°, 40° latitude. Scattering mean free path 1 A.U. Note: Co-rotation. Stability of proton stream distributions. Time range ~ 2 days.

9 Proton Propagation – Example 2 Multiple proton energies 1, 10, 100 MeV. Injected at 0° latitude. Scattering mean free path 1 A.U.

10 Proton Propagation – Example 3 Multiple proton energies 1, 10, 100 MeV. Injected at 40° latitude. Scattering mean free path 1 A.U.

11 Next steps… Obtaining observables (time intensity profiles and fluences) from test particle model Introduce CME shock particle injection using Kallenrode, 97 model. Link with other COMESEP tools: CME detection and solar wind models. Optimisation – fast simulation of very large numbers of particles.

12 Thank you. The End…

13 …but, never trust PowerPoint.

14 Proton Propagation – Example 1 Multiple proton energies 1, 10, 100 MeV. Injected at 0°, 20°, 40° latitude. Scattering mean free path 1 A.U. Note: Co-rotation. Stability of proton stream distributions. Time range ~ 2 days.

15 Proton Propagation – Example 2 Multiple proton energies 1, 10, 100 MeV. Injected at 0° latitude. Scattering mean free path 1 A.U.

16 Proton Propagation – Example 3 Multiple proton energies 1, 10, 100 MeV. Injected at 40° latitude. Scattering mean free path 1 A.U.

17 Next steps… Obtaining observables (time intensity profiles and fluences) from test particle model Introduce CME shock particle injection using Kallenrode, 97 model. Link with other COMESEP tools: CME detection and solar wind models. Optimisation – fast simulation of very large numbers of particles.

18 Thank you. THE End.