1. Storm-dependent Radiation Belt Dynamics Mei-Ching Fok NASA Goddard Space Flight Center, USA Richard Horne, Nigel Meredith, Sarah Glauert British Antarctic Survey, UK AOGS 5th Annual General Meeting 16-20 June 2008 Busan, Korea ST03-A008

2. Motivation Taken from Reeves et al., 2003

3. Outline  Model the radiation belt enhancements during the storms in October 2002  Two-step acceleration processes –– What causes post-storm enhancement in the outer belt?  Real-time running of the RBE model at NASA Goddard  The Radiation Belt Environment (RBE) model  Model logic  Model formulation  Model input/output

4. The Radiation Belt Environment (RBE) Model Solar Wind, Dst, Kp data Radiation Belt Environment Model Energetic Electron Flux (10 keV – 6 MeV) Magnetic Field and Electric Field Models Plasmasphere Model Wave Diffusion Model Plasma Sheet Model

5. Radiation Belt Environment Model: The Equation : phase space density of electrons : magnetic latitude at the ionosphere : magnetic local time at the ionosphere M : magnetic moment K : longitudinal invariant : drift velocities (convection + magnetic drift + corotation)  b : bounce period Radial diffusion is included implicitly in the time-varying magnetic and electric fields.

6. Radiation Belt Environment Model: The Input  Dst, Kp: Kyoto University Geomagnetic Data Service  Shifted solar wind data: ACE or WIND satellite  Magnetic field model: T96 or T04 model  Electric field model: Weimer model  Plasmasphere model: Ober and Gallagher model  Diffusion coefficients: Horne’s PADIE code  Distribution at the outer boundary (10 RE): kappa distribution Nps(t) = [(0.02 Nsw(t-2hr) + 0.316)] sqrt(amu) cm^-3 Eo(t) = 0.016 Vsw(t-2hr) - 2.4 keV

7. The PADIE Code: Pitch Angle and Energy Diffusion of Ions and Electrons Electron diffusion rates for whistler mode chorus waves (wave amplitude = 100 pT) Taken from Horne et al., 2006

8. CRRES Lower-band Chorus Wave Data Provided by N. Meredith

9. Radiation Belt Environment Model: The Output RBE Output: 3-dimensional Electron Flux from 10 keV to 6 MeV at all pitch angles 800 keV electrons

10. Magnetic Storm on 23 - 27 October 2002

11. RBE Simulation of the Storm on 23 - 27 October 2002 Pre-storm

12. Early recovery RBE Simulation of the Storm on 23 - 27 October 2002 Pre-storm

13. Storm on Oct 23-27, 2002: RBE Simulations versus LANL-SOPA Data

14. Storm on Oct 23-27, 2002: RBE Simulations versus SAMPEX Data SAMPEX: electrons: 2 – 6 MeV RBE–T04 with WP interactions

15. Storm on Oct 23-27, 2002: RBE Simulations versus SAMPEX Data SAMPEX: electrons: 2 – 6 MeV RBE–T04 with WP interactionsRBE–T04 without WP interactions

16. Storm on Oct 23-27, 2002: RBE Simulations versus SAMPEX Data SAMPEX: electrons: 2 – 6 MeV RBE–T04 with WP interactionsRBE–T96 with WP interactions

17. Two-Step Acceleration of the Outer Belt No WP interactionsWith WP interactions RBE with T04 RBE with T96

18. The RBE Model Running in Real Time Real-time ACE data: Nsw, Vsw, IMF (NOAA) Real-time Dst (Kyoto U.) and Kp (NOAA) Radiation Belt Environment (RBE) Model Energetic Electron Flux (updated every 15 minutes) Real-time GOES-11 (E > 0.6 MeV) Real-time GOES-12 (E > 0.6 MeV)

19. http://mcf.gsfc.nasa.gov/RB_nowcast/

20. Summary  A data-driven physical model of the radiation belt (RBE model) has been developed to understand the radiation belt dynamics and provide prediction of the radiation belt environment.  Storm on 23-27 October 2002 was simulated. We found a two-step acceleration in the outer belt: 1. Particle injection and radial transport form a seed population 2. Further energization by interacting with waves  Storms that are not able to produce seed population or wave excitation have no radiation belt enhancement.  The RBE model is running in real-time at NASA Goddard and compared with GOES data: http://mcf.gsfc.nasa.gov/RB_nowcast