Storm-dependent Radiation Belt Dynamics Mei-Ching Fok NASA Goddard Space Flight Center, USA

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 • The Radiation Belt Environment (RBE) model • Model logic • Model formulation • Model input/output • 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

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

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

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 RBE–T04 with WP interactions SAMPEX: electrons: 2 – 6 MeV

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

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

17. Two-Step Acceleration of the Outer Belt No WP interactions With 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-12 (E > 0.6 MeV) Real-time GOES-11 (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